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Rapidly quenched Raney catalyst precursors
MATERIALS SClENCE & ENGINEERING ELSEVIER
A
Materials Science and Engineering A226-228 (1997) 900-904
Rapidly quenched Raney catalyst precursors Hans Warlimont
*:, Uta Kiihn, Norbert
Mattern
Institut fzler Festkoerper- und Werkstofforschung Dresden, P.O. Box 2700 16, Helmholtzstrasse 20, D-01 171 Dresden, Germarty
Abstract This paper reports on structures and microstructures of rapidly solidified Al rich AI-Cr, Al-Ni, Al-Ni-Cr and Al-Ni-Fe alloys. The extension and suppression of equilibrium phases, solidification and solid state transformation effects are analysed. 0 1997 Elsevier Science S.A. Keywords: Rapid solidification; Al alloys; Phase transformations; Microstructures
1. Introduction Raney catalysts, though known and used extensively since the late 192Os, are not fully understood yet regarding the relation between composition, crystal structures and microstructures of the Al-N1 based precursors and the .catalytic properties after leaching and activation treatments by which a catalyst is prepared. Cr and Fe are added lo promote the catalytic properties for hydrogenation reactions. Recently Cr doped [l-8] and Fe doped [2-4,7] Al-Ni-precursor and catalyst alloys, in part prepared by rapid quenching [3,7], were studied to elucidate the structure-property relations more thoroughly. Even though reaction kinetics were determined in several cases, systematic relations have not yet been established. Raney catalyst precursors are commonly solidified by conventional means, crushed and milled, or spray atomized. Both processing routes result in powders of a wide range of particle sizes and microstructural features. A binary industrial A165Ni3j (50 ma.% Ni) precursor may consist of Al& Al,Ni, and a small fraction of Al + Al,Ni eutectic. Since rapid quenching can lead to refined and more uniform microstructures as well as to deviations from equilibrium regarding phases and compositions, including the amorphous state, it was surmised that this could lead to effects on, and possibly improvements of, the catalytic activity and selectivity. We have, therefore, prepared Al-Ni-Cr and Al-Ni-Fe alloys to study their structural state and the * Corresponding author. 0921-5093/97/$17.00 0 1997 Elsevier Science S.A. All rights reserved. PIISO921-5093(96)10815-7
relation between structure and catalytic properties systematically. Rapidly quenched binary and ternary AlNi-Cr, Fe alloys have been studied earlier by numerous authors [9], but never under the aspects of the present study. In this paper the as-quenched structures and microstructures and effects such as supersaturation, drastic deviations from phase equilibria and particular microstructural features are treated. Subsequent publications will deal with metastable and stable phase relations of the alloys under investigation and with their behaviour as catalysts after leaching and activation.
2. Experimental
procedure
Rapidly solidified ribbons 20-40 pm thick and 10 mm wide were produced by the single roller method. The purity of the starting materials was: Al 99.99%, Ni 99.9%, Cr 99.9%, Fe 99.9%. X-ray diffraction, light microscopy and differential scanning calorimetry (DSC) were applied using standard equipment and procedures.
3. Results Fig. 1 shows the location of the alloy compositions investigated in relation to the phase equilibria of the binary and ternary systems. Table 1 gives the relevant structural information. Table 2 lists the alloy compositions determined by chemical analysis and the phases according to X-ray diffraction analysis. In what follows
H. Warlirnont
2oo~p2.~14_?p_ IO Al At.-%
et al. /Materials
20 Cr
A
Cr’
Science
aud Engineering
A226-228
901
900-904
4ooi? 7 L5 61 0
30 Cr
(1997)
10
Al
At.-%
Fe
Fe
Al
At.-%
zb
Ni
io
N3
100 Al
,
10
20
At.-%
3o Ni
Fig. 1. Phase diagramrnes and location of alloys investigated, Al-Fe-Ni
phase relations are shown for alloys cooled at 10 K h- ’ [13].
all alloy compositions are given in at.% as subscripts, all mass (weight) fractions of phases are given in ma.%, alloy numbers in round brackets. Combining the structural, microstructural and DSC results the following conclusions can be drawn for the as-solidified alloys.
