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Phase Diagram Evaluations: Section II

Al-Ce-Cu (Aluminum-Cerium-Copper) V. Raghavan

The early experimental data on this system were reviewed/updated by [2004Ria] and [2007Rag]. Subsequently, the phase relationships in the Al-rich region were studied by [2007Bel] and reviewed by [2008Rag]. Recently, the phase equilibria in a wider range of composition were reported by [2009Yao] and assessed thermodynamically by [2009Bo].

e1(bcc), e2 (B82, Ni2In-type hexagonal), Cu3Al2 (d, rhombohedral), Cu9Al4(HT) (c0, D82, Cu5Zn8-type cubic), Cu9Al4(LT) (c1, D83-type cubic), and Cu3Al (b, bcc). In the above, HT = high-temperature and LT = lowtemperature. The Ce-Cu phase diagram [Massaslki2] has the following intermediate phases: Cu6Ce (orthorhombic, space group Pnma), Cu5Ce (D2d, CaCu5-type hexagonal), Cu4Ce (orthorhombic, space group Pnnm), Cu2Ce (orthorhombic, space group Imma), and CuCe (B27, FeB-type orthorhombic).

Binary Systems The Al-Ce phase diagram was reassessed thermodynamically by [2005Gao], using new experimental results as additional input. The intermediate phases in this system are: aCe3Al (D019, Ni3Sn-type hexagonal), bCe3Al (L12, AuCu3-type cubic), Ce2Al (stable between 775 and 648 C; Co2Si-type orthorhombic?), CeAl (orthorhombic), CeAl2 (C15, MgCu2-type cubic), aCeAl3 (Ni3Sn-type hexagonal), bCeAl3 (stable between 1192 and 973 C), CeAl4 or bCe3Al11 (D13, Al4Ba-type tetragonal), and aCe3Al11 (aLa3Al11-type orthorhombic). The Al-Cu phase diagram [1998Liu] depicts a number of intermediate phases: CuAl2 (h, C16-type tetragonal), CuAl (g1, orthorhombic), CuAl (g2, monoclinic), Cu5Al4(LT) (f2, orthorhombic),

Table 1

Ternary Compounds Five ternary compounds known in this system were summarized by [2004Ria] and [2009Yao] (see Table 1). Al12 xCuxCe (s1) (4.0 £ x £ 4.52) has ThMn12-type tetragonal structure. Al17 xCuxCe2 (s2) (6.5 £ x £ 7.55) is Th2Zn17type rhombohedral. Al13 xCuxCe (s3) (6.62 £ x £ 6.92) is cubic with NaZn13 as the prototype. Al4 xCuxCe(s4) (0.74 £ x £ 1.10) is Al4Ba-type tetragonal. AlCuCe (s5) is Fe2P-type hexagonal. The designations s1, s2, etc. adopted here are those given by [2009Yao] and differ from those given by [2009Bo].

Al-Ce-Cu crystal structure and lattice parameter data [2009Yao]

Phase Al12 xCuxCe (s1) (4.0 £ x £ 4.52) Al17 xCuxCe2 (s2) (6.5 £ x £ 7.55) Al13 xCuxCe (s3) (6.62 £ x £ 6.92) Al4 xCuxCe (s4) (0.74 £ x £ 1.10) AlCuCe (s5)

AlCu2Ce2 (s¢)

Composition, at.% 61.5-57.5 Al 30.8-34.8 Cu 7.7 Ce 55.3-49.7 Al 34.2-39.7 Cu 10.5 Ce 45.6-43.4 Al 47.3-49.4Cu 7.1 Ce 65.2-58 Al 14.8-22 Cu 20 Ce 33.3 Al 33.3 Cu 33.3 Ce 20 Al 40Cu 40 Ce

Pearson symbol

Space group

Prototype

Lattice parameter, nm

tI26

I4/mmm

Mn12Th

a = 0.88223 c = 0.51557

hR57

R3m

Th2Zn17

a = 0.89501 c = 1.30452

cF112

Fm3c

NaZn13

a = 1.18754

tI10

I4/mmm

Al4Ba

a = 0.42633 c = 1.06852

hP9

P62m

Fe2P

a = 0.7176 c = 0.4201

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Journal of Phase Equilibria and Diffusion Vol. 31 No. 3 2010

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275

Section II: Phase Diagram Evaluations

Fig. 1 Al-Ce-Cu isothermal section at 230 C [2009Yao]. N