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Phase equilibria in the Al-rich region of the Al–Ni–Re alloy system
Journal of Alloys and Compounds 479 (2009) L59–L61
Contents lists available at ScienceDirect
Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom
Letter
Phase equilibria in the Al-rich region of the Al–Ni–Re alloy system B. Grushko a,∗ , W. Kowalski b , S. Balanetskyy a,c a
Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany Institute of Materials Science, University of Silesia, 40007 Katowice, Poland c I.N. Frantsevich Institute for Problems of Materials Science, 03680 Kiev 142, Ukraine b
a r t i c l e
i n f o
Article history: Received 8 January 2009 Received in revised form 13 January 2009 Accepted 20 January 2009 Available online 6 February 2009 Keywords: Al–Ni–Re Phase equilibrium Powder X-ray diffraction SEM/EDX
a b s t r a c t Partial isothermal sections at 700, 800, 870 and 1030 ◦ C are presented for the Al–Al3 Ni2 –Al4 Re compositional range. The maximal solubility of Ni in the Al11 Re4 phase was found to be ∼6 at.%, in h-Al4 Re ∼4.5 at.% and in l-Al4 Re at least 1.5 at.%, in Al12 Re and Al6 Re around 1.0 at.%, while the solubility of Re in Al3 Ni and Al3 Ni2 was below 0.5 at.%. The only ternary orthorhombic phase is formed in a small compositional range around Al73.5 Ni18.5 Re8 . © 2009 Elsevier B.V. All rights reserved.
1. Introduction An investigation of the Al–Ni–Re phase diagram, which had been carried out in [1] on a series of solidified samples, did not reveal any ternary phase in the whole compositional range. According to this study, also solubility of the third element in all binary phases was low: in Al3 Re and Al6 Re up to ∼5 at.% Ni, in AlRe2 up to 2 at.% Ni and in AlNi up to ∼2 at.% Re. The AlNi3 , Al3 Ni2 , Al3 Ni, Al2 Re3 and Al4 Re phases exhibited negligible ternary extensions, and Al12 Re was not observed. In [2] this alloy system was studied at 1050–1150 ◦ C and Al concentrations below the tie-line corresponding to the Al3 Re–Al3 Ni2 equilibrium established in this study. No ternary phases were observed. At 1050 ◦ C the Al3 Re phase was found to contain up to 6.2 at.% Ni. The findings in [1], where also the high-Al range was studied, are in contrast to the complex constitution of the high-Al range of the Al–Pd–Re alloy system (Ni and Pd belong to the same column of the periodic table). In the latter, the ternary icosahedral and decagonal quasi-crystalline phases and a complex hexagonal phase were revealed ([3] and references therein). More recent investigation of Al–Ni–Re alloys in [4] demonstrated the existence of a ternary Al73.5 Ni18.5 Re8 phase structurally similar to the ternary Xphase forming in Al–Ni–Mo [5]. Apart from this, investigation of the binary Al–Re alloy system [6] revealed the existence of a hightemperature Al3 Re phase forming close to the Al11 Re4 phase, while
∗ Corresponding author. Tel.: +49 2461 612399; fax: +49 2461 616444. E-mail address: [email protected] (B. Grushko). 0925-8388/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2009.01.084
in [1,2] these phases were not discriminated. Therefore, a refinement of the Al–Ni–Re phase diagram is required. In this contribution we report the phase equilibria in the Al–Al3 Ni2 –Al4 Re compositional range at 700–1030 ◦ C. Our analysis is based on the amended Al–Re phase diagram [6] and the Al–Ni phase diagram from Ref. [7]. 2. Experimental The alloys were produced by levitation induction melting in a water-cooled copper crucible under a pure Ar atmosphere. The purity of Al was 99.999%, of Ni 99.98% and of Re 99.95%. The ingot weights were typically ∼5 g. Since Re dissolved only slowly in the alloys, they were re-melted several times in order to improve homogeneity. Parts of the ingots were studied in the as-cast and thermally annealed states. Annealing at 1030 ◦ C was applied for up to 140 h, at 870 ◦ C for up to 210 h, at 800 ◦ C for 1313 h and two samples were annealed at 700 ◦ C for 306 h. The alloys were examined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and transmission electron microscopy (TEM). The local phase compositions were determined in SEM by energy-dispersive X-ray analysis (EDX) on polished unetched cross-sections. Powder XRD was carried out in the transmission mode using Cu K␣1 radiation and an image plate detector. For TEM examinations powdered materials were dispersed on grids with carbon film. DTA was carried out in alumina crucibles at heating and cooling rates of 20 K/min.
