An investigation of the aluminium-rich alloys in the aluminium-samarium-uranium and aluminium-dysprosium-uranium ternary systems

JOURNAL

OF NUCLEAR

AN INVESTIGATION URANIUM

24

MATERIALS

(1967)

95-100.

OF THE ALUMINIUM-RICH

0 NORTH-HOLLAND

The aluminium-rich

F. DIELS

Received

paper,

the aluminium-rich freezing Al/24% X-ray

of some

characteristics thermal

Al/U/Dy

ternary

and

and

alloys

the

as UaDy~Allls.

A

Les contours ont

pseudobinery

(cubic Cl5 MgCua type) was found.

de

3 solutions

(Dy, U)A14, (Dy, U)Als

Es ist wie beim

a region of insolubility

in the liquid and

solid state was delineated.

of three

Schnitt

des Systems were found

in equilibrium with the aluminium-rich existence

to be

solid solution.

intermetallic

und

solid solutions

Comme dans le CELS du systbme U/Al/Sm une section

du coin riche en aluminium BtB d&term&&e solidific&ion careot&istiques dans

la

ainsi

de

la

A1/24%

suite

alliages

die

U.

des

&apes et

m&hodes

(Teil I) ein isosind

einiger terniirer Legierungen von

y. U ermittelt

wurden

mikrografische, Methoden

U/Al/Dy-

worden. Dabei

rCintgenograf&che und ther-

sowie

Untersueh~gen

mit

einer

angewendet. worden.

Verbindung

(MgCun-Typ,

kubisch,

und

IGslichkeitsgebiet

Legierungen im

fliissigen

System

C1.5) ist gefunden

worden. Es wurden die Phasengrenzen dreiphasigen

ist UsDy3

Ein pseudobiniires

de

micro-

Ecke

worden. Weiter

les

der ein-, zwei-

best,immt;

sin

Un-

und

festen

Zustand

drei

intermetsllische

wurde abgegrenzt. Es

wurde

Verbindungen reichen

utilisees dans cette Btude. tern&e

bestimmt

mische

DyAls-UAl2

a

radiocristallographiques, l’analyse et et la microsonde Blectronique ont 6%

Un oompos& interm&allique

U/Al/Sm

Als ternlire intermetallische

des alliages Al/U/Dy Los

a BtB trouv&.

Herstellungseigenschaften

Al15 identifiziert

& 600” C

ternaires

System

Legierungen mit Al/24

discute dans

isotherme

du syst&me Al/U/Dy

de fabrication

region

graphiques thermique

que

quelques

interm&alliques

(bei 600” C) in der Al-reichen

U/Al/Dy

~ikrosonde partie,

solides

et (Dy, U)Alg

die E~t~rr~gsp~te

(Dy, U)Ala, (Dy, U)Al3 and (Dy, U)Ala was esDablished.

la premiere

en

The phase bounthermer

The

ont 6% trouv&

DyAlz-UAl2

determined;

compounds

bi-

Bquilibre avec la solution solid@ riche en aluminium.

daries of the single-, two- and three-phase alloys were

Three intermetdlic

mono-,

region d’in-

liquide, eomme dans 1’6tat solide,

Trois compost% interm6talliques

analysis

was identified

system

Une

a BtP. d&imitAe.

L’existenee

compound

des domaines

Btti dhterminbes.

solubilit& dana I’&&

were used in this investigation. One ternary intermetallic

(de structure eubique de type C 15 Mg Cuz)

et triphas&

Micrographic and

microprobe

1967

a 6tB trouv&

in the

system

MOE, Belgium

Dy Al&Ala

system,

dloys

of Al/U/Dy

U region were investigated. methods,

discussed in the

section at 600” C of

corner of the

sequence

fabric&ion

system

an isothermal

9 June

ternary

SYSTEMS

and A. COOLS

Stud~iecentrum voor h’ernenergie,

As in the cese of U/Al/Sm

TERNARY

alloys in the AI-Dy-U

I?. CASTEELS,

CO., AMSTERDAM

ALLOYS IN THE ALUMINIUM-SAMARIUM-

AND ALU~NIUM-DYSPROSIUM-URANIUM

II.

preceding

PUBLISRINCl

drei

a 6th identifie

gefunden, sich

im

Mischkristallen

intermetallischen

dess

Gleichgewicht

mit

befinden.

