Structural and phase equilibria investigations in the transition metal-rich part of the ternary system Ni-Pd-Al

Both microstructural and X-ray diffraction investigations were carried out on as-cast, heat treated (1000 degrees C) and liquid quenched Ni-Pd-Al allo ys containing aluminium up to 40 at.%. A liquidus projection surface was cr eated in the transition metal-rich part of the ternary system Ni-Pd-Al from investigations made on the as-cast alloys. A partial isothermal Ni-Pd-Al s ection at 1000 degrees C was drafted for the heat treated alloys with alumi nium content up to 40 at.%. Palladium is substituted for nickel in Ni3Al (C u3Au type) up to 12.2 at.% at 1000 degrees C. The solubility of Pd in Ni3Al can be extended metastably up to 17.5 at.% by means of liquid quenching. T he metastable ternary phase (Ni, Pd)(3)Al-2(m) (Pearson code tP4, space gro up P4/mmm, CuAu type) occurs in the composition range of 25 to 40 at.% Pd.