A study of the high-Al part of the Al–Pd–Re phase diagram

Abstract

The Al–Pd–Re phase diagram was studied in the compositional range above 50 at.% Al at temperatures between 700 and 1100 °C. Apart from the Al–Pd ɛ-phases exhibiting ternary extension up to ∼6 at.% Re, the binary phases in both Al–Pd and Al–Re dissolve only a little of the third element. In addition to the stable ternary icosahedral and decagonal phases reported earlier a new ternary hexagonal χ-phase ( a ≈ 1.231, c ≈ 2.742 nm) was discovered in a compositional range from Al 77.8Pd 13.8Re 8.4 to Al 76.2Pd 19.0Re 4.8. The overall compositional range of the icosahedral phase was found to be between 8.3 and 10.4 at.% Re and between 68.5 and 71.9 at.% Al. This range shifts to lower Re at lower temperatures. Partial isothermal sections at 1100, 1000, 790 and 700 °C are presented.