Finite element simulation of liquid phase sintering with tungsten heavy alloys

Abstract

Densification and distortion of W-Ni-Fe tungsten heavy alloys during liquid phase sintering are modeled using constitutive laws of grain growth, densification, and deformation. The models are "calibrated" via carefully designed experiments to obtain the necessary parameters to enable modeling. Metallographic analysis of quenched samples is used to obtain grain size data as functions of time and temperature, while dilatometry and dimensional analyses are used to determine the bulk viscosity and shear viscosity. The influences of gravity, substrate friction, surface tension, and solid content on distorted shapes are shown by comparing predictions from the finite element method with experimentally measured shapes. The finite element simulations accurately predict several phenomena, including increased distortion with longer sintering times and higher liquid contents, slumping due to gravity, spheroidization due to surface tension, and friction-related distortion due to sticking of the part to the substrate.