Existenz

Die

Verbindungen

Alvon

(U, Dy)Al4,

comme &ant UgDys Al15. Un systbme pseudo-binaire

(U, Dy)Ala

1.

The possible existence of the following compounds has been mentioned: DyAL, DyAls, DyA12, DyAl, DysA12 and DysAl. Moriarty and Baenziger 2) report the existence of the compounds Dy3Al2, DyAl, DyA12 and

In~odu~tion

and literature

review

As already mentioned in part one, the purpose of this work is the incorporation of burnable poisons in Al/U fuel alloys for materials testing reactors. 95

und (U, Dy)Ah

den

wurde nachgewiesen.

96

I?. CASTEELS

DyAle

in the

d~Tsprosium-aluminium

DyAlz has a cubic ClSMgCuz lattice

parameter

a= 7.840

system.

structure A 3). The

with a crystal

structures of DyAl4, DyAl and DyaAl~ are not mentioned in these two reports. An

intermetallic

hexagonal

compound

structure was reported

DyAlg

with

by Baenziger

ET

AL.

Results and discussion

3. 3.1.

MICROGRAPHY

AND

X-RAY

RESULTS

The results are summarized in fig. 1. The phases in equilibrium with the aluminium-rich solid

solution

microstructural

were

investigated

and microprobe

by

X-ray,

analysis, from

et al. 4). This compound has a structure isomorphous with NisTi; the lattice parameters calculated a=6.097

from powder diagrams of DyAls are d;

c=9.534

A.

Kato et al. 5) reported the existence of a DysAl compound. This compound exists in two modi~~ations: a and p DysAl. According to the results of Buschow 6) the DyAl compound has an orthorhombic structure with a=5.604 8; b=5.822 8; c= 11.639 A; the DysAlz compound fits a hexagonal symmetry with a=%.17 8; c=7.523 8. As mentioned in part one, three intermetallic compounds have been reported in the aluminium-uranium binary system : UAl4 (orthorhombic structure) UAl3 (AU&S structure) and UAla (MgCuz structure). A transformation near the Al/UAl4 eutectic temperature of 646” C has been observed in the UAl4 intermetalli~ compound by Runnalls and Boucher I). This transformation involves the rearrangement or clustering of vacancies. In an investigation of the aluminium-rich part 7) equilibrium of the aluminium-dysprosi~lm diagram, the existence of a /3 DyAl3 intermetallic compound has been observed. According to Van Vueht et al. 9), this compound fits a rhonlbohe~al symmetry. Dysprosium and uranium are mutually quite insoluble 2.

in the liquid

and solid states.

Experimental

The base materials used in this work have purities of 99.995% (Al) 99.8% (Dy) and 99.98% (U). The main impurities are identified as Cu, Fe and Ng in aluminium ; Ca, Fe, Mg and Ta in dysprosium; Al, B, Cr, Cu, Fe, Mn, Mg and Pb in uranium. The experimental techniques have already been mentioned in part one.

100

Fig.

wi,

A,

1.

