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Section II: Phase Diagram Evaluations

Al-Mg-Sc-Ti-Zr (Aluminum-Magnesium-ScandiumTitanium-Zirconium) V. Raghavan

A vertical section for this five-component system was determined by [1996Che] at 0.3Sc-0.15Ti-0.15Zr (mass%).

Lower Order Systems The Al-Mg phase diagram has the following intermediate phases: Mg2 Al3 (cubic, labeled b), R or e (rhombohedral), and Mg17 Al12 (A12, aMn-type cubic, denoted c). The Al-Sc phase diagram depicts the following intermediate compounds: ScAl3 (L12, AuCu3 -type cubic), ScAl2 (C15, MgCu2 -type cubic), ScAl (B2, CsCl-type cubic), and Sc2 Al (B82, Ni2 In-type hexagonal). The intermediate phases in the Al-Ti system are: Ti3 Al (D019, Ni3 Sn-type hexagonal, denoted as a2), TiAl (L10, AuCu-type tetragonal, denoted c), TiAl2 (HfGa2 -type tetragonal), TiAl3 (HT) (D022-type tetragonal), and TiAl3 (LT) (tetragonal). There are a number of intermediate phases in the Al-Zr system. The only phase of interest in the results on Al-rich alloys reviewed here is ZrAl3 (D023-type tetragonal). Updates of the Al-Mg-Sc and Al-Mg-Sc-Zr systems were presented by [2007Rag] and [2008Rag], respectively. Only binary compounds appear at the Al-rich corner in the reviewed phase equilibria of these systems.

Quaternary Vertical Section The experimental details used by [1996Che] are not given in their paper. The vertical section constructed by them at constant content of 0.3Sc-0.15Ti-0.15Zr (mass%) is redrawn in Fig. 1. Only binary compounds are present. On solidification, near the Al corner, the four-phase equilibrium of (Al) + Mg2Al3 + ScAl3 + (Ti,Zr)Al3 is seen.

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Fig. 1 Al-Mg-Sc-Ti-Zr vertical section at 0.3Sc-0.15Ti-0.15Zr (mass%) [1996Che]

References 1996Che: V.V. Cherkasov, P.P. Pobezhimov, L.P. Nefedova, E.V. Belov, and G.M. Kuznetsov, Special Features of the Structure Formation and Properties of Castable Al-Mg Alloys Alloyed with Scandium, Metallovedenie Term. Obrab. Metallov, 1996, (6), p 30-32, in Russian; TR: Metal Sci. Heat Treatment, 1996, (5-6), p 268-270 2007Rag: V. Raghavan, Al-Mg-Sc (Aluminum-MagnesiumScandium), J. Phase Equilb. Diffus., 2007, 28(5), p 471-472 2008Rag: V. Raghavan, Al-Mg-Sc-Zr (Aluminum-MagnesiumScandium-Zirconium), J. Phase Equilb. Diffus., 2008, 29(2), p 192-193

Journal of Phase Equilibria and Diffusion Vol. 30 No. 2 2009