3. Results A section between the congruent cubic AlNi and triclinic Al11 Re4 phases naturally separates the high-Al range. However, due to the high-melting temperatures of these phases (over 1600 ◦ C) and difficulties in homogenizing and equilibrating alloys, the reliably studied compositional range was even smaller: inside ∼Al–Al3 Ni2 –Al4 Re. Several samples were also prepared outside this range. Their investigation revealed a lack of equilibrium.
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B. Grushko et al. / Journal of Alloys and Compounds 479 (2009) L59–L61
Table 1 Crystal structures of the Al–Ni–Re compounds mentioned in the text and figures. Phase
Space group
Periods, nm
Al12 Re
Im3¯
Angles
a = 0.75200
–
Al6 Re
Cmcm
a = 0.76029, b = 0.66052, c = 0.90311
–
l-Al4 Re (Al33−x Re8 )
P 1¯
a = 0.51487, b = 0.90659, c = 1.3711
˛ = 96.851◦ , ˇ = 95.447◦ , = 92.450◦
h-Al4 Re
Cm
a = 0.51538, b = 1.7410, c = 0.51546
ˇ = 100.548◦
Al11 Re4
P 1¯
a = 0.51686, b = 0.89829, c = 0.51872
˛ = 90.541◦ , ˇ = 99.679◦ , = 105.159◦
Al3 Ni
Pnma
a = 0.66132, b = 0.73669, c = 0.48128
–
␦ (Al3 Ni2 )
¯ P 3m1
a = 0.404–0.405, c = 0.490–0.492
–
X (Al73.5 Ni18.5 Re8 )
Pbm2 or Pb21 m or Pbmm
a = 1.0048, b = 1.5423, c = 0.8367
–
Inside the investigated compositional range Al–Ni contains the well-known trigonal Al3 Ni2 and orthorhombic Al3 Ni phases [7], while Al–Re contains high-temperature h-Al4 Re and low-temperature l-Al4 Re phases, Al6 Re and Al12 Re [6]. Their crystallographic data are given in Table 1. All these phases are formed by peritectic reactions. As the structures of the l-Al4 Re, Al6 Re and Al12 Re phases were reliably established in previous works, that of the h-Al4 Re phase was reported to be unclear (see [6,8] and references therein). In the frame of the present work the latter phase was found to be stabilized by Ni, which allowed us to quench it and investigate its structure. In was found to be indeed of the Al4 W-type as was already assumed in [8] (see [9] for more detail). Although in Al–Re this structure transforms even by quenching from elevated temperatures [6,8], it can be reliably preserved up to room temperature in alloys containing >2 at.% Ni. The powder XRD patterns of the l-Al4 Re and h-Al4 Re phases are shown in Fig. 1a and b, respectively. The solubility of Re in Al3 Ni2 was found to be less than 0.5 at.% and in Al3 Ni close to zero. The maximal solubility of Ni in the
Al11 Re4 phase was found to be ∼6 at.%,1 in h-Al4 Re ∼4.5 at.% and in l-Al4 Re at least 1.5 at.%, while in Al6 Re and Al12 Re it was around 1.0 at.