(10) dendritic crystallization of y is followed by a gray two-phase constituent in the interstices, probably consisting of 0 + y.
3.1. Al-Cr
A195,1Ni4.9 (2) shows a dominating primary crystallization of CI in the form of massive, somewhat feathered grains. Residual melt appears to have solidified eutectically in small pockets in between. Also, precipitates are visible inside the CI grains. X-ray diffraction indicates that small amounts of the structure of the ternary phase z1 (Al,(Ni,Fe, -J2) occur even in this binary alloy, i.e. z1 is formed as a metastable Fe free phase. In A189.7Ni1,,3 (3) two distinctly different solidification microstructures are found side by side: (a) large nodular regions of eutectic with increasing lamellar spacing from the centre to the final growth front; (b) regions with a more or less concentric sequence of primary IC, a shell of a, a heterophase shell, and a final matrix of CI. This microstructure and its formation require further study. The X-ray diffraction results exhibit the z1 structure at this composition again. A184,7Ni15,3 (4) alloys show a feathery primary solidification immediately at the chill surface. The remainder of the microstructure appears like an anomalous eutectic
In Al,,,&, (7) supersaturated a has formed first which has decomposed subsequently into 0 + a: (40 ma.O/), Fig. 2(a), in accordance with [lO,ll]. On the chill side a light etching constituent indicates the possible formation of an icosahedral phase i which has been reported to occur in this concentration range [12,14]. Its diffraction maxima would be masked by those of Q and its small volume fraction would probably not suffice to be detectable by X-ray diffraction. A190,1Cr9,9 (8) shows predominantly a granular to rosette shape decomposition structure of 6’ (70 ma.%) and CI (30 ma.%), Fig. 2(b). Al,,,,Cr,,,s (9) shows indications of i near the chill surface again. But its solidification is dominated by freely grown 0 crystals Fig. 2(c). Since the alloy composition is almost exactly that of the 6’ phase it appears from the microstructure that the melt is supercooled by more than 200 K prior to solidification so that it solidifies by primary crystallization of 8. In A1T4,9CrZ5,1
3.2. Al-Ni
902
H.
Warlimont
et al. /Materials
Science
and Engineering
A226-228
(1997)
900-904
Table 1 Phase symbols, compositions and structures (Pearson symbol) Symbol
u
8
?
E
i
Y
Composition Structure
Al(-Cr,Ni) cF4
AWr7 mC104
Ah ?A mP48
Al&r mP180
icosahedral
AI&r, cI52
Symbol
IC
3,
Zl
3
a
J
Composition Structure
Al,Ni oP16
Al,Ni, hP5
Al,Fe,Ni, --x mP22
A&Fe mC102
amorphous
A&Fe, oC16
ti + K, Fig. 2(d), these phases are present according to X-ray diffraction. At A183,5Nii6.5 (5) primary dendritic solidification of IC appears to be superseded by subsequent cooperative IC+ 0: anomalous eutectic growth in a similar microstructural dispersion as at 15 at.% Ni. In the Al,,Ni,, (6) alloy primary rosette-like crystallization of IC is followed by cooperative growth of K + /z in the interstices. 3.3. Al- CT-- Ni In the Al,,,,Ni,,,Cr,,, (24) alloy the chill side of the foil shows areas which remain structureless upon etching: they are amorphous according to X-ray diffraction results. The major fraction of the cross-sectional area exhibits a with fine and uniformly distributed IC precipitates, Fig. 2(e). The solidification structure of 4&.7Cr17.3 (25) IS ’ d ominated by rapidly and freely grown 0 as is the case in the binary alloy with 15 at.% Cr, However, IC, il and amorphous structures are also Table 2 Aluminium alloys investigated and phases present Alloy No.
