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Eutectic decomposition in the goldsilicon system
Eulectic Decomposilion in Ihe Gold-Silicon Syslem (3 A A N D E , , R S E N , . I
A JI.)HNS(_)N AnT) B. PI)ST
L BFS'TE,.L,A
D~'pml,w,I ol [gn,.st~u/ tt,d ~lllqlllt'l'rlllll ,~h'hdh#qr
I, slzlull' ot BI(IO~II'H
[ltlll'lt'lIh/lll'
BIOlPI~/III I%' |' I1701 t/
%'..II
(Re.t'elv~'d hllv 2,-I, 14711)
St," ,Iii ,~1,4
I..".Slllfl ~l !lira Ilr .Vc¢lr~'!lt/l/ol/ h'C/lll/qll~' /I /..I,V b~'¢'/i S]ltllt'll l]llll lilt' t'll/t4'll~' COIIlllll~'lllOll Ill I[It' !lO/dSl/ll'lOI ,gr,~/['/ll ol'l'lll,S ill 17 U ¢11 ". ~l/ll'O/I ]]']l('ll till ~l//lll' O/ /Ill' ¢'111¢'~'11~' I'lllllplt,WIl¢~ll I~ qllCllt'ht'd /i'ltlll
I1.' /Iqlltd /dld,S't' ~l Illl ~Illt'e O/ !lohl nlld ~t II.'lasl,/h/u p/lll,s'e dt',Sl!ltll/h.'d " 6 ' I,S /~.'ll.'d Thu h IIlll/St ' U'/IIHI /Ills ~1 ('~PlIIIPIII~'III~III lit'Ill
All ~,.~'l. /I(I,S IIII IIl'[]ltll']lOItl/ll¢'
R
)'
vlrIICIIII'C nll/I ;.I : 7 ,~'2 ,']', b: 4 44 .~ ~llldt.' : I I 16 ,q' ,'~1 /'lIt#l/ It'llllpt'rall/l't' tl Ih111 ,ill//fir/' hllt'l' Ill Iht' ~ ~]ltl.S'l' dI,S'i~'lll'ldlt',S' Ill ~'l iI [It'l It/(/ It/ ¢1 /f'll' ]IOIII,S', lilt/ 111~' I I'SI Ill I/H' ,S'pt'rl/llUII I ('llltllll,S IIIh/I,Y,Ylll'l~llt'd UI I'll II/I['l' ~1 pt'lllll/ O/ OII[' I'l'lll (.'lllllp/t'lt' dlS,StH'ltlllllll Ill
~l It. /lOlllS u'n.s O/~.S'UI'I~'l/ with ll/lll~lS =lt I Sll"(" ,/Ill wIHI lull/, Vu'~'/nlt'/I,S ~/I ¢411 C
R E s ( . / ,~ ~, E,)/ ulll/,,,',ll/l /IIl*' lt'C/ll/Iql/t' du ,',¢;!Ht"!lal/o// pdr !ll',lt'll(, /t%' tllll('l/IS 0111 tllOIlll ~; q/If hI (lOtll[plI,Ylllllll t'lllf'lIIIqll( ' d/IllS h' ~'l'SIt"lllt' Ol'-,sllll'llllll ('Ol'l('SPOlld ~'1 Illlt' ('lpll~'~'llllllllOII I.Illlllllqllt' dr' ,W/ll'llllll d¢' 17,1~. L, oI',s' qlt'llll tl/lld!lt' lh' ('lllllplISIIlllll f'lllt't'llqllt' t',sl llt'lll/h" dt'/llllY rl"Idl hql/idu, II .s'(' lo//lle Illl m('hm!le ,/'llr el
• /'l/lie pha.st' /ll~;la.~lohlt' ~h;,~l!lll(;~ ' p=l/ "~3"' L.a pll,/.~'~' i'i, lhml hi CO/llpO,v/lloI/ eSl ploclle =it' ,~11~1~1, U t ~ ' Slrll~'lllre Ol lhol'ho, IHql/u az e c u = 7,,4_2,~', b = 4 '~4 ,~'
cl ,: = I I, I~ ,~ ,4 hi le/llp~;/al/ll'e tllllhlallle lille Illlll~'e co//ctlc ,~'l/perllclelh' &' la plrm' iS ,st' dt;c.//Ip/I,~'e a. BOll/ d~' ql/chll/¢s Ilt'l/rt's, .lal~' hi pul'lle I~',sh//llU lit' /ll;l'hllllll//tlll l'~',~'/t' Illlll (h'~(Illl/lPl/I~'t'~( ' lIlt;lIlt' /It'llOdl' lit' I/lit' LIIlll("t' [/llt' df;lIlltllllll%'l[lIIII
a~l't"I~' HIlt'
I'Olllll/t"l~'
t',sl oh,vull'~;e all hOl/I de ql/ehl//e.s' IlUl/l~',S' dall,S d*' hi hl/lal/h' polt¢"u ,i I'~II"C el d,m,s ~h',s' ~;ch,#lll//Oll,', ./llsslls clla/i/]Ls ,i 140"C.
Z I ~11~Iiq '~I ,A! E ~ F,I S I~1LI, N G
l/Ill HIIIc t'lllt'l' S('llu'urA't/HI-Scqrcq, tllOl/,~ll/clllmh' It'l/I dr' qt':t'i~ll, ,h/l)' dlu t'l/It'~ l/,~'ct/t' Zltsallll//eltst'l:/tl/q ll~',~ ,~.'VSlelll,S Gol, t-SIh:ml/I hel 177~ AI ". I1¢!1I Nucll ,qh.s'cllrel'A('ll eiiler L,qllUrl/ll!l t'//lt'~llS('ht'l' ZllSal/IIlle/l,~el:I/II,# al/S del /ll/,~S~!lell Phase hlhh't slch ~'l/lt' /tll.~'~'ll///l!l al/S (hlht l/lid Ulller Ill¢la.~'hlblh'll PtlllS~' ( !lUllalllll "~5"') Dlu i~ Pllase hal ullle Zllsal// IIIt'lll~'~'l :llll,~ I I 011 t'[ll'¢l All IS/Illldt'lllt'lprlh/ll'hlllll~l,Y~'ll~' INTR(
)1 )1.1( '"t I( )N
(3uld and ',,lllcLm are almost totally imn|14t'll'dt' irl lhe ~(dld ,,;[ale I': They lorm a eul¢clic ut ab~l.iI ~7()"(.' and al a c~mpo.41tltm which ha4 becn variuunlv reported u.', t1(), IN6 ;ind 1'7()ul ",,
Str//~/llr
B¢I
I/It1 a = 7,,42 ,~', b = ~, ~ ~ ,.1' I/Ill/C = I I, I0 ,4
Rt.lllllllt'llipL'l'tlfllr
l/I,~,~'/IZll( 'l'f Itlllt'/hd/~
IlOt']l
lilt'hi
dl,S'SO:llUr/
I'o//s/ll/Idl!l~'
Di,s',s'o:lallOl/
u'/o'dt' all Spallell hal I ~(I" C i/lid all /~Olllpa~(te/ll i~l,II,'rIiIl he/ ¢411' t." b,,ohl/cllle/
'.,llic(m ~ ', K l e m e n t ¢1 al ~' h~l~,C r t ? ~ r l e d lhal an aun~rphou.4 material 1,4 I'~rmed when an alhw c~mt~llnlng 2 ~, al ",, .,+lllc(~n i,,., quenched Irwin1 the hqtlld slalC, and that this tratz,41'~rnl,,,, sh~wlv al r~(~un lemperuttlre illh~. LI cry,,.;talhne phase ~1 cuunplex ,~lrClt'lurc Slmlhlr ,~b4t'rvatl~m,~ wcrc made by
[Ihlli'tltJl+, ' %'t H'III'I' l/lit1 I-~llqllll'l'llll!l ,*mt'r. an N,.'wlv I . r MelJl,,
lilt'Ill(l('/
Sttllllh', elm' d/'/ll/lU Oburfl/h '/lellscllll'l// d('r i~-Pllase. dl'r Rusl der Pl'ohe ts/ I('lhl('ll Se/hS/ /laCh Ulll('lll .lll/ll'
Mel.ll,, Purk, q )Prop ,JmJ I-,I,,evwr Neqmua ,4 A
Luu,,;.nrw
Prmled m IIw Nelherhind',
N,,-I
<_; A ANDI-,RNON cl ,<31
Prede+..'kt el ,tl ~ tJ,',;ll'lgan alloy ~,,'~,+nlaliililg 2() at ".. ,',;fllC~m, und Ihey ul,so ,,,+howed lhul the c~,tlplex crw.;talhne pha,,..~' ~.'ould he ~blalned dtrecllv by u,'.+mg u m+mewhat hw+,er quenching rule Neilher <~1 Ih~*se two gr,~upn ~1 worker.,+ carried ~mt del'm=t~ve ,~lructure delermmatton+, but Predeckt t'l +.d len tal~vely c
ME,A,",;I.I R E,ME N T' l tF, 'THF E',IJ'TE,( 'TIC' I"I_)M P4 tSI T'l( tN
As a first .'+lep Iowatd'+ e,+labli.~hing the true eute~.'lic c,~rnD~.~fl,m HI was def.'Baled Io study alhw,, ~,1' lhe lhree ~.'.,~mp~,+tlt~ns pr~p,~sed b~, Ihe earlier workers
mentioned ahLwe, it, t11), IN(+ artd 1'7() ut ",, .~il,.'on Appn~prmte :lm~unt,+ ~1' gold wire and powdered ~ili~.'~n b~th o1' qqt.)qq,, purity, were +.'ulel'Lllly weighed ,~ut iiiI,) quartz luhc~. ']-he tube.,.; were eWlCUaled and mealed, and Ihen placed in a I'urnace ul II)()(I"C I'~r 24 h,~ur,,+ Finally, they were alh~wed h~ ~',~,~1.~h~wly to r,~,ml lemperulure ii1 tile ful nu t.'e ]-he mt+.'r=*.~lruclure ol each mg~,l wu'+ curel'ully e ~a m reed hy prepar t ng D ~l=,+ltedand el~.'hed '.;ecI i~m.,.; A rtllXlLire ¢+~[.'t4.]Llet~LINpCHa,',;,',;iLIm,~dlde .'.+;Oh.lli(t,tt and lib.'lure ~1 t,~dlm.' wan used u.~ an elehanl ]-'he ulhw Ihe tipper '~Llrl'a~.'~:
~, NI]IL'(Itt
Fq.+, I An c~;Jmplc ~1' Ihe *.'hie,,,1~ ,,+L'rq'~l,dru='lure h~rrned b,~ eule~IH dL=L~Pnlr~,,,=l=,~nm a p~dd ,,d, ~n alh~y ( . 2(1(I) /Ihn+,l
5,1 L.+I , ,l(iqll)g'~_~l)
El I'TE,I_'TI( ' DF( 'l )MPI ),.%1Tl( IN IN (J( IL,I )-NIL II 'l_lN NY,N1F,,M These lentlil,~ wele inlelpreled hi mean thai the alhwn c~mlaulinl? tl () and IX6 al ",, sillclln were hvpereuleetle alh,ys, while the alhly L',lntalnulg, 17() ;.it ",, slllclm was hyp,)eutecllC Thus. lhe nlhc~m h.Jnd ~m Ihe uppel nurlacen Ill' each Ill' Ihe Iwo hyperel.lleelle alhws wan relecled Irlml the INuid phase, and II(lated hi the nurlaee, as each alloy was c~._)led hlwards lhe euleclw lemperalure Smnlally, i?,~)ld wa~,~ rejecled by Ihe h~pl)euleelic alhw and HI lended I~, ~,?,ravilale hlwardn Ihe bl)llt)m ~ll Ihe specimen t'tll~ inlerprelalHm implied Ihal ltle lille euleL'llL' ~.'llnlp~)sllllln was II~ be h)Lllld s~llllewilere helweell
171) alld IN e, LII ",, .~lllcon AI,~), II Inlphed lhal Ihe chlne.~e ~wrlpl ~lruclLire I'(lund III all Ihlee .~peclmem~ shlluld have Ihe ellleCllC ci,inpli.Mlion Malerlal Iree Irllm ellher slllom parllcles~ir I?,(dd dendrlle~ was lhereh,re laken h . wet chenllcal analy~,an I'r~ill~ the ,,,ec(md alld Ihlrd speellnens Tile analyse,~, which were calrled ~)tll al the Bridt?,ep~irl Te.~llnL.~, Lab,,,, Brld~,epl)ll, (_'~mn revealed ll'lal bl)lh nanlples cl~ill:lilled 17q ;.it ",, nillom T'hn.~ Iheil iN Ihe llue L'(IFIIpll',lIl()ll Ill' tile L.,idd slllelln euh.%'IIC T'~l check Ihin result a specimen cl)mallllll~ Ihi,~ ;inliH.illl ill' ,SlIIL'(H1 wan prep;.lled tl,Sllll#, leL'hlllL1Lle~, Mmtlar Io lhll,se de,scrtbed ah(ive I1'~ ,slruelute clmsmled s~,lt'lv i)l'ehlnene ,~crlpl wlli~ m) evidence whal,,i,ever o1' relecled slllc~m ~)r L.,idd
