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 Al4TM, 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 Al3Ni2 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.