Alloying components at.% Ni
2 3 5 6 7 8 9 10 11 16 17 18 19 21 22 23 24 25
4.9 10.3 15.3 16.5 25.0 5.2 11.1 10.2 5.1 14.0 10.2 5.2 15.3 7.3 7.7
26
17.6
4
Fe 5.8 1.8 5.3 10.4 2.4 10.0 15.1 5.1 -
Phases
Cr 4.9 9.9 14.8 25.1 7.1 17.3 7.3
6 7c,fl a, 7GTl u, 7c u, IC ic,3, u, e U, e e .Q,y u, 7, ~,rr %Xl u, T, u, z, ff, z* u, 71,3 u, 7, a, I<,a, 0 K, I~,8, a
K, L, a
present. The Al,,,,Ni,,,$r,., (26) alloy shows predominantly nodular primary solidification structure which appears to consist of 7~+ 3,. Moreover, a featureless constituent appears to be amorphous according to Xray diffraction results. 3.4. Al-Ni-Fe In Al,,Ni,,ZFe,,, (11) the chill side shows some light etching crystals which may represent supersaturated a. The main microstructure consists of an anomalous u + zr eutectic. Following Fe-rich compositions first, in regular, feather-like JJ~A%Fel~.4 (18) remarkably dendrites of zr, often extending through the entire cross-section of the foil, are dominating the microstructure, Fig. 2(f). The remainder shows anomalous CI+ 21. The Al,,,,Ni,,Fe,,., (22) microstructure is dominated by primary dendritic 9 (A&Fe) with CI+ z1 eutectic (34 ma.%) which is partly lamellar, partly anomalous. On the Ni-rich side Al,,,,Ni,,.,Fe,., (16) exhibits extended dendrites of primary zl, the remainder is an anomalous eutectic. In A184,5Ni1,,2Fe5.3 (17) the primary feather-like rr is dominating again, CI+ zi eutectic fills the interstices, Fig. 2(h). The microstructure of Fe,,,GNi,,,Fe,,, (19) is practically identical. Alloy A179,8Ni,,,,Fe,, (21) is at the border of the high temperature homogeneity range of r1 and consists of a rather coarse grained, almost homogeneous microstructure of r1 accordingly (95 ma.%); the same is true for alloy A179.6Ni,,,,Fe,., (23). 4. Discussion The results show that phase dispersions on a considerably finer scale than in conventional Raney nickel precursor alloys can be obtained by rapid solidification and that the promoting components Cr and Fe can be kept in supersaturated solid solution over a significant range of compositions. First results for a hydrogenation reaction show, that non-optimized rapidly quenched Raney catalysts
are equivalent
tional optimized
catalysts.
in reactivity
to conven-
H.
Warlimont
et al. /Materials
Science
and Engineering
AZ%-228
(1997)
900-904
C
c
0.855 0
I 0.5
1
1.5
2
2.5
Fe/Ni ratio, (1- x)/x Fig. 3. Lattice parameters of the q phase Ai,(&Fe, solidified ribbons.
d
e
&
_ X)2 in rapidly
the ribbons where the cooling rate is highest. A very high growth rate v of the z1 phase can be derived from the long dendrite arms and columnar crystals extending all across the ribbons, alloys 17-19, Fig. 2(f)-(h). A lower bound can be estimated to be v 2 40 mm s-l. This is associated with an unusually large metastable extension of the homogeneity range of an intermetallic compound by rapid solidification as shown in terms of lattice parameter measurements on z1 at different alloy compositions in Fig. 3. Further accounts of this work will cover extended structural and volume fraction data, DSC and microstructural analyses.
References PI E. Rose&Laclau, M. Durand-Charre and J.-C. Joud, Res., 10 (1995)
PI D. Djaouadi and M. Besson,
h
Fig. 2. Nicrostructure of the cross section of rapidly solidified dhns. la) -%~,~Cr~.9 (7), (b) A1gO,lCrg.g W 14 &,&r,,,, (91, (4 &d%.~ (4), (9 ALd%Cr7.~ (24), (0 Gd%Pe~~.~ (1% (8) &3.6NM%.4 U% 00 ~s4.s%.2Fes.3 (17).
Gem.
Ind.,
62 (1995)
423.
