A study of the Al-Pd-Pt alloy system

The constitution of the Al-Pd-Pt alloy system was studied above 35 at.% Al at 700, 780, 900 and 1100 C. The experiments revealed the formation of wide extensions of the binary Al-Pd and Al-Pt phases but no ternary phases. Continuous regions are probably formed between the isostructural phases Al ₄TM, Al₂₁TM₈, high-temperature AlTM, low-temperature AlTM and Al₃TM₅ (TM = Pd or Pt). The continuity between the Al₃TM₂ phases was revealed at 900 C, while at 1100 C the regions mutually extended from Al₃Ni ₂ and Al₃Pd₂ are separated by the ternary extension of Al₂Pt. The latter phase was found to dissolve up to 24 at.% Pd, which resulted in a sharp decrease of its Al concentration. The Al-Pd ε-phase was found to extend up to 18 at.% Pt at practically constant Al, while the Al-Pt ξ-phase was found to extend up to 7 at.% Pd.