~"~
aln~ healed h) I()()()"C and e~,fled hi ~()(Y'C In lhe lurnaee, bul was Ihen quenehed inhl iced waier When Ihe euleclle alhws were examined melalln graphically II wan I'uund Ihal Ihe lhree o,fllnL~ rules had pruduced ihree readily dmtlngul,shable nl~)r ph~flot~le,s 'The Firm e~hlblled, a,s e~pecled, Ihe chinese nerlpl slruclure The ,~ec(.id exhlhlled solne chinese scrlpl ,~lruclure, ailh~)ugh ~lrl a rmer ,~cale, but al,~ eonlained area,~ ,~1 an apparenlly lamellar slruclule The Ihtrd c, mlamed what appeared hi he a i,,J hke slruclure, the rl)ds having dmlnelern ill Ihe order ~ll ()'~ I~ II is ,fl' e¢ltirre dangerllLi,~ Io alleirlpl h) deduce ltueedilnensl~mal .~lluclLires I'rl)lll lwll dlinell,~l~lllal lnlcro,?,raph,s, and s~) Ihe,se de,~erlptllmS .~h~,JId he re~arded an lelllallVe The Ihree h~pl)euleclic all(w!, wele Iound h) have .Mmilar slrtidtires excepl lh;ll primary g,~fld derldrlles were ,lh.~erved Ill ti~e lW~l lhal wele m)l quenched The IWu qtlellched alMy,s were sllvel irl coh)r inllnedlalely al'ler quenehln~,, hl.iI Iurned glfld ~)ver a period ,,l'~everal h, lur,~ The alhw,s Ihal were rrl, tre sh)wly c(l~ded were always ~()ld in ~.'lll(,r KniIill~ lillCr(lilardlle:~s mea~,tlrelnelllS were carl led ~)tll lilt each i~l Ihe eule,:lic alhw speeimem. The mean values i)l~lalile(J hlr Ihe i)r.~l, se,.'nnd and Ihird specllnen,, wele NNg I t l and 2h I-)
'n-lE' SI-RI_IC'T'IIRF' ANll ('I)MP(ISI'T'IIIN (_tf THE' ~'~ PHASE'
M()RPHIILI_I(51FSllE, A FI_ITECTI(' AND A HYP(I[I.ITE'("TI( At L(_IY
The nexl phase ~ll II~e inveslll?,all~m was aimed al i)hlallllll~2. ~)ne ,ir nil)re ill' tile el~lnplex ery.~lalllne pha,w.~ rep~rled m lel'!~ h-N a.~ being h)rmed nn cluenchin.p, hquld 1..,.~fld-Mhclm alhwn Fllr lhm purp.,se Ihree specimens o1' tile el.il¢cllc alloy (1'7 i) at ",, nllnc~m) and tiuee .~peclnlelm ol'a ilypl)etileCllC alhw (I '7 () at ".. Slile~m) were prepared These were L:,r,luped mh) Ihree I'~a.:~ ~)1' speem~ens each p a . eIUINlSlii112, Ill' ()lie el.lleL'll~.' and ~ne hyp~)eLlleellC speciinell The hypl)eulecllc .~pe¢llrlell~ were In eluded :,o as Ill e,(ph)re Ihe po.~nlhilil~ lhal exce~s L.,,idd telected I'r~.~l the liquid pha,se ml~.,hl prlwlde .iwlealmL.,, sfle,,, I'(. one ~)r .)lher i~l' the phase,~ in the eLlleellL' iniXltlre Iherehy ehanplnb~, the mllrph~d~)L~,y ill Ihe rnl~lLire The lirsl pair wa;, healed Io I()()(~'(.' and Ihen alh)wed I()Cil,II II1 tile furnace, lU.~l a.~ Ill lhe previous e~perllllelll,S Tile Neelmd pall was healed to I()()1)"(_', el.ded In Ihe lurnace hl '~(M)' (.', and Ihen all~)wed hl air ~'l~,,I hi r~)ulrl lenlperalure TIle lillrd pair wa,~
The nllver L'~,l~r ,~1 Ihe qklenched alhw.~, and Ihelr d,.'veh~pmenl ol'a ~).~fld ,.'~l~r ,,n .~landm[z at r4,,n leml~eraltlre, ,suL.,,izesled stnmL:lv Ihal their slruclure wa,, i~llwr than a etllectle intxlure (ll j?l)ld and slltc,ln Behaw~.Jr ill ttus lype had heen rep~)rled by Iwl) earlier gr~lul.v~ ill'wllrker:, '"~, whll :dl(iwed that Ille ~.'l)l(ir ehLinl).e IS due h)lhe dl.~NOClalilm Inl()[.'4 fld aild ,,dtclm i)l a sull'aL'e laver ill i,ne 4,1' lhe c,,nplex ~.'l V,slalhne pha,ce,~ I'llrmed un quenching Furlher evidence piHnlltll. ~ in lhu ,salne dlr¢Clllm ~a:, ~lhlamed I r(.n a ira,re carel'ul ,~ludy ifl Ihe ;,IruL'll.lres i)l Ihe quenched ~peL'llllel'l~.; tllldel Ihe iIpltcal mwrll,,e~)pe F'ms[, ii wa!~ hi)treed Ihal Ihe vldume Iracl,_m ~ll Ihe hL:hl rl)d hke slruelure~< aSSUlrled hl he g, fld, was much :¢lnaller than Ihe vlflume Ir;.ICtl~lll ~ll' l:-'.,Id Ill the chlne.w .~erlpl ~lruelures Secondly the l|ialrlX pil;.i.~e clearly did lll)l C(HISlNt i)I sill¢lm becauNe II had h)ll ,Nlrlm~.?, ;.I mela]lic iLislre I1 waslherel'l~relenlaliveiycllncluded Ihul the Mructure i)l Ihe quenched speclrl|ell.~ c~in sl.~led i,I ~,~dd rl)d:~ embedded in a inalrlx (ll ~,,Olile iflhel pha.~e C~lillaillili.p. blllh gl)l~:l ;.ind MliCIHi T'his ,~lnh'p ,%'~1£5.1 ,7(I,~7J)Nt_,~()
g~'l
(_; A A N D E R S O N
malrlX wag designated Ihe ",) phase" bearing in nuncl that Its d e s l g n a l l O l l might have h~ be c h a n g , e d II II lurned ~ut h~ he idenllcal with ~me of lhe phases already rep~rled m Ihe hteralure. Nexl. the crystal slructure ~1 Ihe ,) phase was studied usingX ravdiffraclum teehmques r)ebyeScherrel D~wder pallerns were obtained I'r~m rdlngs using copper K,~ radla lion and a n,ckel Idler (F'lg 2) S~m,e ol Ihe rnany hnex on these patterrix L'~Lild readily be idenldled as due h~ pure g~ld The re mamder, due to Ihe ,'~ phase, could mfl readdv be indexed. T'(~ oblalrl precise values ~11 211 I'm each r'elleclum, dlllracl~meter Irucex were ~blalned using speeunenn p r e p a r e d by gluing I'~hiu,,x to a glass slide 'The besl dll'l'racll~m palterus were ~blulned after anneahng Ihe I'lhngs h~r I hour at I()()'C 1o rein(we 41rains 'T'his Irealmerit sharpened each peak but did n~H change the nalure ~1' the palter,, In indexing Ihe hries due h~ the 0 phase (Table I) il wax h~und Ihal many o1' lhe sh_ml:,.er ones c(~uld be aco)unted I{~r (m the b;.lSlS ol a prnlrullve cLlbnc .',,Lib cell wilhd = "~q()A The remainder aree~mslslent with an orlhmh~mblccell wdha ='7 g2 A.h = 5 '~'~A and c=11.16 ~ These wilues ca,, he expressed ahn~st exactly as o = 2 , lql) A, h= x,,"2 , tq(I ,,~ and c= v"g , t qt) A 'Thus tile ~rlhorh{~mbic cell Ix ba~ed ~n the p r i m i t i v e Ctlbl~.' sub cell and has e,ghl times its wflume T'he mde.xmg m 'Table I has been carr=ed (u.=l uMng mulu,'=llv ~rtho.g~mal axes wlHch are parallel to the [ I()0], [I II)] and [22()] direclums ~1 Ihe cubw stihcell 'The lalllce par,'lmetel ~l'lhe cubw sub cell is very s,mlar I~ th.'lt ror pure g~dd (40'78h ~,) A unit cell (~1 pure g(fld c, mlams I',mr ahmls of gold, and Ihus II seems reas~mable h) assume Ihal the CLIblC s u b cell c~mlams ~me unil ~1 Au~Si, ~.e. three ah~rns ~l'gold and one ~1 slheon II lies is s~ lhe tinll orth~rh~mblc cell e~mlams elghl Au ~SI umlx. The appn~xunale c(,mp~sltlon (.ff tile t~ phase was delermlued using a quantllalive melalh~graphlc technique An enlargement ( , .S000)~fl'a mlcmgraph uf orie ~d' Ihe quenched eutectlc alloy specHnens sh~wing a leg,i,m where Ihe gold r~dx were normal h~ the xurlaee was prepared (F'lg t) The enlire
~'I ~.ll
TABLE' I INDEX, IN(, I)F LIIE'FRAI'[IIIN LINEN DIJE II) THE ~ F'HAN[ IN A 1211ENI'HE,Li L,IILLI-SILI('4)N FIITEi 'II1' ALLIh'
2fl
I.t,'.~t I'
,1~,;i
,I,~,,~,
(hi, I)
2 / N' ~2,-lh'
V ~ea k Medium V v weak V weak V weak Weak SIr~mp, Medium V ~ Weill~
It ()6h ()I~I
i) l)te~ I) IR)
(2IX)) ((12(i)
(114 ~
1) J,4,4
(11),4)
()1'~'~ (llhl (I I 7t~ (I Ig7 (I 2hi () 2N'~
()IS"~ ()lhl O 177 (I Iq~ 0 2hi l) 2N'~
(;()1) (OI4) (I 14) (22(ii
V v weak
O H)N
l) tl)q
(,4tlO) ( ; 21 ) (t22)
'~2 1" '~'~ N
V we,Jk V v weak
() ~2t~'~
l) lr, N
(I }07 t) ~2t, (I 1,~~t,
(~1,4) (,412) {2 ;I)
'~6 7
V v WC,lk
I) lgl)
(] tgll
(11'~)
'~7 7'
V v wL'ak V v weak
II ;q? Ildll)
(i t'41 (I,4()N
(,421)) (Ill/)
V v weak
(I d ~N ( 14 "*,-I
{I ~h) (,4 ~,(i)
;,4 (~"
;S ;" ;t~(l" ~7 7" ,40 0" ,4h ,4"
,IN (; '~1) 7'
'~q 2' hi ()'
t, '~ 8" ,,t~ 8"
V weak
l) ,4 ~,,4 I ) ,4 '~,.I () '4 7h ~) ,4'-)1'1
V ~wak
hTq"
V Wedk
(-;=1tl' {,.I 2"
'~t ¢d l ll m
V ~,¢al'.