[31 S. Hamar-Thibault, J. Gros, J.C. Joud, J. Masson, J.P. Damon and J.M. Bonnier, Stud. Surf. Sci. Catal. Y, (Preparation of Catalysts) (1991) 601. c41 J.M. Bonnier, J.P. Damon and J. Masson, Appl. Catal., 42 (1988) 285. [51 J.M. Bonnier, J.P. Damon, B. Delmon, B. Doumain and J. Masson, J. Chem. Phys., 84 (1987) 889. WI S. Hamar-Thibault, J. Masson, P. Fouilloux and J. Court, Appl. Cutal. A, 99 (1993) 131. t71 J. Gros, S. Hamar-Thibault and J.C. Joud, J. Mater. Sci., 24 (1989)
Quasicrystalline phases which are known to occur in rapidly quenched AI-Cr [12,14] and Al-Ni-Fe [15] alloys in the range of present interest could not be identified by X-ray diffraction but may be supposed to occur in a small volume fraction near the chill side of
J. Mater.
1154.
2987.
PI J.M. Bonnier, 5. Court, P.T. Wierzchowski Thibault, Appl. PI P. Furrer and UOI H. Warlimont, (1976) 101. 1111P. Furrer and
and S. Hamar-
Catal.,
53 (1989) 217. Warlimont, 2. Metallkde,
H. 62 (1971) 12; 100. W. Zingg and P. Furrer, Mater. Sci. Eng., 23 H. Warlimont,
Uazer. Sci. l&g.,
28
(1977) 127.
904
H. Warlimont
et al. /Materials
Science
[12] G.I. Rosen And D. Shechtman, Acta MetalI. Mater., 4.2 (1993) 177. [13] P. Budberg and A. Prince, in G. Petzow and G. Effenberg (eds.), Ternary aZZoys, Vol. 5 VCH, Weinheim, Basel, New York, 1992.
and Engilzeering
A226-228
(1997)
900-904
[14] D. Shechtman, I. Blech, D. Gratias and J.W. Cahn, PIys. Rev. Len., 53 (1984) 1951. [15] A.-P. Tsai, A. Inoue and T. Masumoto, Mater. Tram. JIM, 30 (1989) 150.
A
Materials Science and Engineering A226-228 (1997) 900-904
Rapidly quenched Raney catalyst precursors Hans Warlimont
*:, Uta Kiihn, Norbert
Mattern
Institut fzler Festkoerper- und Werkstofforschung Dresden, P.O. Box 2700 16, Helmholtzstrasse 20, D-01 171 Dresden, Germarty
Abstract This paper reports on structures and microstructures of rapidly solidified Al rich AI-Cr, Al-Ni, Al-Ni-Cr and Al-Ni-Fe alloys. The extension and suppression of equilibrium phases, solidification and solid state transformation effects are analysed. 0 1997 Elsevier Science S.A. Keywords: Rapid solidification; Al alloys; Phase transformations; Microstructures
1. Introduction Raney catalysts, though known and used extensively since the late 192Os, are not fully understood yet regarding the relation between composition, crystal structures and microstructures of the Al-N1 based precursors and the .catalytic properties after leaching and activation treatments by which a catalyst is prepared. Cr and Fe are added lo promote the catalytic properties for hydrogenation reactions. Recently Cr doped [l-8] and Fe doped [2-4,7] Al-Ni-precursor and catalyst alloys, in part prepared by rapid quenching [3,7], were studied to elucidate the structure-property relations more thoroughly. Even though reaction kinetics were determined in several cases, systematic relations have not yet been established. Raney catalyst precursors are commonly solidified by conventional means, crushed and milled, or spray atomized. Both processing routes result in powders of a wide range of particle sizes and microstructural features. A binary industrial A165Ni3j (50 ma.% Ni) precursor may consist of Al& Al,Ni, and a small fraction of Al + Al,Ni eutectic. Since rapid quenching can lead to refined and more uniform microstructures as well as to deviations from equilibrium regarding phases and compositions, including the amorphous state, it was surmised that this could lead to effects on, and possibly improvements of, the catalytic activity and selectivity. We have, therefore, prepared Al-Ni-Cr and Al-Ni-Fe alloys to study their structural state and the * Corresponding author. 0921-5093/97/$17.00 0 1997 Elsevier Science S.A. All rights reserved. PIISO921-5093(96)10815-7
relation between structure and catalytic properties systematically. Rapidly quenched binary and ternary AlNi-Cr, Fe alloys have been studied earlier by numerous authors [9], but never under the aspects of the present study. In this paper the as-quenched structures and microstructures and effects such as supersaturation, drastic deviations from phase equilibria and particular microstructural features are treated. Subsequent publications will deal with metastable and stable phase relations of the alloys under investigation and with their behaviour as catalysts after leaching and activation.