80

Isot,hermal

60

se&ion

100

w,. oy

(at 600 “C) in t,he du-

minium-~Al~-D~Al~

system.

which it may be concluded that the aluminiumrich solid solution is in equilibrium with three intermetallic compounds : {Dy, U)Al4, X(A1/34.8% U/35.5% Dy), * /?(Dy, U)Als and with 2 two-phase mixtures ((Dyt UW4; XI and (X; ,&Dy, U) &I. (Dy, U) Ale was found to be stable up to 20% addition of dysprosium to UA14. The X-ray powder data for the X compound with hexagonal symmetry and parameters CL=6.05 if, c = 14.35 A are given in table 1. The proposed composition for this new compound is U2Dy~A115. Uranium can be incorporated up to 14% in solid solution in the b DyA13 compound. Using the etching techniques mentioned in part one, the (U, Dy)A14 compound can be identified by its blue green colour. Under identical etching conditions the X-phase (U2DysAl1~) and the /3(Dy, U)Als phases are brown; it is very difficult to make the distinction between *

All

percent.

percentage

values

are

quoted

in weight

AN

INVESTIGATION TABLE

X-ray

OF

THE

them,

1

powderd&ta,forX compound UaDy3Alls (CuKa

radiation). (sir+&,)

Hexagonal

* lo4

lattice (a =6.05

(sira*

A; c = 14.35 A).

334

331

479

476

(103)

650

648

680

677;

(110) (111); (104)

895

893

(201)

981

979

(202)

1044

1037

(006)

1124

1123

(203)

1327

1325

(204)

1539

1541

(211)

1578

1584

1628

1627;

1683

1685

(116)

1768

1771

(213)

1936

1944

1964

1973;

1973

2055

2060; 2059;

2059

2270

2279

1627

slightly

microstructure

of

(205) (212); (107)

(300) (301); (214) (108);(302);

states has been observed in the Al/U/Dy system ; this range is indicated in fig. 1.

MELTING

POINTS AND

During thermal

(117)

(207) (216); (109)

2549; 2592

2621

2621

2707

2707;

2708

(221) (222); (208)

2923;

2924

(312)

(220)

-

etches

FREEZING

PHENOMENA

2582

2919

p(Dy, U)Als

lighter than the X-phase. Figs. 2 and 3 show the

3.2.

2541

2549

the

97

II

Al, (U, Dy)A4 and X, the second one, Al, p(Dy, U)Als and X. An immiscibility gap in the liquid and solid

(101) (102) 677

but

ALLOYS,

ternary three phase alloys, the first one contains

wc) * 104 245

246

ALTJMINIUM-RICH

X(U3

analysis experiments

it was

noticed that the addition of dysprosium to aluminium-uranium alloys affects on the UA14 peritectic temperature. Very small thermal arrests were stated in the region of the peritectic temperature for alloys containing small additions of dysprosium. An appreciable influence on the microstructure of aluminium-uranium alloys with additions of dysprosium has been observed. As in the case of the aluminium/ uranium/samarium system, no irregularities in the melting points could be observed. Additions of dysprosium to aluminium-uranium alloys

Dys

Us)

Al

(DyU)A14

Fig.

2.

Microstructure

of ternary

aluminium-24% +X+(Dy,

dysprosium-38%

U)A14 (blue-green).

uranium x 750

alloy:

Al (white, overetched)

98

I?. OASTEELS Al

Fig.

3.

Microstructure

ET

B(Dy, U) Al3

of t,cr-nary aluminium-22%

X

AL.

(Ua Dys Al15)

umnium-38~0

dysprosium

alloy:

aluminium +X

-f-@$Als

x 7.50

influence the melting points of the aluminiumuranium alloys (table 2) only slightly. The distribution of dysprosium and uranium in the (U, Dy)Ala compound is of interest with respect to the fabrication of nuclear fuel elements. As indicated in fig. 4, which gives the uranium and dysprosium contents in the (Dy, U)Al4 needles of a A1/24% U/5”/ Dy alloy, after heat treatment of 30 h at 600" C a quite

homogeneous distribution of the uranium dysprosium atoms was observed within needles. 3.3. QUATERNARY

ALLOYS

AND

FABIUOATION

TESTS It may be interesting to combine the effect of two burnable poisons. Quaternary alloys have been prepaxed and fig. 5 indicates that a

TABLE 2 Results

of thermal

analysis

Alloy composition (%)

Al/24

U/O.5 Dy

Al/30

U/Z

Dy

Al,‘20 U/G Al/25 U/5

Dy Dy

of aluminium-rich

Al/U/Dy

alloys.