(i ,-I 77
(~,~h)
(I ,4q,4
(,41 'q
() '~10
0 '~(Iq () '~12
(IX)H) (I ;",)
()%2%
()'~2
(l),.lll)
micr~graph was weighed, and then the areas representing tile r~ds were c:irefully cut out with u pair ol'sclssors The remainder ol the mlcr~)g,raph, i e. the part lelt alter the areas representing lhe rudx had been rem~wed, was weighed again. From the resullx o1' these weighmgx the v~flume Iractmn c',f rod,; wax calculaled a,ssummg that the fracture q~l the mu.'ro graph representing rods wax equal to th=x w~lume I'racl I~ln 'T'hen, I r~,n I tl=s W~ILIme I'rac tu m I he corn po silum ~1' lhe a phase matrix wan calculaled The result L~blamed w:lx that the ,'~ phase c~mlainx 2,-I 9 a[
". stiletto
It is dllflcull h~ esllmale the accuracy ol Ihis melh(~d ~1' determlmng Ihe composition of the 0 phase If the mlcrogruph lruly represenlsan array of gold r~ds, exaclly nurmal to Ihe sLirlace, in a mulrlx ,~1' the ,'~ phase. Ihe aXSLimpll~m made in w(~rklng IH.II the wflume Irat'llOn or D~ld m exactly rig.hi II'the conclusum that Ihe slruclure c~msmls if,l, I'iL ,'
'll, 'l[p' '% I,!,~1 ' J"Ip ~ A D e b y e
.~;Lherre[ X r=Jv dillr,Jciion p.'ilh.=rli ,~hl.iln~.=d w i l h
J q u e n L h e d h q u l d gold
ii
,,lh~.on a l l o y ,~I lh¢ I.'LII¢¢ IlL ~.oml.~O';llliHi
,'llah'l .~'l i E).I , 7 (liT71) 8 1,-~-~(I
El_ TE'('TlU I)t( qiMF'(U,',,ITII)N IN U.,()LD SILI('UiN NY~TI-.M
N7
Fnl~ I The rrn~rq~,.,IrlUi.'ll.lr9~,I a quen~ht'd f'~dd !,iln~~,rl i'lUh~li~ Jll,~y ( . '~OAX)) ~1' r~ds happens I~ he wr(~n~, and, liar example, we were aclllally ~,b,~ervin~,, secltc, n'~ ~1' spheres. Ihe as.sttmplt~n m ~ltll quite .p,~d and pr~bahly led t~ n(~ rn~re lhan a lew per c'e111 err,)r We d() nOll h~)wever, Ihtnk LhaL tt us very hkely ihaL the micro f~raphs have been im.'~rrectly inlerpreied Atl~lher p~ssthle source o1' err(~r was varuattun tn the Ihtck ile~,s ~r derlsily ol Ihe ph~h~l?.raphlc paper used in preparmL.'. Ihe rnlcro~.raph, but again tl ,~eems un likely Ihal Ihmexceeded a I'ew per cent Finally, Ihere may have heen s~me error irl c ulltn)..,. ~ttl Ihe requited parl,~ ~1' Ihe micro.graph since Ihere wa.~ some blurring ~1 lhe r,~d-malrtx tnterl'a~.'es because Ihe ~ptic'ai unler(~e(~pe wa"., heiru?, used near sis iumll ~1 re,~dulu~m ( )verall we reel thai i1 t~ unhkely thai an err~r ~1' m~re Ihan ± I()",, wan rnade m delermmnnl?. Ihe ,~ilicon e~mtent ~1' Ihe ,) phase T'hus we estlmale Ihal Ihe '..;iIi~.'~HI¢~lltenl i,~ m the ranlg.e ~1 2'~ ± 2 '~ al ",, Thin appr'~rxnmale determnnaln~m ~,1' the ,'1 phase c~rnp~;,ttton Iherel'~re leads u.~ h_~ lhe con clttsi~rl thai it i.s based ~m the h~rmula All ~Si
DF,I"(.)MI"(_),.%11ION (.IF 'T'H[' ~:') F'HASF T~ ~ttudv the dec~mp~stli~m ~1 Ihe ,) phase al elevaled lemperalures fihngs were prepared I'r,,n a quenched euleclle alhw specimen Irwin1 which the
Iransl',~lmed ,~urlace laver had been remm, ed 'The I'dlnL~,,+ were annealed at I~,(.)"(Y and at intervals they were c'ouled It+ r ~ m temperature tt~ lake Debye-Seher rer pa tier n.~ SLIL'~.'e.SNIVe palter ns .~h~~w ed weaker and weaker ,'~ pha,~e Itne,~ until, after '~ h ~ u r s a t I ~ ( ) " C , ~ n l y Ihe Itnes~.'~rtesp~ndlng Io pure .p~dd were ~bserved II m assumed Ihal re Ileclt~ms I'r~m lhe sdlcrm, wtHL'h must have been presenl, were ahs~rhed by Ihe guld F'urlher expermlenls using an anrleal,nL:, lemperalure ~1' IIX)"C ,d-i,~wed Iha[ at [hl'~ lemperature Ihe dts.s~¢ta It~n wan .~ldl mc~vnplete after "~ h~ur~ AI 2()1~ L' c(nrlplele dissoelall~m ~,.'~.'urred m nh~,ul 21) rrlmtiles T'~ stLidy Ihe dlss()ctalhm ~1' Ihe ,'~ phase in hulk .'~peetrnens. a number ~d' bulk narnple,~ were annealed al ~.-II)"(J h~r perl~ds ~ffup h~ ~ h~urs E'ach ~ne was examined melalhLp.raphlcally, and Ihen mtcr~ hardness measuremenln were carried oul ~ll it and I'tlln~.s laken Ir,,n it were u~ed h~ ~htaln a DebyeScherrer pullers T'he nletalh~.raphl~.' resullnsh~wed lhe hleakd~wn ~1' the quenched :druciLure inh~ irregular needles ~)r plalelels ul' stll~.'~m in a g.~ld irlalrlx (wet a periled ~1' ah~tll 2 ~ h~l.lrs (FIp ,4). Alter ~ h~tir.~ Ihe ;~,lll,..'~r'lnl~rph~h~gy had ehan~ed to irrel::.ular ~.lnbules ~1 Ihe order ~1' ~ lU m dtameler The K n o n p hardness lell Ir~m a value ol 2t~ In a value ~1 '7~ .'~l'ler 2 '~ h~urs, and Ihen decreased sh~wly I~ f,N aller '-) h~ur'~ The Dehye-Seherrer pallerns ,~l.lur
~_',t tt.i
'(l'~71)N; ~()
NN
G A AN[IE,RSIIN t'l ~//,
F"~I:, 4 The ITIICrOMrul.'lure ol ,.I quen~.'hedp,l~ld-.s=l~.',~nelJl¢CllC allm, aller ii had heen annealed al '~,-I0"C Ior 2 ", hour,,.,Io c,.iu,,edu,,~,oc=a lion ,tl li~e ,~ pl~u:ie ( . klili)
,d]owed Ihat the dnss(~cnatnon was complete ai'ler 2.", h~lu r,,, A quenched specnmen wa,s set .'mnde in the labora tory I'~,r ~ne year so as Io study the ro~m~ lemperature slahility~llhephase Ilwa,sl'(~undatlheend,fl'lhis period thai the dissociation was .,,;till restricted h~ a Ihm surl'aeelayer Thus il seemslhal the,~ phasei,s slable al r~.~m lemperulure even iwer a long p e r ~ d ol lime
E)lgCl.l,ggl( iN
II ~,~ w~rth c~ms~dermg why Ihe pubhshed value.``; ~fl' the eule,:tp.." ,.~(.~,ml.~,~'.;~l~,n'~ " ,~h~,w such a large spread ~,I' values, alid whether lhere are .,.;(,urid rea..s,~ns lur heliewn~ lhal lliese puhl,,.;lied value.``; are nnc~rrecl and Ihe une derived from lhe presenl wllrk c,',rrecl 'T'he work ol E)~ Capua ~. wh,ch led I~ a value ol tl l) at ",, silicon, was carried ~ul nearly hall a cenlLtry ag~ using ,silicon c~nlatntng ah~lul ~,",,~*ltrnpurtltes I t c a n t h e r e l ' o r e b e r e l e c l e d ~ t l l h e gn~,unds lhal the trrlpur~lws substantially trilluer,.'ed hm re.,,;Lill T'lie value ~I' IN h at ",, ,~dlc~m pr~,D.~sed by Heath "~and llie value~,117 ()al ",,,,.,dp,.'~m pr(',p~'.; ed by Gerlaeh and (]~el" bolh he wHhm less Ihan I at % sdic~m ~ll'the value ~1' 1'7~ at ",, sdp.'~m derived Irom Ihe pre~enl w,~rk 1-'he degree o1'
dmagreemenl belween Lhe Ihr'ee resulls is iherel'~re nol very greal Healh eqmhbraled an alloy near the euleclJC c~mip(,,rlll~m at 3N()"C, l e aboul I()"C ah~we the euteclie lemperalure, and then quenched iI into cool od A chemical analysl,s, carried (lul by an un,specil'led technique, was Ihen carried OLll on lhe I'rozen liquid. There m an mherenl error m Ibis technique ,~ince Ihe liquid in equdlbrlunl with excess L.,,~dd or silie~n II)"C above [lie eulectlc tern peralure in n~l prec.sely of the eulecl ic c~mpo,ml~n I1 i,s lherel'ore coilceivahle lhal I'~r Ihis rea,,.;~l'l Healh's result cl~uld be m error by as much us I al " . ,',;IhL'on Oerlach and (Joel used Iw(~ melh~ds Io determine lhe eulecti¢ L'omD)MIl(m. First, Ihey carried ~)ul c~,~linL.~, curves and ~blamed p(vnls on Ihe liquldus curve I'~)r ,~everal alhws SecLmdl.y, lhey u,~ed a penelrall~m lechmque which gave pq~inl.s cm the hquidus curve on [he ,~ilic~m rich side o1' Ihe euleclic comDl,~H..m Thin lechnlque Hivolved placing a thin layer ol'guld ol kn~wn Ih~cknes,~ un a slab ~1 s.hci~n and e q u i h b l a l l n g at .some [einperalure above lhe el.lleCllC lemperature The g~dd reacted wHh lhe sdic~m t(~ I'~m~ a hqtud phase which, being ~n equ.hbrium wilh .s~fl~d ,stilton. had a c(imp(~sili~n delermined by Ihe D~sili~m ol Ihe hquidus curve ~n [he ,~lhc(m rich s,de ol' Ihe euleCllL' comr)~slll(m at ,ll,lh'P ,%1 FInl , 1ll971)S~-~)0