2. Experimental
procedure
Rapidly solidified ribbons 20-40 pm thick and 10 mm wide were produced by the single roller method. The purity of the starting materials was: Al 99.99%, Ni 99.9%, Cr 99.9%, Fe 99.9%. X-ray diffraction, light microscopy and differential scanning calorimetry (DSC) were applied using standard equipment and procedures.
3. Results Fig. 1 shows the location of the alloy compositions investigated in relation to the phase equilibria of the binary and ternary systems. Table 1 gives the relevant structural information. Table 2 lists the alloy compositions determined by chemical analysis and the phases according to X-ray diffraction analysis. In what follows
H. Warlirnont
2oo~p2.~14_?p_ IO Al At.-%
et al. /Materials
20 Cr
A
Cr’
Science
aud Engineering
A226-228
901
900-904
4ooi? 7 L5 61 0
30 Cr
(1997)
10
Al
At.-%
Fe
Fe
Al
At.-%
zb
Ni
io
N3
100 Al
,
10
20
At.-%
3o Ni
Fig. 1. Phase diagramrnes and location of alloys investigated, Al-Fe-Ni
phase relations are shown for alloys cooled at 10 K h- ’ [13].
all alloy compositions are given in at.% as subscripts, all mass (weight) fractions of phases are given in ma.%, alloy numbers in round brackets. Combining the structural, microstructural and DSC results the following conclusions can be drawn for the as-solidified alloys.
(10) dendritic crystallization of y is followed by a gray two-phase constituent in the interstices, probably consisting of 0 + y.
3.1. Al-Cr
A195,1Ni4.9 (2) shows a dominating primary crystallization of CI in the form of massive, somewhat feathered grains. Residual melt appears to have solidified eutectically in small pockets in between. Also, precipitates are visible inside the CI grains. X-ray diffraction indicates that small amounts of the structure of the ternary phase z1 (Al,(Ni,Fe, -J2) occur even in this binary alloy, i.e. z1 is formed as a metastable Fe free phase. In A189.7Ni1,,3 (3) two distinctly different solidification microstructures are found side by side: (a) large nodular regions of eutectic with increasing lamellar spacing from the centre to the final growth front; (b) regions with a more or less concentric sequence of primary IC, a shell of a, a heterophase shell, and a final matrix of CI. This microstructure and its formation require further study. The X-ray diffraction results exhibit the z1 structure at this composition again. A184,7Ni15,3 (4) alloys show a feathery primary solidification immediately at the chill surface. The remainder of the microstructure appears like an anomalous eutectic
In Al,,,&, (7) supersaturated a has formed first which has decomposed subsequently into 0 + a: (40 ma.O/), Fig. 2(a), in accordance with [lO,ll]. On the chill side a light etching constituent indicates the possible formation of an icosahedral phase i which has been reported to occur in this concentration range [12,14]. Its diffraction maxima would be masked by those of Q and its small volume fraction would probably not suffice to be detectable by X-ray diffraction. A190,1Cr9,9 (8) shows predominantly a granular to rosette shape decomposition structure of 6’ (70 ma.%) and CI (30 ma.%), Fig. 2(b). Al,,,,Cr,,,s (9) shows indications of i near the chill surface again. But its solidification is dominated by freely grown 0 crystals Fig. 2(c). Since the alloy composition is almost exactly that of the 6’ phase it appears from the microstructure that the melt is supercooled by more than 200 K prior to solidification so that it solidifies by primary crystallization of 8. In A1T4,9CrZ5,1
3.2. Al-Ni
902
H.
