Phase equilibria of the Ni–Si–P system at 800°C

Abstract

Abstract The phase equilibria in the Ni–Si–P ternary system at 800 °C were experimentally investigated using optical microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction on 34 equilibrated alloys. Twenty-three-phase equilibria were well determined at 800 °C for the phosphorous content range of up to 75 at.%. The solubilities of P in Ni 3 Si, Ni 5 Si 2 , LT-Ni 2 Si, Ni 3 Si 2 , NiSi 2 and Ni 3 Si 2 , and those of Si in Ni 3 P, Ni 2 P or NiP 2 does not exceed 5 at.%. The solid solubility of Ni in SiP is too small to observe. The maximum solid solubility of P in NiSi is 17.5 at.%. On the other side of the system the solubility of Si in LT-Ni 5 P 2 , LT-Ni 12 P 5 , Ni 5 P 4 and NiP 3 were measured to be 15.1 at.%, 9.4 at.%, 8.7 at.% and 5.9 at.%, respectively. The obtained phase diagrams presents nine ternary intermetallic compounds (IMCs), including three new ternary phases τ 1 , τ 2 and τ 3 .