F.I.IfE("TIC IrE( ( IMP( ).HIIll IN IN (J( |L D-.~I L I( '( )N SY~TE'M Ihut temperature. (_)n c ~ l l n ~ , sllle~m was redepos fled on the slah Lintel Ihe eulecltc ~.'~rrlp~l,.;ll,l~ln was reached, bul subsequenl melalh~.p.raphlc ~lbserva l,_ms enabled Ihe arnounl ~1 s i l i o m m soluti~m al the e q u i l i h r a l m g temperature hi be determined 'T'hts was p~.ss=ble because lhc mlerlare at which the slho~n b¢~.an I~ be redep,),,,,iled C~LiId be dlscer'tled n~etallog, raphwally T'hus Ih¢ c~lmp~.,.,,llon ~d' the liquid phase m equiltbr'tum wflh s~fltd sdw~m at the equdtbrali~m lemperuture, +~, Ihe i+'~silt~m ~ll the liqui,Jus curve at Ihal temperalure, c~uld be ca h.'ulated The restllts obtained by these Iw~ meth~ds agreed qtule well, and (Jerlach and (.]~el were lherel'~lre able Io extrap~dale the l,w~ branches ~fl'lhe hqutdus ,..'LlrVe .'.a~ Ihal Ihev intersecled at Ihe eulecllC c~m|p~Sltlor! 'The exlrap~dalrons e.~tended over aboul .~ al ",, s,llc(m ~m the ~2iI)hJ rich side ~1' the euleelic e(H'np()s,l,lOrl and ub,)ul 4 al ",, sillctm ~,HI Ihe s f l i o m r,.'h side 'The~, eslimaled Ihal flus pr,~cedl.ire led h~ u pr~bable error ,fl' ab,~til +_() ~, ;~t ",. ;,fl,.',m m their delermmaltem ¢~1'Ihe euleL'liL' c()mp()Sl[l()n 'T'hls C(HIClLISI¢)II ,S, h¢)wever. ,~l')en h~ ,iblection ,m Iw,~ gr~unds Ftrsl. their hqutdus line ,m Ihe sd,.'~m rwh side ~1' the euiecllC d(~es ii~H appear h~ be Ihe besl line I hr=~u[.~.h Iheir experHt~enlal p~mlls T'he best line w~,Jld brant:? the eul,eclic comp,~silion shghlly lurlher over h~ Ihe silir, m rich s,:le ~1' the dtaL.,ram 'The hqutdus curve ~m Ihe t.-'.~dd rich side ,~l' Ihe el.lleCllC IS steep and s¢l the exlla p()lall(Ul (wer a ranL.,,e ()I'2 al ",, slllc~m Is tlneel lain ;it,d (.';In be adjusted s~ thai II sllll inl,ersecls the ~qher branch ~1' Ihe Iiquldus curve al Ihe eutecllc lemper~lure Seomdlv. b~flh Iypes ~1' measuremel~l.~ may have inwdved syslenlal,c eri(~rs (_'~(dlntJ curves are subl¢cl hi error because ~1 Ihe p~s.,.;ibllll v ~1 omslllUll~ulal Linderc~dlnL~ The penelrall~m technique used may have been in err~r becatlse () ~",, ;Jllllnl~t,rlv was added to the L,~ld h~r reas, ms thai were n,~l adequately explained The facl thai the l w~ sels~d',neasu remen Is i?.ave results w h Ich agree well with each ~lher d~es or CC~Llrse Sllg.L.~esl Ihal bolh are c~lrecl, hul Ihere lemalns the p~)sslbllllV Ihal this a~reemenl IS I~)rltllh)L,S and IS merely the restlll ~ll c~unparable err~lrs ,ll b~qh sels o1' measure menls ()verall, Ihereh~re, Ihere seem ht he ,,Lifl'tctenl /2r~tlllds for Ih,nkm.~ thai (Jerlach and (_~el's rent.ill mav be Ill err~r by as much ;.,.,, I ,.11 ",, siIIc,~t,rl In Ihe ;,ulh~rs' w,~rk the fact that exaclly Ihe same value h~r the euleL'llC ~.'~)lIIp~Slll~)n was ~)blatned usn|~ l~.raVllV seL2.reL.~.all~mlechnlques Oil allow, ,m b,~lh ,,ide~.; ~fl' Ihe eulecllC c~mlp~,~ll,l~m i,~ slr~m!?
~c)
evidence lhal lh,s value is Ihe c~rrect ~me Wel chemwal analVst,s Is adequule Ior delermining the comp~nlli~n h~ l,he nearesl, I) l al ",, slhc~m, and the analvllcal lahoruh~rv which carried ()LI[ lhe arlalvses has worked with l,h¢ aLilh~lrs iwer a periled ~fl' .several years and been I'otirld h~ be reliable It IhereMre seems reasonable I.~) c~melude Ihal Ihe wllue~d'l'7 ~al ",,silirorl I'~lr theeuleL'tncL'omp~sitiqm ~>blalned m Ihe present inveslll.,,all~m in Ihe o~rrecl ~me, and thai Ihis is Ihe I'lrs[ lime thai a precise measurernenl ~1' HI has been repe, rled Indeed Ihe fact Ihal gravely se[~,regalion w~rks ,.;~l well in the L,.idd-stl,c~m syslem has enabled the ei.ileclic c~lm p~sitt~m h~ be established wtl,h an acrtirary which tl, in diMeull t~ achieve m ~l,her ,~yslems 'T'urnlng. rlow Io a dlscU,,,,Sl~m ~1' the ,'~ phase, it in pelllnenl to enquire how the resulls ~1' l,he presenl w~rk can be reconcded wdh Ihe w~rk ~m quenched g~dd-sdtcon alhws !h~ be fllund ,n the hl,eral,ure F'lrsl. since ii ,seems lhal n~ ~l,her w~lrker's have re p~rled the exlslence ~1 an ~rthorh~mbtc phase. II ',;een,s appr~prlale h~ retain Ihe des,l.mall~m ,) s(~ as h~ cllstm~,u ish Jl from all ~l'the ~lher phases rep~rled Set, redly, we InUsl dISeLISS why we have found such s l m n g evtdence h~r l i a r phase whde everwme else has lep~rled phases having rn~re c~mlplex cryslal slruclures ()ne p~sslblllly which has been sllessed by Dtiwez ~" and ~thers is Ihal the phase Iorm~:d ~m quenchln[~, a liquid alhw depends SellSll,velv on the quenching rule V a r i a l , m n m quienchir~g rule I'r~m ~ne laborah~rV hi am~ther Ihen lead h~ apparently e~mlllclJnL.., results. If Ihis p~inl ¢~1 view ts aceepled there Is r'i~, connlct between the varl~lus sets ~ll' resulls Ill the lllerature and ours Am~lher p~sslbllllv is thai, because we, rkers other Ihan ~urselves ~werlo~ked the fact thai a quenched alhw carl c~mlaln Iwt) phases, they tried h~ index Ihe lines Ir~rtl b~lh phases as ~me slru¢lure 'The I'acl thai Anarlthararr|an cl ~1 ~ rep,~rled thai alhws c~mlamlng up h~ 2'~ at. ",, s,hc,nn i?.ave ~me struclLue ~ll quenching.,, and alhlys conl;i,nlnL2 , m, tre than 2'~ al ",, ,.,llnc,~ll an, Hher slr~mgly suL..,,t.,eslsthai Ihns in Ihe ease A nalural explanult~m of ItHs us Ihal m alhwsc~nlannnngless Ihan 2~ at ",,snlnc~m they were allemplmg, h~ nndex a pattern I'rorn a rnJxlure ~1' I..~.~dd and A LUuqn, w h nle in a lh Ws can la nnnnl?.rm ~re Iha n 2", al ",, stli~.'~rl Ihetr patterns were pr~duced by a IlllXlure ~1' snlnc~ll and ALn ~Sn I.IHl'~rlLunalely their w~rk was n~H rel',~lted in SLIIl'iele,ll delafl h~ enable Ihls hyl_~olhesls lh~ be checked T'he I'lnal p~ml Io be oms~dered is whelher Ihe ,'~ I
M,m'p .%_',1E,,I
"(Iq71)X ~, ~'~q)
(.; A ANL)E, RNI_)N ('I ill
c)()
pha,.;e is [herm~dynam.:allv stable near ro~)m temperalure or melastable Pr~.fl' ~1 stabdHv w~uld have h~ come Jrom the observalion that at s~.ne lemperalure gold and slllc~n wnll reacl, however sh~wlv, h~ form thei~ phase T'hee~mtmg evidence ~n Ihe dlss~cialion of lh¢ ~ phase suggesls lhal II IS melaslable, and it lherel'~re seems wine l,~ assume melaslabilnlv unltl evidence Io Ihe conlrarv m presented.
