The Al–Ni–Si phase diagram—Part III: Phase equilibria in the nickel rich part

Abstract

The ternary Al–Ni–Si phase diagram between 66.7 and 100 at.% Ni was investigated by a combination of differential thermal analysis (DTA), powder X-ray diffraction (XRD), metallography and electron probe microanalysis (EPMA). The ternary phase equilibria were analyzed within the isothermal section at 1000 °C, and DTA was used to determine the various invariant reactions within the three sections at 70, 75 and 80 at.% Ni. A liquidus surface projection was constructed for the entire composition range by combining our experimental data with those from literature. Powder XRD was used to determine the lattice parameters and their variation as a function of composition for the solid solutions. Based on our analysis, we report the existence of two major solid solution phases, namely, (a) the solid solution of Al and Si in Ni and (b) the complete solid solution between the isostructural binary compounds AlNi 3 (γ′) and Ni 3Si (β 1).