Variables on the precipitation of an intermetallic phase for liquid phase sintered W–Mo–Ni–Fe heavy alloys

Abstract

The concentration of Mo in the liquid phase of W–Mo–Ni–Fe heavy alloys during isothermal hold dictates the precipitation of an intermetallic phase during cooling. If the concentration of Mo atoms in the matrix phase exceeds an equilibrium value (between 8 and 9 at.%), Mo atoms have a strong tendency to precipitate along with W, Ni and Fe from the matrix phase onto the solid matrix phase interface during cooling. The coprecipitation of W, Mo, Ni, and Fe results in the formation of an intermetallic phase in the interface between the solid grains and the matrix phase, (W 4Mo 6)(Ni 7Fe 3), which possibly has the same structure as MoNi. This intermetallic phase is difficult to eliminate by a fast water-quench practice.