(_)ther phases .n quenched g~ld-stlic~n alhws have been reD~rled m Ihe hlerature T'hts may be because the phase or phases fi*und depend on Ihe quenching rale, wh..'h varies Ir~m ~me mvesltgal.m t~ an~ther Another D*ssnhllltv is thai earlner w~rkers attempled h~ index D~wder patlerns I'r~m] mlxlures ~I' g,~Id and theh phase, and sdi~.'~m and lhe ,'~ phase as single phases 'Tile ,'~ phase appears t~ be metastable at and near r~om temperature but this is n(fl Vet quite certain
C'( )N( 'L.I.!,~II_)N ACK N( )W L,E'L)(jE, M F, N T'S
It has been shuwn thai when a hvpereutecl..' goldsfllcon alhw is c~.fled slowly Ihrou.~h lhe euleet..' temperalure, s~ltd sdnom us releeled from Ihe hqmd phase and Ih~ats I~ the specimen sull'ace beli~re the eulecl.: ireezes Similarly, gold .s relecled I'r~.rl a hvpoeulecllc alloy and lends Io I:,ravllale 1o the b~ltom ~1' the specmlen Wet chemical analyses carried ~ul ~n eulecllc mixtures ~htalned Irom b~,th hvpereuleclle and ]lvpoeuteclle alloys using this gravnty segrat.m technnque gave a value h~r Ihe euleelnc compt~s,l.m ~1 1'7 9 al ",, sd..'~m This value m beheved h~ be the rnost accurate so far ~,btamed I'~r Ihis system and us correct h~ the nearest ()1 at
" . NIIIc()II
When a liquid eutect..' alloy us quem.'hed tnt~ iced water a mlxlure ol'g~dd and a new please whteh has been destg, naled "i~" ~s formed T'hm new phase us ~rlh~rh~m~b..' wllh ,~='7N2 ~. h=",.",'~ A and c = I I 16 A. and has a c o m p o s n t . m close I,~ ALl ~SI A Ihm surface layer ol the o phase dms~enales tntt~ gold and sdnom ~ver a per.~d ~l'a few h~urs after quenchmg hi' Ihe specimen is lell at r~.~m temper alure N~ further diss~t,etaltorl at r ~ r n temperature was h~und even after a specnnen had been sh~red for a year E)lss~ctal..m d~es take place al higher lemperalure, h~wever, anti, I'~r example, m complele aller aboul ~, houns al I'~t)"C
'T'hts wurk is taken largely from a IhesmnUsubm/[led by one t)l' LIS ( ( . J A A ) In parlml I'ull'dlment ~1' the requnremenls Ii~r the degree ~1 Bacheh~r ~1' Science m Melalltubucal F'ngmeermg al the Polylechntc I n s t l l u l e ~ l ' B r o ~ k l v n F'tnanctalsuppor[ I'~r tl was provided Ir~.n Denial Melallurgv 'T'rammg (3ranl No r)F,, ()I)IN~ awarded by Ihe Nallona] Insiflule I't~r Denial Researeh
R E FE R E NC'E,N I E R I r t l t ,~NL~ E B GEBERF .I ~ ht'tll f'/ll '~, , I (1~1,1) 7~t (' [4 (-'qlLLIN'~, R () (.'ARIN(IN AND(' I (IALLA(JH[I,I Phr~
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(3[HI Aq H AND B CiqlEL, ._~tt/td ,~.'ftltt' E/t'tltttll
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tt ~¢V KI [ M r N I r H WILLE% ~, &Nrb [t DL%'EZ, J'~'tlffll~' I ~ (1~4hO) ~t,q 7 P le'rEl_tEq'l~,l, B (" (JIF,'~;I[,N AI'~D N I (_IRANI, rr~JtL~ AIME,, .'If (l~.)tp'~) 141~
T R ANanHnaram~n H L Lu~ and W KLtmrnt, ,,'V.lm~' ?10 (l~hh) II),.11) ~ H S (['IIFN,'~,NL~D TI'RNBIILL ,I ,4ppl f'bl',~, 1,~t(1'~67)lt,dh I1) [~)L f)I'WFZ [tiJtl~, ,'~tH ,~-I~l /lluhll',, 01) (Iqh7) hi)7 II ('; A t~N/tEI.I'sEN, B ,5 f'l.'sts f'~.lvlechn.. In,,,lllule ol
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A JI.)HNS(_)N AnT) B. PI)ST
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(Re.t'elv~'d hllv 2,-I, 14711)
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I1.' /Iqlltd /dld,S't' ~l Illl ~Illt'e O/ !lohl nlld ~t II.'lasl,/h/u p/lll,s'e dt',Sl!ltll/h.'d " 6 ' I,S /~.'ll.'d Thu h IIlll/St ' U'/IIHI /Ills ~1 ('~PlIIIPIII~'III~III lit'Ill
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• /'l/lie pha.st' /ll~;la.~lohlt' ~h;,~l!lll(;~ ' p=l/ "~3"' L.a pll,/.~'~' i'i, lhml hi CO/llpO,v/lloI/ eSl ploclle =it' ,~11~1~1, U t ~ ' Slrll~'lllre Ol lhol'ho, IHql/u az e c u = 7,,4_2,~', b = 4 '~4 ,~'
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a~l't"I~' HIlt'
I'Olllll/t"l~'
t',sl oh,vull'~;e all hOl/I de ql/ehl//e.s' IlUl/l~',S' dall,S d*' hi hl/lal/h' polt¢"u ,i I'~II"C el d,m,s ~h',s' ~;ch,#lll//Oll,', ./llsslls clla/i/]Ls ,i 140"C.
Z I ~11~Iiq '~I ,A! E ~ F,I S I~1LI, N G
l/Ill HIIIc t'lllt'l' S('llu'urA't/HI-Scqrcq, tllOl/,~ll/clllmh' It'l/I dr' qt':t'i~ll, ,h/l)' dlu t'l/It'~ l/,~'ct/t' Zltsallll//eltst'l:/tl/q ll~',~ ,~.'VSlelll,S Gol, t-SIh:ml/I hel 177~ AI ". I1¢!1I Nucll ,qh.s'cllrel'A('ll eiiler L,qllUrl/ll!l t'//lt'~llS('ht'l' ZllSal/IIlle/l,~el:I/II,# al/S del /ll/,~S~!lell Phase hlhh't slch ~'l/lt' /tll.~'~'ll///l!l al/S (hlht l/lid Ulller Ill¢la.~'hlblh'll PtlllS~' ( !lUllalllll "~5"') Dlu i~ Pllase hal ullle Zllsal// IIIt'lll~'~'l :llll,~ I I 011 t'[ll'¢l All IS/Illldt'lllt'lprlh/ll'hlllll~l,Y~'ll~' INTR(
)1 )1.1( '"t I( )N
(3uld and ',,lllcLm are almost totally imn|14t'll'dt' irl lhe ~(dld ,,;[ale I': They lorm a eul¢clic ut ab~l.iI ~7()"(.' and al a c~mpo.41tltm which ha4 becn variuunlv reported u.', t1(), IN6 ;ind 1'7()ul ",,
Str//~/llr
B¢I
I/It1 a = 7,,42 ,~', b = ~, ~ ~ ,.1' I/Ill/C = I I, I0 ,4
Rt.lllllllt'llipL'l'tlfllr
l/I,~,~'/IZll( 'l'f Itlllt'/hd/~
IlOt']l
lilt'hi
dl,S'SO:llUr/
I'o//s/ll/Idl!l~'
Di,s',s'o:lallOl/
u'/o'dt' all Spallell hal I ~(I" C i/lid all /~Olllpa~(te/ll i~l,II,'rIiIl he/ ¢411' t." b,,ohl/cllle/
'.,llic(m ~ ', K l e m e n t ¢1 al ~' h~l~,C r t ? ~ r l e d lhal an aun~rphou.4 material 1,4 I'~rmed when an alhw c~mt~llnlng 2 ~, al ",, .,+lllc(~n i,,., quenched Irwin1 the hqtlld slalC, and that this tratz,41'~rnl,,,, sh~wlv al r~(~un lemperuttlre illh~. LI cry,,.;talhne phase ~1 cuunplex ,~lrClt'lurc Slmlhlr ,~b4t'rvatl~m,~ wcrc made by
[Ihlli'tltJl+, ' %'t H'III'I' l/lit1 I-~llqllll'l'llll!l ,*mt'r. an N,.'wlv I . r MelJl,,
lilt'Ill(l('/
Sttllllh', elm' d/'/ll/lU Oburfl/h '/lellscllll'l// d('r i~-Pllase. dl'r Rusl der Pl'ohe ts/ I('lhl('ll Se/hS/ /laCh Ulll('lll .lll/ll'
Mel.ll,, Purk, q )Prop ,JmJ I-,I,,evwr Neqmua ,4 A
Luu,,;.nrw
Prmled m IIw Nelherhind',
N,,-I
<_; A ANDI-,RNON cl ,<31
Prede+..'kt el ,tl ~ tJ,',;ll'lgan alloy ~,,'~,+nlaliililg 2() at ".. ,',;fllC~m, und Ihey ul,so ,,,+howed lhul the c~,tlplex crw.;talhne pha,,..~' ~.'ould he ~blalned dtrecllv by u,'.+mg u m+mewhat hw+,er quenching rule Neilher <~1 Ih~*se two gr,~upn ~1 worker.,+ carried ~mt del'm=t~ve ,~lructure delermmatton+, but Predeckt t'l +.d len tal~vely c
ME,A,",;I.I R E,ME N T' l tF, 'THF E',IJ'TE,( 'TIC' I"I_)M P4 tSI T'l( tN
As a first .'+lep Iowatd'+ e,+labli.~hing the true eute~.'lic c,~rnD~.~fl,m HI was def.'Baled Io study alhw,, ~,1' lhe lhree ~.'.,~mp~,+tlt~ns pr~p,~sed b~, Ihe earlier workers
mentioned ahLwe, it, t11), IN(+ artd 1'7() ut ",, .~il,.'on Appn~prmte :lm~unt,+ ~1' gold wire and powdered ~ili~.'~n b~th o1' qqt.)qq,, purity, were +.'ulel'Lllly weighed ,~ut iiiI,) quartz luhc~. ']-he tube.,.; were eWlCUaled and mealed, and Ihen placed in a I'urnace ul II)()(I"C I'~r 24 h,~ur,,+ Finally, they were alh~wed h~ ~',~,~1.~h~wly to r,~,ml lemperulure ii1 tile ful nu t.'e ]-he mt+.'r=*.~lruclure ol each mg~,l wu'+ curel'ully e ~a m reed hy prepar t ng D ~l=,+ltedand el~.'hed '.;ecI i~m.,.; A rtllXlLire ¢+~[.'t4.]Llet~LINpCHa,',;,',;iLIm,~dlde .'.+;Oh.lli(t,tt and lib.'lure ~1 t,~dlm.' wan used u.~ an elehanl ]-'he ulhw Ihe tipper '~Llrl'a~.'~:
~, NI]IL'(Itt
Fq.+, I An c~;Jmplc ~1' Ihe *.'hie,,,1~ ,,+L'rq'~l,dru='lure h~rrned b,~ eule~IH dL=L~Pnlr~,,,=l=,~nm a p~dd ,,d, ~n alh~y ( . 2(1(I) /Ihn+,l
5,1 L.+I , ,l(iqll)g'~_~l)
El I'TE,I_'TI( ' DF( 'l )MPI ),.%1Tl( IN IN (J( IL,I )-NIL II 'l_lN NY,N1F,,M These lentlil,~ wele inlelpreled hi mean thai the alhwn c~mlaulinl? tl () and IX6 al ",, sillclln were hvpereuleetle alh,ys, while the alhly L',lntalnulg, 17() ;.it ",, slllclm was hyp,)eutecllC Thus. lhe nlhc~m h.Jnd ~m Ihe uppel nurlacen Ill' each Ill' Ihe Iwo hyperel.lleelle alhws wan relecled Irlml the INuid phase, and II(lated hi the nurlaee, as each alloy was c~._)led hlwards lhe euleclw lemperalure Smnlally, i?,~)ld wa~,~ rejecled by Ihe h~pl)euleelic alhw and HI lended I~, ~,?,ravilale hlwardn Ihe bl)llt)m ~ll Ihe specimen t'tll~ inlerprelalHm implied Ihal ltle lille euleL'llL' ~.'llnlp~)sllllln was II~ be h)Lllld s~llllewilere helweell