%. In Al–Re the h-Al4 Re phase transforms by cooling to Al11 Re4 and l-Al4 Re at 833 ◦ C [6], but its lower temperatures of existence decrease with increasing Ni concentration, therefore it was also revealed in our 800 ◦ C isothermal section (see below). The addition of Ni decreased the Al concentration of the h-Al4 Re and Al11 Re4 phases. The ternary Al73.5 Ni18.5 Re8 X-phase reported in [4] (see its typical powder XRD in Fig. 1c and the crystallographic data in Table 1) melts incongruently, the onset of melting was observed by DTA at 888 ◦ C. The X-phase was not observed in our as-cast samples. Considering the transformation temperatures of the abovementioned phases and in order to cover a reasonable part of the Al–Ni–Re phase diagram, we selected the temperatures of 1030, 870, 800 and 700 ◦ C for the determination of phase equilibria in the system. A partial 1030 ◦ C isothermal section of Al–Ni–Re is shown in Fig. 2a. This temperature is above the melting point of the Xphase. The corresponding composition belongs to the h-Al4 Re–␦–L three-phase compositional range. Also l-Al4 Re is molten at this temperature and a wide range adjacent to the Al–Re terminal belongs to the h-Al4 Re–L two-phase region. The liquid contained only a little Re. The solubility of Re in ␦ was below 0.5 at.%. The h-Al4 Re phase contained up to ∼4.5 at.% Ni. Fig. 2b shows a partial 870 ◦ C isothermal section of Al–Ni–Re. It already includes the ternary X-phase, which is in equilibrium with the ternary extension of h-Al4 Re, ␦ and the liquid. The l-Al4 Re phase extended up to at least 1.5 at.% Ni. Coexistence of the h-Al4 Re and l-Al4 Re phases was not detected metallographically. However, powder XRD revealed the h-Al4 Re structure in a sample where the grains of the solid phase in equilibrium with the liquid contained ∼2.5 at.% Ni, while this was the l-Al4 Re structure of the grains containing ∼1.5 at.% Ni. Subsequently, the three-phase equilibrium between the liquid and the ternary extensions of these phases is shown conditionally. At 800 ◦ C (Fig. 2c) the Al3 Ni phase is in equilibrium with h-Al4 Re. This results in the formation of three-phase regions: X–Al3 Ni–␦, hAl4 Re–Al3 Ni–X and h-Al4 Re–Al3 Ni–L in addition to h-Al4 Re–␦–X. The equilibrium between the liquid and the ternary extensions of the l-Al4 Re phase is close to the Al–Re terminal, leaving only a narrow strip (not studied) for expected equilibrium between Al6 Re, l-Al4 Re and the liquid. Accordingly, the solubility of Ni in Al6 Re should be very low at this temperature.
Fig. 1. Powder XRD patterns (Cu K␣1 rad.) of the: (a) l-Al4 Re phase of Al78 Ni1.5 Re20.5 , (b) h-Al4 Re phase of Al77 Ni2.5 Re20.5 , and (c) X-phase of Al73.5 Ni18.5 Re8 . In (a) the sample contained (Al), whose reflections are marked by arrows.
1 This result is in agreement with that in [2], although there the Al3 Re phase and not Al11 Re4 is mentioned. These phases of close compositions are not discriminated in [2]. Our powder XRD examinations confirmed the Al11 Re4 structure.
B. Grushko et al. / Journal of Alloys and Compounds 479 (2009) L59–L61
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Fig. 2. Partial isothermal sections of the Al–Ni–Re phase diagram at: (a) 1030 ◦ C, (b) 870 ◦ C, (c) 800 ◦ C, and (d) 700 ◦ C. Provisional lines are shown by broken lines. The alloy compositions are marked by squares. L is the liquid. The ranges where the equilibria were not clarified are marked by ‘?’.