Warlimont
et al. /Materials
Science
and Engineering
A226-228
(1997)
900-904
Table 1 Phase symbols, compositions and structures (Pearson symbol) Symbol
u
8
?
E
i
Y
Composition Structure
Al(-Cr,Ni) cF4
AWr7 mC104
Ah ?A mP48
Al&r mP180
icosahedral
AI&r, cI52
Symbol
IC
3,
Zl
3
a
J
Composition Structure
Al,Ni oP16
Al,Ni, hP5
Al,Fe,Ni, --x mP22
A&Fe mC102
amorphous
A&Fe, oC16
ti + K, Fig. 2(d), these phases are present according to X-ray diffraction. At A183,5Nii6.5 (5) primary dendritic solidification of IC appears to be superseded by subsequent cooperative IC+ 0: anomalous eutectic growth in a similar microstructural dispersion as at 15 at.% Ni. In the Al,,Ni,, (6) alloy primary rosette-like crystallization of IC is followed by cooperative growth of K + /z in the interstices. 3.3. Al- CT-- Ni In the Al,,,,Ni,,,Cr,,, (24) alloy the chill side of the foil shows areas which remain structureless upon etching: they are amorphous according to X-ray diffraction results. The major fraction of the cross-sectional area exhibits a with fine and uniformly distributed IC precipitates, Fig. 2(e). The solidification structure of 4&.7Cr17.3 (25) IS ’ d ominated by rapidly and freely grown 0 as is the case in the binary alloy with 15 at.% Cr, However, IC, il and amorphous structures are also Table 2 Aluminium alloys investigated and phases present Alloy No.
Alloying components at.% Ni
2 3 5 6 7 8 9 10 11 16 17 18 19 21 22 23 24 25
4.9 10.3 15.3 16.5 25.0 5.2 11.1 10.2 5.1 14.0 10.2 5.2 15.3 7.3 7.7
26
17.6
4
Fe 5.8 1.8 5.3 10.4 2.4 10.0 15.1 5.1 -
Phases
Cr 4.9 9.9 14.8 25.1 7.1 17.3 7.3
6 7c,fl a, 7GTl u, 7c u, IC ic,3, u, e U, e e .Q,y u, 7, ~,rr %Xl u, T, u, z, ff, z* u, 71,3 u, 7, a, I<,a, 0 K, I~,8, a
K, L, a
present. The Al,,,,Ni,,,$r,., (26) alloy shows predominantly nodular primary solidification structure which appears to consist of 7~+ 3,. Moreover, a featureless constituent appears to be amorphous according to Xray diffraction results. 3.4. Al-Ni-Fe In Al,,Ni,,ZFe,,, (11) the chill side shows some light etching crystals which may represent supersaturated a. The main microstructure consists of an anomalous u + zr eutectic. Following Fe-rich compositions first, in regular, feather-like JJ~A%Fel~.4 (18) remarkably dendrites of zr, often extending through the entire cross-section of the foil, are dominating the microstructure, Fig. 2(f). The remainder shows anomalous CI+ 21. The Al,,,,Ni,,Fe,,., (22) microstructure is dominated by primary dendritic 9 (A&Fe) with CI+ z1 eutectic (34 ma.%) which is partly lamellar, partly anomalous. On the Ni-rich side Al,,,,Ni,,.,Fe,., (16) exhibits extended dendrites of primary zl, the remainder is an anomalous eutectic. In A184,5Ni1,,2Fe5.3 (17) the primary feather-like rr is dominating again, CI+ zi eutectic fills the interstices, Fig. 2(h). The microstructure of Fe,,,GNi,,,Fe,,, (19) is practically identical. Alloy A179,8Ni,,,,Fe,, (21) is at the border of the high temperature homogeneity range of r1 and consists of a rather coarse grained, almost homogeneous microstructure of r1 accordingly (95 ma.%); the same is true for alloy A179.6Ni,,,,Fe,., (23). 4. Discussion The results show that phase dispersions on a considerably finer scale than in conventional Raney nickel precursor alloys can be obtained by rapid solidification and that the promoting components Cr and Fe can be kept in supersaturated solid solution over a significant range of compositions. First results for a hydrogenation reaction show, that non-optimized rapidly quenched Raney catalysts
are equivalent
tional optimized
catalysts.
in reactivity
to conven-
H.
