A STUDY OF THE Al–Ni–Pt ALLOY SYSTEM.
PHASE EQUILIBRIA AT 1100 AND 1300 °C

Abstract

The Al–Ni–Pt phase diagram studied in the whole compositional region at 1300 and 1100 °C. The Al₂Pt phase found to extend up to at least Al₅₃Ni₂₃Pt₂₄ composition, separating the Al₃Pt₂ and Al₃Ni₂ phase fields. The Al–Ni β phase dissolves up to 38 at.% Pt at 1100 °C, while at 1300 °C the β region probably extends between the isostructural CsCl-type phases forming at the Al–Pt and Al–Ni terminals. The AlNi₃ phase (γ’) extends up to 35 at.% Pt at practically constant Al concentration, while the high-temperature AlPt₃ extends up to 15 at.% Ni. A ternary phase is formed in a wide compositional region between the regions of γ, γ’, β, and AlNi₃. Apart from the AuCu-type structure of this ternary phase earlier reported, also its C-centered orthorhombic superstructure with a four-times larger unit cell revealed in the high-Al part of the compositional region.