At 700 ◦ C only two samples were studied. One defined the equilibrium between Al6 Re, Al12 Re and Al3 Ni, and the other the equilibrium between Al12 Re, Al3 Ni and the liquid (see Fig. 2d) The Ni solubility in the Al6 Re, Al12 Re phases was around 1 at.%. As mentioned above, a structure similar to that of the Al–Ni–Re X-phase was observed in the Al–Ni–Mo alloy system [5]. There it is formed in a small compositional range around Al75.1 Ni14.2 Mo10.7 and can be in equilibrium with Al4 Mo, which is isostructural to h-Al4 Re. On the other hand, the ternary N-phase, also existing in the Al–Ni–Mo alloy system [5], was not observed in the relevant compositional range of the Al–Ni–Re. The general structure of the high-Al part of the Al–Ni–Re phase diagram is also very different from that of the Al–Ni–Mn alloy system (Mn and Re belong to the same column of the periodic table, while Mo belongs to the neighboring column) containing a number of other ternary phases in its high-Al compositional range [10].
Acknowledgements We thank V. Lenzen and M. Schmidt for technical contribution. WK thanks Forschungszentrum Jülich and the University of Silesia for financial support. References [1] L.A. Cornish, M.J. Witcomb, J. Alloys Compd. 291 (1999) 145. [2] Saito, K. Kurokawa, S. Hayashi, T. Takashima, T. Narita, J. Jpn. Inst. Met. 71 (2007) 793 (in Japanese). [3] S. Balanetskyy, B. Grushko, J. Alloys Compd. 456 (2008) 105. [4] B. Grushko, S. Balanetskyy, Powder Diffract. 23 (2008) 251. [5] B. Grushko, S. Mi, J. Highfield, J. Alloys Compd. 334 (2002) 187. [6] S. Balanetskyy, B. Grushko, J. Alloys Compd. 457 (2008) 348. [7] T.B. Massalski, H. Okamoto, P.R. Subramanian, L. Kacprzak, Binary Alloy Phase Diagrams, 2nd ed., ASM International, Metals Park, OH, 1990. [8] J.C. Schuster, L. Perring, K.W. Richter, H. Ipser, Y. Grin, F. Weitzer, J. Alloys Compd. 320 (2001) 224. [9] B. Grushko, Powder Diffract., in press, doi:10.1154/1.2957883. [10] S. Balanetskyy, unpublished report.
Contents lists available at ScienceDirect
Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom
Letter
Phase equilibria in the Al-rich region of the Al–Ni–Re alloy system B. Grushko a,∗ , W. Kowalski b , S. Balanetskyy a,c a
Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany Institute of Materials Science, University of Silesia, 40007 Katowice, Poland c I.N. Frantsevich Institute for Problems of Materials Science, 03680 Kiev 142, Ukraine b
a r t i c l e
i n f o
Article history: Received 8 January 2009 Received in revised form 13 January 2009 Accepted 20 January 2009 Available online 6 February 2009 Keywords: Al–Ni–Re Phase equilibrium Powder X-ray diffraction SEM/EDX
a b s t r a c t Partial isothermal sections at 700, 800, 870 and 1030 ◦ C are presented for the Al–Al3 Ni2 –Al4 Re compositional range. The maximal solubility of Ni in the Al11 Re4 phase was found to be ∼6 at.%, in h-Al4 Re ∼4.5 at.% and in l-Al4 Re at least 1.5 at.%, in Al12 Re and Al6 Re around 1.0 at.%, while the solubility of Re in Al3 Ni and Al3 Ni2 was below 0.5 at.%. The only ternary orthorhombic phase is formed in a small compositional range around Al73.5 Ni18.5 Re8 . © 2009 Elsevier B.V. All rights reserved.