171) alld IN e, LII ",, .~lllcon AI,~), II Inlphed lhal Ihe chlne.~e ~wrlpl ~lruclLire I'(lund III all Ihlee .~peclmem~ shlluld have Ihe ellleCllC ci,inpli.Mlion Malerlal Iree Irllm ellher slllom parllcles~ir I?,(dd dendrlle~ was lhereh,re laken h . wet chenllcal analy~,an I'r~ill~ the ,,,ec(md alld Ihlrd speellnens Tile analyse,~, which were calrled ~)tll al the Bridt?,ep~irl Te.~llnL.~, Lab,,,, Brld~,epl)ll, (_'~mn revealed ll'lal bl)lh nanlples cl~ill:lilled 17q ;.it ",, nillom T'hn.~ Iheil iN Ihe llue L'(IFIIpll',lIl()ll Ill' tile L.,idd slllelln euh.%'IIC T'~l check Ihin result a specimen cl)mallllll~ Ihi,~ ;inliH.illl ill' ,SlIIL'(H1 wan prep;.lled tl,Sllll#, leL'hlllL1Lle~, Mmtlar Io lhll,se de,scrtbed ah(ive I1'~ ,slruelute clmsmled s~,lt'lv i)l'ehlnene ,~crlpl wlli~ m) evidence whal,,i,ever o1' relecled slllc~m ~)r L.,idd
~"~
aln~ healed h) I()()()"C and e~,fled hi ~()(Y'C In lhe lurnaee, bul was Ihen quenehed inhl iced waier When Ihe euleclle alhws were examined melalln graphically II wan I'uund Ihal Ihe lhree o,fllnL~ rules had pruduced ihree readily dmtlngul,shable nl~)r ph~flot~le,s 'The Firm e~hlblled, a,s e~pecled, Ihe chinese nerlpl slruclure The ,~ec(.id exhlhlled solne chinese scrlpl ,~lruclure, ailh~)ugh ~lrl a rmer ,~cale, but al,~ eonlained area,~ ,~1 an apparenlly lamellar slruclule The Ihtrd c, mlamed what appeared hi he a i,,J hke slruclure, the rl)ds having dmlnelern ill Ihe order ~ll ()'~ I~ II is ,fl' e¢ltirre dangerllLi,~ Io alleirlpl h) deduce ltueedilnensl~mal .~lluclLires I'rl)lll lwll dlinell,~l~lllal lnlcro,?,raph,s, and s~) Ihe,se de,~erlptllmS .~h~,JId he re~arded an lelllallVe The Ihree h~pl)euleclic all(w!, wele Iound h) have .Mmilar slrtidtires excepl lh;ll primary g,~fld derldrlles were ,lh.~erved Ill ti~e lW~l lhal wele m)l quenched The IWu qtlellched alMy,s were sllvel irl coh)r inllnedlalely al'ler quenehln~,, hl.iI Iurned glfld ~)ver a period ,,l'~everal h, lur,~ The alhw,s Ihal were rrl, tre sh)wly c(l~ded were always ~()ld in ~.'lll(,r KniIill~ lillCr(lilardlle:~s mea~,tlrelnelllS were carl led ~)tll lilt each i~l Ihe eule,:lic alhw speeimem. The mean values i)l~lalile(J hlr Ihe i)r.~l, se,.'nnd and Ihird specllnen,, wele NNg I t l and 2h I-)
'n-lE' SI-RI_IC'T'IIRF' ANll ('I)MP(ISI'T'IIIN (_tf THE' ~'~ PHASE'
M()RPHIILI_I(51FSllE, A FI_ITECTI(' AND A HYP(I[I.ITE'("TI( At L(_IY
The nexl phase ~ll II~e inveslll?,all~m was aimed al i)hlallllll~2. ~)ne ,ir nil)re ill' tile el~lnplex ery.~lalllne pha,w.~ rep~rled m lel'!~ h-N a.~ being h)rmed nn cluenchin.p, hquld 1..,.~fld-Mhclm alhwn Fllr lhm purp.,se Ihree specimens o1' tile el.il¢cllc alloy (1'7 i) at ",, nllnc~m) and tiuee .~peclnlelm ol'a ilypl)etileCllC alhw (I '7 () at ".. Slile~m) were prepared These were L:,r,luped mh) Ihree I'~a.:~ ~)1' speem~ens each p a . eIUINlSlii112, Ill' ()lie el.lleL'll~.' and ~ne hyp~)eLlleellC speciinell The hypl)eulecllc .~pe¢llrlell~ were In eluded :,o as Ill e,(ph)re Ihe po.~nlhilil~ lhal exce~s L.,,idd telected I'r~.~l the liquid pha,se ml~.,hl prlwlde .iwlealmL.,, sfle,,, I'(. one ~)r .)lher i~l' the phase,~ in the eLlleellL' iniXltlre Iherehy ehanplnb~, the mllrph~d~)L~,y ill Ihe rnl~lLire The lirsl pair wa;, healed Io I()()(~'(.' and Ihen alh)wed I()Cil,II II1 tile furnace, lU.~l a.~ Ill lhe previous e~perllllelll,S Tile Neelmd pall was healed to I()()1)"(_', el.ded In Ihe lurnace hl '~(M)' (.', and Ihen all~)wed hl air ~'l~,,I hi r~)ulrl lenlperalure TIle lillrd pair wa,~
The nllver L'~,l~r ,~1 Ihe qklenched alhw.~, and Ihelr d,.'veh~pmenl ol'a ~).~fld ,.'~l~r ,,n .~landm[z at r4,,n leml~eraltlre, ,suL.,,izesled stnmL:lv Ihal their slruclure wa,, i~llwr than a etllectle intxlure (ll j?l)ld and slltc,ln Behaw~.Jr ill ttus lype had heen rep~)rled by Iwl) earlier gr~lul.v~ ill'wllrker:, '"~, whll :dl(iwed that Ille ~.'l)l(ir ehLinl).e IS due h)lhe dl.~NOClalilm Inl()[.'4 fld aild ,,dtclm i)l a sull'aL'e laver ill i,ne 4,1' lhe c,,nplex ~.'l V,slalhne pha,ce,~ I'llrmed un quenching Furlher evidence piHnlltll. ~ in lhu ,salne dlr¢Clllm ~a:, ~lhlamed I r(.n a ira,re carel'ul ,~ludy ifl Ihe ;,IruL'll.lres i)l Ihe quenched ~peL'llllel'l~.; tllldel Ihe iIpltcal mwrll,,e~)pe F'ms[, ii wa!~ hi)treed Ihal Ihe vldume Iracl,_m ~ll Ihe hL:hl rl)d hke slruelure~< aSSUlrled hl he g, fld, was much :¢lnaller than Ihe vlflume Ir;.ICtl~lll ~ll' l:-'.,Id Ill the chlne.w .~erlpl ~lruelures Secondly the l|ialrlX pil;.i.~e clearly did lll)l C(HISlNt i)I sill¢lm becauNe II had h)ll ,Nlrlm~.?, ;.I mela]lic iLislre I1 waslherel'l~relenlaliveiycllncluded Ihul the Mructure i)l Ihe quenched speclrl|ell.~ c~in sl.~led i,I ~,~dd rl)d:~ embedded in a inalrlx (ll ~,,Olile iflhel pha.~e C~lillaillili.p. blllh gl)l~:l ;.ind MliCIHi T'his ,~lnh'p ,%'~1£5.1 ,7(I,~7J)Nt_,~()
g~'l
(_; A A N D E R S O N
malrlX wag designated Ihe ",) phase" bearing in nuncl that Its d e s l g n a l l O l l might have h~ be c h a n g , e d II II lurned ~ut h~ he idenllcal with ~me of lhe phases already rep~rled m Ihe hteralure. Nexl. the crystal slructure ~1 Ihe ,) phase was studied usingX ravdiffraclum teehmques r)ebyeScherrel D~wder pallerns were obtained I'r~m rdlngs using copper K,~ radla lion and a n,ckel Idler (F'lg 2) S~m,e ol Ihe rnany hnex on these patterrix L'~Lild readily be idenldled as due h~ pure g~ld The re mamder, due to Ihe ,'~ phase, could mfl readdv be indexed. T'(~ oblalrl precise values ~11 211 I'm each r'elleclum, dlllracl~meter Irucex were ~blalned using speeunenn p r e p a r e d by gluing I'~hiu,,x to a glass slide 'The besl dll'l'racll~m palterus were ~blulned after anneahng Ihe I'lhngs h~r I hour at I()()'C 1o rein(we 41rains 'T'his Irealmerit sharpened each peak but did n~H change the nalure ~1' the palter,, In indexing Ihe hries due h~ the 0 phase (Table I) il wax h~und Ihal many o1' lhe sh_ml:,.er ones c(~uld be aco)unted I{~r (m the b;.lSlS ol a prnlrullve cLlbnc .',,Lib cell wilhd = "~q()A The remainder aree~mslslent with an orlhmh~mblccell wdha ='7 g2 A.h = 5 '~'~A and c=11.16 ~ These wilues ca,, he expressed ahn~st exactly as o = 2 , lql) A, h= x,,"2 , tq(I ,,~ and c= v"g , t qt) A 'Thus tile ~rlhorh{~mbic cell Ix ba~ed ~n the p r i m i t i v e Ctlbl~.' sub cell and has e,ghl times its wflume T'he mde.xmg m 'Table I has been carr=ed (u.=l uMng mulu,'=llv ~rtho.g~mal axes wlHch are parallel to the [ I()0], [I II)] and [22()] direclums ~1 Ihe cubw stihcell 'The lalllce par,'lmetel ~l'lhe cubw sub cell is very s,mlar I~ th.'lt ror pure g~dd (40'78h ~,) A unit cell (~1 pure g(fld c, mlams I',mr ahmls of gold, and Ihus II seems reas~mable h) assume Ihal the CLIblC s u b cell c~mlams ~me unil ~1 Au~Si, ~.e. three ah~rns ~l'gold and one ~1 slheon II lies is s~ lhe tinll orth~rh~mblc cell e~mlams elghl Au ~SI umlx. The appn~xunale c(,mp~sltlon (.ff tile t~ phase was delermlued using a quantllalive melalh~graphlc technique An enlargement ( , .S000)~fl'a mlcmgraph uf orie ~d' Ihe quenched eutectlc alloy specHnens sh~wing a leg,i,m where Ihe gold r~dx were normal h~ the xurlaee was prepared (F'lg t) The enlire
~'I ~.ll
TABLE' I INDEX, IN(, I)F LIIE'FRAI'[IIIN LINEN DIJE II) THE ~ F'HAN[ IN A 1211ENI'HE,Li L,IILLI-SILI('4)N FIITEi 'II1' ALLIh'
2fl
I.t,'.~t I'
,1~,;i
,I,~,,~,
(hi, I)
2 / N' ~2,-lh'
V ~ea k Medium V v weak V weak V weak Weak SIr~mp, Medium V ~ Weill~
It ()6h ()I~I
i) l)te~ I) IR)
(2IX)) ((12(i)
(114 ~
1) J,4,4
(11),4)
()1'~'~ (llhl (I I 7t~ (I Ig7 (I 2hi () 2N'~
()IS"~ ()lhl O 177 (I Iq~ 0 2hi l) 2N'~
(;()1) (OI4) (I 14) (22(ii
V v weak
O H)N
l) tl)q
(,4tlO) ( ; 21 ) (t22)
'~2 1" '~'~ N
V we,Jk V v weak
() ~2t~'~
l) lr, N
(I }07 t) ~2t, (I 1,~~t,
(~1,4) (,412) {2 ;I)
'~6 7
V v WC,lk
I) lgl)
(] tgll
(11'~)
'~7 7'
V v wL'ak V v weak
II ;q? Ildll)
(i t'41 (I,4()N
(,421)) (Ill/)
V v weak
(I d ~N ( 14 "*,-I
{I ~h) (,4 ~,(i)
;,4 (~"
;S ;" ;t~(l" ~7 7" ,40 0" ,4h ,4"
,IN (; '~1) 7'
'~q 2' hi ()'
t, '~ 8" ,,t~ 8"
V weak
l) ,4 ~,,4 I ) ,4 '~,.I () '4 7h ~) ,4'-)1'1
V ~wak
hTq"
V Wedk
(-;=1tl' {,.I 2"
'~t ¢d l ll m
V ~,¢al'.