(Cooling rate:

/ Melting point i to cj ~ “‘“F”

~~~~~~

915

652

_

678

630

_ 650

630 630

845

_

628

1109

_

628

992

687

630

I

630

Al/5

U/Z0

Dy

Al/10

U/40

Dy

/ ! j 1 i

AIf

U/l0

Dy

’

Al/20

U/25

Dy

1109

-

628

Al,‘5

U/l0

Dy

680

_

628

Al/20

U/IO

Dy

Al/15

U/l0

Dy

/ 1

836 942

and the

i

862

628

848

630

5” Cjmin).

AN 1

U intensity

L

I

INVESTIGATION

and

I

OF

THE

ALUMINIUM-RICH

1 Dy intensity

background

and

ALLOYS,

II

background

I Distance

Fig.

4.

Uranium and dysprosium

Distance

distribution throughout

after a heat treatment

U

intcnslty

and

background

I

Sm

lntenslty

the (Dy, U)Ala phase of an A1/24%

and

background

5.

Uranium-dysprosium-samarium

Dy alloy

,

Dy

inlcnsity

and

backgroun;d

A

I

Distance

Distance

Fig.

U/5%

of 30 h at 600 “C.

distribution in an A1/24%

complete homogeneity between uranium, dysprosium and samarium can be reached in the (Dy, U, Sm)Ald needles. Ternary and quaternary alloy slabs were cast in the region of 24% uranium and the order of 1% rare earth. These castings were easier to obtain than the ones with straight Al/24% U alloy: grains are finer and the uranium distribution is better. No appreciable number of pores [such as was found by Daniel et al. *)

U/1.05%

Sm/0.515%

Dy alloy.

in castings of A1/35% U/3% Gd alloys] could be detected by radiography. These slabs were hot-rolled at 600” C; the deformation characteristics of the ternary and quaternary alloys were better than those of straight Al/24% U alloy, as judged by the amount of edge cracks produced during rolling. Fig. 6 shows the homogeneity of the uranium distribution in an M/24% U/0.8% Sm rolled plate.

F.

100

CASTEELS

ET

AL.

may be concluded dysprosium-uranium uranium

that

ternary

alloys

and dysprosium

aluminium-

with

convenient

distribution

can be

obtained. Several conclusions can be drawn from the investigation of the Al/U/Dy system: the possibility

of casting and fabricating

Al/U/Dy

alloys in the A1/24% U region without additional fabrication difficulties, the existence of a (U, Dy)Ald solid solution up to 20% additions of dysprosium binary

and the existence of the pseudo-

UAlz-DyAlz

system.

References ‘)

0.

J.

AIME

7

C.

Runnals

and

(1965)

1726

233

J. Moriarty

data

3) J. H. Wernick 218

5) H. Kato Fig. 6. Autoradiograph fuel

of a rolled Al,‘24(;i, U/0.X?;, plate. x 1

Sm

4.

Conclusions

From micrographic and X-ray investigations and from thermal and microprobe analysis it

State

Trans.

Univ.

Iowa,

S. Geller,

Trans.

Met.

Sot.

866

and J. J. Hegenbarth,

Acta

Cryst.

620 and

USBM-U-1031

M.

J.

Copeland,

USAEC

Report,

(1963)

“1 K. H. J. Buschow, (1965)

Boucher,

(1959)

and

(1964)

4) N. C. Baenziger 17 (1964)

R.

and N. Baenziger,

prepublication AIME

R.

J.

Less

Common

Metals

8

209

‘) F. Casteels, J. Less Common Metals 12 (1967) 210 9 N. Daniel et al., USAEC Report, BMI 1388 (1959) g, J. H. N. van Vucht et al., J. Less Common Metals

10 (1965)

98