1. Introduction An investigation of the Al–Ni–Re phase diagram, which had been carried out in [1] on a series of solidified samples, did not reveal any ternary phase in the whole compositional range. According to this study, also solubility of the third element in all binary phases was low: in Al3 Re and Al6 Re up to ∼5 at.% Ni, in AlRe2 up to 2 at.% Ni and in AlNi up to ∼2 at.% Re. The AlNi3 , Al3 Ni2 , Al3 Ni, Al2 Re3 and Al4 Re phases exhibited negligible ternary extensions, and Al12 Re was not observed. In [2] this alloy system was studied at 1050–1150 ◦ C and Al concentrations below the tie-line corresponding to the Al3 Re–Al3 Ni2 equilibrium established in this study. No ternary phases were observed. At 1050 ◦ C the Al3 Re phase was found to contain up to 6.2 at.% Ni. The findings in [1], where also the high-Al range was studied, are in contrast to the complex constitution of the high-Al range of the Al–Pd–Re alloy system (Ni and Pd belong to the same column of the periodic table). In the latter, the ternary icosahedral and decagonal quasi-crystalline phases and a complex hexagonal phase were revealed ([3] and references therein). More recent investigation of Al–Ni–Re alloys in [4] demonstrated the existence of a ternary Al73.5 Ni18.5 Re8 phase structurally similar to the ternary Xphase forming in Al–Ni–Mo [5]. Apart from this, investigation of the binary Al–Re alloy system [6] revealed the existence of a hightemperature Al3 Re phase forming close to the Al11 Re4 phase, while
∗ Corresponding author. Tel.: +49 2461 612399; fax: +49 2461 616444. E-mail address: [email protected] (B. Grushko). 0925-8388/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2009.01.084
in [1,2] these phases were not discriminated. Therefore, a refinement of the Al–Ni–Re phase diagram is required. In this contribution we report the phase equilibria in the Al–Al3 Ni2 –Al4 Re compositional range at 700–1030 ◦ C. Our analysis is based on the amended Al–Re phase diagram [6] and the Al–Ni phase diagram from Ref. [7]. 2. Experimental The alloys were produced by levitation induction melting in a water-cooled copper crucible under a pure Ar atmosphere. The purity of Al was 99.999%, of Ni 99.98% and of Re 99.95%. The ingot weights were typically ∼5 g. Since Re dissolved only slowly in the alloys, they were re-melted several times in order to improve homogeneity. Parts of the ingots were studied in the as-cast and thermally annealed states. Annealing at 1030 ◦ C was applied for up to 140 h, at 870 ◦ C for up to 210 h, at 800 ◦ C for 1313 h and two samples were annealed at 700 ◦ C for 306 h. The alloys were examined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and transmission electron microscopy (TEM). The local phase compositions were determined in SEM by energy-dispersive X-ray analysis (EDX) on polished unetched cross-sections. Powder XRD was carried out in the transmission mode using Cu K␣1 radiation and an image plate detector. For TEM examinations powdered materials were dispersed on grids with carbon film. DTA was carried out in alumina crucibles at heating and cooling rates of 20 K/min.
3. Results A section between the congruent cubic AlNi and triclinic Al11 Re4 phases naturally separates the high-Al range. However, due to the high-melting temperatures of these phases (over 1600 ◦ C) and difficulties in homogenizing and equilibrating alloys, the reliably studied compositional range was even smaller: inside ∼Al–Al3 Ni2 –Al4 Re. Several samples were also prepared outside this range. Their investigation revealed a lack of equilibrium.