(i ,-I 77
(~,~h)
(I ,4q,4
(,41 'q
() '~10
0 '~(Iq () '~12
(IX)H) (I ;",)
()%2%
()'~2
(l),.lll)
micr~graph was weighed, and then the areas representing tile r~ds were c:irefully cut out with u pair ol'sclssors The remainder ol the mlcr~)g,raph, i e. the part lelt alter the areas representing lhe rudx had been rem~wed, was weighed again. From the resullx o1' these weighmgx the v~flume Iractmn c',f rod,; wax calculaled a,ssummg that the fracture q~l the mu.'ro graph representing rods wax equal to th=x w~lume I'racl I~ln 'T'hen, I r~,n I tl=s W~ILIme I'rac tu m I he corn po silum ~1' lhe a phase matrix wan calculaled The result L~blamed w:lx that the ,'~ phase c~mlainx 2,-I 9 a[
". stiletto
It is dllflcull h~ esllmale the accuracy ol Ihis melh(~d ~1' determlmng Ihe composition of the 0 phase If the mlcrogruph lruly represenlsan array of gold r~ds, exaclly nurmal to Ihe sLirlace, in a mulrlx ,~1' the ,'~ phase. Ihe aXSLimpll~m made in w(~rklng IH.II the wflume Irat'llOn or D~ld m exactly rig.hi II'the conclusum that Ihe slruclure c~msmls if,l, I'iL ,'
'll, 'l[p' '% I,!,~1 ' J"Ip ~ A D e b y e
.~;Lherre[ X r=Jv dillr,Jciion p.'ilh.=rli ,~hl.iln~.=d w i l h
J q u e n L h e d h q u l d gold
ii
,,lh~.on a l l o y ,~I lh¢ I.'LII¢¢ IlL ~.oml.~O';llliHi
,'llah'l .~'l i E).I , 7 (liT71) 8 1,-~-~(I
El_ TE'('TlU I)t( qiMF'(U,',,ITII)N IN U.,()LD SILI('UiN NY~TI-.M
N7
Fnl~ I The rrn~rq~,.,IrlUi.'ll.lr9~,I a quen~ht'd f'~dd !,iln~~,rl i'lUh~li~ Jll,~y ( . '~OAX)) ~1' r~ds happens I~ he wr(~n~, and, liar example, we were aclllally ~,b,~ervin~,, secltc, n'~ ~1' spheres. Ihe as.sttmplt~n m ~ltll quite .p,~d and pr~bahly led t~ n(~ rn~re lhan a lew per c'e111 err,)r We d() nOll h~)wever, Ihtnk LhaL tt us very hkely ihaL the micro f~raphs have been im.'~rrectly inlerpreied Atl~lher p~ssthle source o1' err(~r was varuattun tn the Ihtck ile~,s ~r derlsily ol Ihe ph~h~l?.raphlc paper used in preparmL.'. Ihe rnlcro~.raph, but again tl ,~eems un likely Ihal Ihmexceeded a I'ew per cent Finally, Ihere may have heen s~me error irl c ulltn)..,. ~ttl Ihe requited parl,~ ~1' Ihe micro.graph since Ihere wa.~ some blurring ~1 lhe r,~d-malrtx tnterl'a~.'es because Ihe ~ptic'ai unler(~e(~pe wa"., heiru?, used near sis iumll ~1 re,~dulu~m ( )verall we reel thai i1 t~ unhkely thai an err~r ~1' m~re Ihan ± I()",, wan rnade m delermmnnl?. Ihe ,~ilicon e~mtent ~1' Ihe ,) phase T'hus we estlmale Ihal Ihe '..;iIi~.'~HI¢~lltenl i,~ m the ranlg.e ~1 2'~ ± 2 '~ al ",, Thin appr'~rxnmale determnnaln~m ~,1' the ,'1 phase c~rnp~;,ttton Iherel'~re leads u.~ h_~ lhe con clttsi~rl thai it i.s based ~m the h~rmula All ~Si
DF,I"(.)MI"(_),.%11ION (.IF 'T'H[' ~:') F'HASF T~ ~ttudv the dec~mp~stli~m ~1 Ihe ,) phase al elevaled lemperalures fihngs were prepared I'r,,n a quenched euleclle alhw specimen Irwin1 which the
Iransl',~lmed ,~urlace laver had been remm, ed 'The I'dlnL~,,+ were annealed at I~,(.)"(Y and at intervals they were c'ouled It+ r ~ m temperature tt~ lake Debye-Seher rer pa tier n.~ SLIL'~.'e.SNIVe palter ns .~h~~w ed weaker and weaker ,'~ pha,~e Itne,~ until, after '~ h ~ u r s a t I ~ ( ) " C , ~ n l y Ihe Itnes~.'~rtesp~ndlng Io pure .p~dd were ~bserved II m assumed Ihal re Ileclt~ms I'r~m lhe sdlcrm, wtHL'h must have been presenl, were ahs~rhed by Ihe guld F'urlher expermlenls using an anrleal,nL:, lemperalure ~1' IIX)"C ,d-i,~wed Iha[ at [hl'~ lemperature Ihe dts.s~¢ta It~n wan .~ldl mc~vnplete after "~ h~ur~ AI 2()1~ L' c(nrlplele dissoelall~m ~,.'~.'urred m nh~,ul 21) rrlmtiles T'~ stLidy Ihe dlss()ctalhm ~1' Ihe ,'~ phase in hulk .'~peetrnens. a number ~d' bulk narnple,~ were annealed al ~.-II)"(J h~r perl~ds ~ffup h~ ~ h~urs E'ach ~ne was examined melalhLp.raphlcally, and Ihen mtcr~ hardness measuremenln were carried oul ~ll it and I'tlln~.s laken Ir,,n it were u~ed h~ ~htaln a DebyeScherrer pullers T'he nletalh~.raphl~.' resullnsh~wed lhe hleakd~wn ~1' the quenched :druciLure inh~ irregular needles ~)r plalelels ul' stll~.'~m in a g.~ld irlalrlx (wet a periled ~1' ah~tll 2 ~ h~l.lrs (FIp ,4). Alter ~ h~tir.~ Ihe ;~,lll,..'~r'lnl~rph~h~gy had ehan~ed to irrel::.ular ~.lnbules ~1 Ihe order ~1' ~ lU m dtameler The K n o n p hardness lell Ir~m a value ol 2t~ In a value ~1 '7~ .'~l'ler 2 '~ h~urs, and Ihen decreased sh~wly I~ f,N aller '-) h~ur'~ The Dehye-Seherrer pallerns ,~l.lur
~_',t tt.i
'(l'~71)N; ~()
NN
G A AN[IE,RSIIN t'l ~//,
F"~I:, 4 The ITIICrOMrul.'lure ol ,.I quen~.'hedp,l~ld-.s=l~.',~nelJl¢CllC allm, aller ii had heen annealed al '~,-I0"C Ior 2 ", hour,,.,Io c,.iu,,edu,,~,oc=a lion ,tl li~e ,~ pl~u:ie ( . klili)
,d]owed Ihat the dnss(~cnatnon was complete ai'ler 2.", h~lu r,,, A quenched specnmen wa,s set .'mnde in the labora tory I'~,r ~ne year so as Io study the ro~m~ lemperature slahility~llhephase Ilwa,sl'(~undatlheend,fl'lhis period thai the dissociation was .,,;till restricted h~ a Ihm surl'aeelayer Thus il seemslhal the,~ phasei,s slable al r~.~m lemperulure even iwer a long p e r ~ d ol lime
E)lgCl.l,ggl( iN
II ~,~ w~rth c~ms~dermg why Ihe pubhshed value.``; ~fl' the eule,:tp.." ,.~(.~,ml.~,~'.;~l~,n'~ " ,~h~,w such a large spread ~,I' values, alid whether lhere are .,.;(,urid rea..s,~ns lur heliewn~ lhal lliese puhl,,.;lied value.``; are nnc~rrecl and Ihe une derived from lhe presenl wllrk c,',rrecl 'T'he work ol E)~ Capua ~. wh,ch led I~ a value ol tl l) at ",, silicon, was carried ~ul nearly hall a cenlLtry ag~ using ,silicon c~nlatntng ah~lul ~,",,~*ltrnpurtltes I t c a n t h e r e l ' o r e b e r e l e c l e d ~ t l l h e gn~,unds lhal the trrlpur~lws substantially trilluer,.'ed hm re.,,;Lill T'lie value ~I' IN h at ",, ,~dlc~m pr~,D.~sed by Heath "~and llie value~,117 ()al ",,,,.,dp,.'~m pr(',p~'.; ed by Gerlaeh and (]~el" bolh he wHhm less Ihan I at % sdic~m ~ll'the value ~1' 1'7~ at ",, sdp.'~m derived Irom Ihe pre~enl w,~rk 1-'he degree o1'
dmagreemenl belween Lhe Ihr'ee resulls is iherel'~re nol very greal Healh eqmhbraled an alloy near the euleclJC c~mip(,,rlll~m at 3N()"C, l e aboul I()"C ah~we the euteclie lemperalure, and then quenched iI into cool od A chemical analysl,s, carried (lul by an un,specil'led technique, was Ihen carried OLll on lhe I'rozen liquid. There m an mherenl error m Ibis technique ,~ince Ihe liquid in equdlbrlunl with excess L.,,~dd or silie~n II)"C above [lie eulectlc tern peralure in n~l prec.sely of the eulecl ic c~mpo,ml~n I1 i,s lherel'ore coilceivahle lhal I'~r Ihis rea,,.;~l'l Healh's result cl~uld be m error by as much us I al " . ,',;IhL'on Oerlach and (Joel used Iw(~ melh~ds Io determine lhe eulecti¢ L'omD)MIl(m. First, Ihey carried ~)ul c~,~linL.~, curves and ~blamed p(vnls on Ihe liquldus curve I'~)r ,~everal alhws SecLmdl.y, lhey u,~ed a penelrall~m lechmque which gave pq~inl.s cm the hquidus curve on [he ,~ilic~m rich side o1' Ihe euleclic comDl,~H..m Thin lechnlque Hivolved placing a thin layer ol'guld ol kn~wn Ih~cknes,~ un a slab ~1 s.hci~n and e q u i h b l a l l n g at .some [einperalure above lhe el.lleCllC lemperature The g~dd reacted wHh lhe sdic~m t(~ I'~m~ a hqtud phase which, being ~n equ.hbrium wilh .s~fl~d ,stilton. had a c(imp(~sili~n delermined by Ihe D~sili~m ol Ihe hquidus curve ~n [he ,~lhc(m rich s,de ol' Ihe euleCllL' comr)~slll(m at ,ll,lh'P ,%1 FInl , 1ll971)S~-~)0
F.I.IfE("TIC IrE( ( IMP( ).HIIll IN IN (J( |L D-.~I L I( '( )N SY~TE'M Ihut temperature. (_)n c ~ l l n ~ , sllle~m was redepos fled on the slah Lintel Ihe eulecltc ~.'~rrlp~l,.;ll,l~ln was reached, bul subsequenl melalh~.p.raphlc ~lbserva l,_ms enabled Ihe arnounl ~1 s i l i o m m soluti~m al the e q u i l i h r a l m g temperature hi be determined 'T'hts was p~.ss=ble because lhc mlerlare at which the slho~n b¢~.an I~ be redep,),,,,iled C~LiId be dlscer'tled n~etallog, raphwally T'hus Ih¢ c~lmp~.,.,,llon ~d' the liquid phase m equiltbr'tum wflh s~fltd sdw~m at the equdtbrali~m lemperuture, +~, Ihe i+'~silt~m ~ll the liqui,Jus curve at Ihal temperalure, c~uld be ca h.'ulated The restllts obtained by these Iw~ meth~ds agreed qtule well, and (Jerlach and (.]~el were lherel'~lre able Io extrap~dale the l,w~ branches ~fl'lhe hqutdus ,..'LlrVe .'.a~ Ihal Ihev intersecled at Ihe eulecllC c~m|p~Sltlor! 'The exlrap~dalrons e.~tended over aboul .~ al ",, s,llc(m ~m the ~2iI)hJ rich side ~1' the euleelic e(H'np()s,l,lOrl and ub,)ul 4 al ",, sillctm ~,HI Ihe s f l i o m r,.'h side 'The~, eslimaled Ihal flus pr,~cedl.ire led h~ u pr~bable error ,fl' ab,~til +_() ~, ;~t ",. ;,fl,.',m m their delermmaltem ¢~1'Ihe euleL'liL' c()mp()Sl[l()n 'T'hls C(HIClLISI¢)II ,S, h¢)wever. ,~l')en h~ ,iblection ,m Iw,~ gr~unds Ftrsl. their hqutdus line ,m Ihe sd,.'~m rwh side ~1' the euiecllC d(~es ii~H appear h~ be Ihe besl line I hr=~u[.~.h Iheir experHt~enlal p~mlls T'he best line w~,Jld brant:? the eul,eclic comp,~silion shghlly lurlher over h~ Ihe silir, m rich s,:le ~1' the dtaL.,ram 'The hqutdus curve ~m Ihe t.-'.~dd rich side ,~l' Ihe el.lleCllC IS steep and s¢l the exlla p()lall(Ul (wer a ranL.,,e ()I'2 al ",, slllc~m Is tlneel lain ;it,d (.';In be adjusted s~ thai II sllll inl,ersecls the ~qher branch ~1' Ihe Iiquldus curve al Ihe eutecllc lemper~lure Seomdlv. b~flh Iypes ~1' measuremel~l.~ may have inwdved syslenlal,c eri(~rs (_'~(dlntJ curves are subl¢cl hi error because ~1 Ihe p~s.,.;ibllll v ~1 omslllUll~ulal Linderc~dlnL~ The penelrall~m technique used may have been in err~r becatlse () ~",, ;Jllllnl~t,rlv was added to the L,~ld h~r reas, ms thai were n,~l adequately explained The facl thai the l w~ sels~d',neasu remen Is i?.ave results w h Ich agree well with each ~lher d~es or CC~Llrse Sllg.L.~esl Ihal bolh are c~lrecl, hul Ihere lemalns the p~)sslbllllV Ihal this a~reemenl IS I~)rltllh)L,S and IS merely the restlll ~ll c~unparable err~lrs ,ll b~qh sels o1' measure menls ()verall, Ihereh~re, Ihere seem ht he ,,Lifl'tctenl /2r~tlllds for Ih,nkm.~ thai (Jerlach and (_~el's rent.ill mav be Ill err~r by as much ;.,.,, I ,.11 ",, siIIc,~t,rl In Ihe ;,ulh~rs' w,~rk the fact that exaclly Ihe same value h~r the euleL'llC ~.'~)lIIp~Slll~)n was ~)blatned usn|~ l~.raVllV seL2.reL.~.all~mlechnlques Oil allow, ,m b,~lh ,,ide~.; ~fl' Ihe eulecllC c~mlp~,~ll,l~m i,~ slr~m!?