Warlimont
et al. /Materials
Science
and Engineering
AZ%-228
(1997)
900-904
C
c
0.855 0
I 0.5
1
1.5
2
2.5
Fe/Ni ratio, (1- x)/x Fig. 3. Lattice parameters of the q phase Ai,(&Fe, solidified ribbons.
d
e
&
_ X)2 in rapidly
the ribbons where the cooling rate is highest. A very high growth rate v of the z1 phase can be derived from the long dendrite arms and columnar crystals extending all across the ribbons, alloys 17-19, Fig. 2(f)-(h). A lower bound can be estimated to be v 2 40 mm s-l. This is associated with an unusually large metastable extension of the homogeneity range of an intermetallic compound by rapid solidification as shown in terms of lattice parameter measurements on z1 at different alloy compositions in Fig. 3. Further accounts of this work will cover extended structural and volume fraction data, DSC and microstructural analyses.
References PI E. Rose&Laclau, M. Durand-Charre and J.-C. Joud, Res., 10 (1995)
PI D. Djaouadi and M. Besson,
h
Fig. 2. Nicrostructure of the cross section of rapidly solidified dhns. la) -%~,~Cr~.9 (7), (b) A1gO,lCrg.g W 14 &,&r,,,, (91, (4 &d%.~ (4), (9 ALd%Cr7.~ (24), (0 Gd%Pe~~.~ (1% (8) &3.6NM%.4 U% 00 ~s4.s%.2Fes.3 (17).
Gem.
Ind.,
62 (1995)
423.
[31 S. Hamar-Thibault, J. Gros, J.C. Joud, J. Masson, J.P. Damon and J.M. Bonnier, Stud. Surf. Sci. Catal. Y, (Preparation of Catalysts) (1991) 601. c41 J.M. Bonnier, J.P. Damon and J. Masson, Appl. Catal., 42 (1988) 285. [51 J.M. Bonnier, J.P. Damon, B. Delmon, B. Doumain and J. Masson, J. Chem. Phys., 84 (1987) 889. WI S. Hamar-Thibault, J. Masson, P. Fouilloux and J. Court, Appl. Cutal. A, 99 (1993) 131. t71 J. Gros, S. Hamar-Thibault and J.C. Joud, J. Mater. Sci., 24 (1989)
Quasicrystalline phases which are known to occur in rapidly quenched AI-Cr [12,14] and Al-Ni-Fe [15] alloys in the range of present interest could not be identified by X-ray diffraction but may be supposed to occur in a small volume fraction near the chill side of
J. Mater.
1154.
2987.
PI J.M. Bonnier, 5. Court, P.T. Wierzchowski Thibault, Appl. PI P. Furrer and UOI H. Warlimont, (1976) 101. 1111P. Furrer and
and S. Hamar-
Catal.,
53 (1989) 217. Warlimont, 2. Metallkde,
H. 62 (1971) 12; 100. W. Zingg and P. Furrer, Mater. Sci. Eng., 23 H. Warlimont,
Uazer. Sci. l&g.,
28
(1977) 127.
904
H. Warlimont
et al. /Materials
Science
[12] G.I. Rosen And D. Shechtman, Acta MetalI. Mater., 4.2 (1993) 177. [13] P. Budberg and A. Prince, in G. Petzow and G. Effenberg (eds.), Ternary aZZoys, Vol. 5 VCH, Weinheim, Basel, New York, 1992.
and Engilzeering
A226-228
(1997)
900-904
[14] D. Shechtman, I. Blech, D. Gratias and J.W. Cahn, PIys. Rev. Len., 53 (1984) 1951. [15] A.-P. Tsai, A. Inoue and T. Masumoto, Mater. Tram. JIM, 30 (1989) 150.