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B. Grushko et al. / Journal of Alloys and Compounds 479 (2009) L59–L61
Table 1 Crystal structures of the Al–Ni–Re compounds mentioned in the text and figures. Phase
Space group
Periods, nm
Al12 Re
Im3¯
Angles
a = 0.75200
–
Al6 Re
Cmcm
a = 0.76029, b = 0.66052, c = 0.90311
–
l-Al4 Re (Al33−x Re8 )
P 1¯
a = 0.51487, b = 0.90659, c = 1.3711
˛ = 96.851◦ , ˇ = 95.447◦ , = 92.450◦
h-Al4 Re
Cm
a = 0.51538, b = 1.7410, c = 0.51546
ˇ = 100.548◦
Al11 Re4
P 1¯
a = 0.51686, b = 0.89829, c = 0.51872
˛ = 90.541◦ , ˇ = 99.679◦ , = 105.159◦
Al3 Ni
Pnma
a = 0.66132, b = 0.73669, c = 0.48128
–
␦ (Al3 Ni2 )
¯ P 3m1
a = 0.404–0.405, c = 0.490–0.492
–
X (Al73.5 Ni18.5 Re8 )
Pbm2 or Pb21 m or Pbmm
a = 1.0048, b = 1.5423, c = 0.8367
–
Inside the investigated compositional range Al–Ni contains the well-known trigonal Al3 Ni2 and orthorhombic Al3 Ni phases [7], while Al–Re contains high-temperature h-Al4 Re and low-temperature l-Al4 Re phases, Al6 Re and Al12 Re [6]. Their crystallographic data are given in Table 1. All these phases are formed by peritectic reactions. As the structures of the l-Al4 Re, Al6 Re and Al12 Re phases were reliably established in previous works, that of the h-Al4 Re phase was reported to be unclear (see [6,8] and references therein). In the frame of the present work the latter phase was found to be stabilized by Ni, which allowed us to quench it and investigate its structure. In was found to be indeed of the Al4 W-type as was already assumed in [8] (see [9] for more detail). Although in Al–Re this structure transforms even by quenching from elevated temperatures [6,8], it can be reliably preserved up to room temperature in alloys containing >2 at.% Ni. The powder XRD patterns of the l-Al4 Re and h-Al4 Re phases are shown in Fig. 1a and b, respectively. The solubility of Re in Al3 Ni2 was found to be less than 0.5 at.% and in Al3 Ni close to zero. The maximal solubility of Ni in the
Al11 Re4 phase was found to be ∼6 at.%,1 in h-Al4 Re ∼4.5 at.% and in l-Al4 Re at least 1.5 at.%, while in Al6 Re and Al12 Re it was around 1.0 at.%. In Al–Re the h-Al4 Re phase transforms by cooling to Al11 Re4 and l-Al4 Re at 833 ◦ C [6], but its lower temperatures of existence decrease with increasing Ni concentration, therefore it was also revealed in our 800 ◦ C isothermal section (see below). The addition of Ni decreased the Al concentration of the h-Al4 Re and Al11 Re4 phases. The ternary Al73.5 Ni18.5 Re8 X-phase reported in [4] (see its typical powder XRD in Fig. 1c and the crystallographic data in Table 1) melts incongruently, the onset of melting was observed by DTA at 888 ◦ C. The X-phase was not observed in our as-cast samples. Considering the transformation temperatures of the abovementioned phases and in order to cover a reasonable part of the Al–Ni–Re phase diagram, we selected the temperatures of 1030, 870, 800 and 700 ◦ C for the determination of phase equilibria in the system. A partial 1030 ◦ C isothermal section of Al–Ni–Re is shown in Fig. 2a. This temperature is above the melting point of the Xphase. The corresponding composition belongs to the h-Al4 Re–␦–L three-phase compositional range. Also l-Al4 Re is molten at this temperature and a wide range adjacent to the Al–Re terminal belongs to the h-Al4 Re–L two-phase region. The liquid contained only a little Re. The solubility of Re in ␦ was below 0.5 at.%. The h-Al4 Re phase contained up to ∼4.5 at.% Ni. Fig. 2b shows a partial 870 ◦ C isothermal section of Al–Ni–Re. It already includes the ternary X-phase, which is in equilibrium with the ternary extension of h-Al4 Re, ␦ and the liquid. The l-Al4 Re phase extended up to at least 1.5 at.% Ni. Coexistence of the h-Al4 Re and l-Al4 Re phases was not detected metallographically. However, powder XRD revealed the h-Al4 Re structure in a sample where the grains of the solid phase in equilibrium with the liquid contained ∼2.5 at.% Ni, while this was the l-Al4 Re structure of the grains containing ∼1.5 at.% Ni. Subsequently, the three-phase equilibrium between the liquid and the ternary extensions of these phases is shown conditionally. At 800 ◦ C (Fig. 2c) the Al3 Ni phase is in equilibrium with h-Al4 Re. This results in the formation of three-phase regions: X–Al3 Ni–␦, hAl4 Re–Al3 Ni–X and h-Al4 Re–Al3 Ni–L in addition to h-Al4 Re–␦–X. The equilibrium between the liquid and the ternary extensions of the l-Al4 Re phase is close to the Al–Re terminal, leaving only a narrow strip (not studied) for expected equilibrium between Al6 Re, l-Al4 Re and the liquid. Accordingly, the solubility of Ni in Al6 Re should be very low at this temperature.