~c)
evidence lhal lh,s value is Ihe c~rrect ~me Wel chemwal analVst,s Is adequule Ior delermining the comp~nlli~n h~ l,he nearesl, I) l al ",, slhc~m, and the analvllcal lahoruh~rv which carried ()LI[ lhe arlalvses has worked with l,h¢ aLilh~lrs iwer a periled ~fl' .several years and been I'otirld h~ be reliable It IhereMre seems reasonable I.~) c~melude Ihal Ihe wllue~d'l'7 ~al ",,silirorl I'~lr theeuleL'tncL'omp~sitiqm ~>blalned m Ihe present inveslll.,,all~m in Ihe o~rrecl ~me, and thai Ihis is Ihe I'lrs[ lime thai a precise measurernenl ~1' HI has been repe, rled Indeed Ihe fact Ihal gravely se[~,regalion w~rks ,.;~l well in the L,.idd-stl,c~m syslem has enabled the ei.ileclic c~lm p~sitt~m h~ be established wtl,h an acrtirary which tl, in diMeull t~ achieve m ~l,her ,~yslems 'T'urnlng. rlow Io a dlscU,,,,Sl~m ~1' the ,'~ phase, it in pelllnenl to enquire how the resulls ~1' l,he presenl w~rk can be reconcded wdh Ihe w~rk ~m quenched g~dd-sdtcon alhws !h~ be fllund ,n the hl,eral,ure F'lrsl. since ii ,seems lhal n~ ~l,her w~lrker's have re p~rled the exlslence ~1 an ~rthorh~mbtc phase. II ',;een,s appr~prlale h~ retain Ihe des,l.mall~m ,) s(~ as h~ cllstm~,u ish Jl from all ~l'the ~lher phases rep~rled Set, redly, we InUsl dISeLISS why we have found such s l m n g evtdence h~r l i a r phase whde everwme else has lep~rled phases having rn~re c~mlplex cryslal slruclures ()ne p~sslblllly which has been sllessed by Dtiwez ~" and ~thers is Ihal the phase Iorm~:d ~m quenchln[~, a liquid alhw depends SellSll,velv on the quenching rule V a r i a l , m n m quienchir~g rule I'r~m ~ne laborah~rV hi am~ther Ihen lead h~ apparently e~mlllclJnL.., results. If Ihis p~inl ¢~1 view ts aceepled there Is r'i~, connlct between the varl~lus sets ~ll' resulls Ill the lllerature and ours Am~lher p~sslbllllv is thai, because we, rkers other Ihan ~urselves ~werlo~ked the fact thai a quenched alhw carl c~mlaln Iwt) phases, they tried h~ index Ihe lines Ir~rtl b~lh phases as ~me slru¢lure 'The I'acl thai Anarlthararr|an cl ~1 ~ rep,~rled thai alhws c~mlamlng up h~ 2'~ at. ",, s,hc,nn i?.ave ~me struclLue ~ll quenching.,, and alhlys conl;i,nlnL2 , m, tre than 2'~ al ",, ,.,llnc,~ll an, Hher slr~mgly suL..,,t.,eslsthai Ihns in Ihe ease A nalural explanult~m of ItHs us Ihal m alhwsc~nlannnngless Ihan 2~ at ",,snlnc~m they were allemplmg, h~ nndex a pattern I'rorn a rnJxlure ~1' I..~.~dd and A LUuqn, w h nle in a lh Ws can la nnnnl?.rm ~re Iha n 2", al ",, stli~.'~rl Ihetr patterns were pr~duced by a IlllXlure ~1' snlnc~ll and ALn ~Sn I.IHl'~rlLunalely their w~rk was n~H rel',~lted in SLIIl'iele,ll delafl h~ enable Ihls hyl_~olhesls lh~ be checked T'he I'lnal p~ml Io be oms~dered is whelher Ihe ,'~ I
M,m'p .%_',1E,,I
"(Iq71)X ~, ~'~q)
(.; A ANL)E, RNI_)N ('I ill
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pha,.;e is [herm~dynam.:allv stable near ro~)m temperalure or melastable Pr~.fl' ~1 stabdHv w~uld have h~ come Jrom the observalion that at s~.ne lemperalure gold and slllc~n wnll reacl, however sh~wlv, h~ form thei~ phase T'hee~mtmg evidence ~n Ihe dlss~cialion of lh¢ ~ phase suggesls lhal II IS melaslable, and it lherel'~re seems wine l,~ assume melaslabilnlv unltl evidence Io Ihe conlrarv m presented.
(_)ther phases .n quenched g~ld-stlic~n alhws have been reD~rled m Ihe hlerature T'hts may be because the phase or phases fi*und depend on Ihe quenching rale, wh..'h varies Ir~m ~me mvesltgal.m t~ an~ther Another D*ssnhllltv is thai earlner w~rkers attempled h~ index D~wder patlerns I'r~m] mlxlures ~I' g,~Id and theh phase, and sdi~.'~m and lhe ,'~ phase as single phases 'Tile ,'~ phase appears t~ be metastable at and near r~om temperature but this is n(fl Vet quite certain
C'( )N( 'L.I.!,~II_)N ACK N( )W L,E'L)(jE, M F, N T'S
It has been shuwn thai when a hvpereutecl..' goldsfllcon alhw is c~.fled slowly Ihrou.~h lhe euleet..' temperalure, s~ltd sdnom us releeled from Ihe hqmd phase and Ih~ats I~ the specimen sull'ace beli~re the eulecl.: ireezes Similarly, gold .s relecled I'r~.rl a hvpoeulecllc alloy and lends Io I:,ravllale 1o the b~ltom ~1' the specmlen Wet chemical analyses carried ~ul ~n eulecllc mixtures ~htalned Irom b~,th hvpereuleclle and ]lvpoeuteclle alloys using this gravnty segrat.m technnque gave a value h~r Ihe euleelnc compt~s,l.m ~1 1'7 9 al ",, sd..'~m This value m beheved h~ be the rnost accurate so far ~,btamed I'~r Ihis system and us correct h~ the nearest ()1 at
" . NIIIc()II
When a liquid eutect..' alloy us quem.'hed tnt~ iced water a mlxlure ol'g~dd and a new please whteh has been destg, naled "i~" ~s formed T'hm new phase us ~rlh~rh~m~b..' wllh ,~='7N2 ~. h=",.",'~ A and c = I I 16 A. and has a c o m p o s n t . m close I,~ ALl ~SI A Ihm surface layer ol the o phase dms~enales tntt~ gold and sdnom ~ver a per.~d ~l'a few h~urs after quenchmg hi' Ihe specimen is lell at r~.~m temper alure N~ further diss~t,etaltorl at r ~ r n temperature was h~und even after a specnnen had been sh~red for a year E)lss~ctal..m d~es take place al higher lemperalure, h~wever, anti, I'~r example, m complele aller aboul ~, houns al I'~t)"C
'T'hts wurk is taken largely from a IhesmnUsubm/[led by one t)l' LIS ( ( . J A A ) In parlml I'ull'dlment ~1' the requnremenls Ii~r the degree ~1 Bacheh~r ~1' Science m Melalltubucal F'ngmeermg al the Polylechntc I n s t l l u l e ~ l ' B r o ~ k l v n F'tnanctalsuppor[ I'~r tl was provided Ir~.n Denial Melallurgv 'T'rammg (3ranl No r)F,, ()I)IN~ awarded by Ihe Nallona] Insiflule I't~r Denial Researeh
R E FE R E NC'E,N I E R I r t l t ,~NL~ E B GEBERF .I ~ ht'tll f'/ll '~, , I (1~1,1) 7~t (' [4 (-'qlLLIN'~, R () (.'ARIN(IN AND(' I (IALLA(JH[I,I Phr~
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(3[HI Aq H AND B CiqlEL, ._~tt/td ,~.'ftltt' E/t'tltttll
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tt ~¢V KI [ M r N I r H WILLE% ~, &Nrb [t DL%'EZ, J'~'tlffll~' I ~ (1~4hO) ~t,q 7 P le'rEl_tEq'l~,l, B (" (JIF,'~;I[,N AI'~D N I (_IRANI, rr~JtL~ AIME,, .'If (l~.)tp'~) 141~
T R ANanHnaram~n H L Lu~ and W KLtmrnt, ,,'V.lm~' ?10 (l~hh) II),.11) ~ H S (['IIFN,'~,NL~D TI'RNBIILL ,I ,4ppl f'bl',~, 1,~t(1'~67)lt,dh I1) [~)L f)I'WFZ [tiJtl~, ,'~tH ,~-I~l /lluhll',, 01) (Iqh7) hi)7 II ('; A t~N/tEI.I'sEN, B ,5 f'l.'sts f'~.lvlechn.. In,,,lllule ol
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. ,7 (1~71 ) Y, ~ L~()