Fig. 1. Powder XRD patterns (Cu K␣1 rad.) of the: (a) l-Al4 Re phase of Al78 Ni1.5 Re20.5 , (b) h-Al4 Re phase of Al77 Ni2.5 Re20.5 , and (c) X-phase of Al73.5 Ni18.5 Re8 . In (a) the sample contained (Al), whose reflections are marked by arrows.
1 This result is in agreement with that in [2], although there the Al3 Re phase and not Al11 Re4 is mentioned. These phases of close compositions are not discriminated in [2]. Our powder XRD examinations confirmed the Al11 Re4 structure.
B. Grushko et al. / Journal of Alloys and Compounds 479 (2009) L59–L61
L61
Fig. 2. Partial isothermal sections of the Al–Ni–Re phase diagram at: (a) 1030 ◦ C, (b) 870 ◦ C, (c) 800 ◦ C, and (d) 700 ◦ C. Provisional lines are shown by broken lines. The alloy compositions are marked by squares. L is the liquid. The ranges where the equilibria were not clarified are marked by ‘?’.
At 700 ◦ C only two samples were studied. One defined the equilibrium between Al6 Re, Al12 Re and Al3 Ni, and the other the equilibrium between Al12 Re, Al3 Ni and the liquid (see Fig. 2d) The Ni solubility in the Al6 Re, Al12 Re phases was around 1 at.%. As mentioned above, a structure similar to that of the Al–Ni–Re X-phase was observed in the Al–Ni–Mo alloy system [5]. There it is formed in a small compositional range around Al75.1 Ni14.2 Mo10.7 and can be in equilibrium with Al4 Mo, which is isostructural to h-Al4 Re. On the other hand, the ternary N-phase, also existing in the Al–Ni–Mo alloy system [5], was not observed in the relevant compositional range of the Al–Ni–Re. The general structure of the high-Al part of the Al–Ni–Re phase diagram is also very different from that of the Al–Ni–Mn alloy system (Mn and Re belong to the same column of the periodic table, while Mo belongs to the neighboring column) containing a number of other ternary phases in its high-Al compositional range [10].
Acknowledgements We thank V. Lenzen and M. Schmidt for technical contribution. WK thanks Forschungszentrum Jülich and the University of Silesia for financial support. References [1] L.A. Cornish, M.J. Witcomb, J. Alloys Compd. 291 (1999) 145. [2] Saito, K. Kurokawa, S. Hayashi, T. Takashima, T. Narita, J. Jpn. Inst. Met. 71 (2007) 793 (in Japanese). [3] S. Balanetskyy, B. Grushko, J. Alloys Compd. 456 (2008) 105. [4] B. Grushko, S. Balanetskyy, Powder Diffract. 23 (2008) 251. [5] B. Grushko, S. Mi, J. Highfield, J. Alloys Compd. 334 (2002) 187. [6] S. Balanetskyy, B. Grushko, J. Alloys Compd. 457 (2008) 348. [7] T.B. Massalski, H. Okamoto, P.R. Subramanian, L. Kacprzak, Binary Alloy Phase Diagrams, 2nd ed., ASM International, Metals Park, OH, 1990. [8] J.C. Schuster, L. Perring, K.W. Richter, H. Ipser, Y. Grin, F. Weitzer, J. Alloys Compd. 320 (2001) 224. [9] B. Grushko, Powder Diffract., in press, doi:10.1154/1.2957883. [10] S. Balanetskyy, unpublished report.