Kinetics of shrinkage and shape evolution during liquid phase sintering of tungsten heavy alloy

Abstract

A numerical model describing gravity-induced shape distortion and densification during solid and liquid phase sintering is proposed. The constitutive formulation is based on the continuum theory of sintering and implemented in commercial finite element software. Simulations under gravity-induced stress are attempted on the basis of the model parameters where viscosity is assumed to be temperature and porosity dependent. Viscosity is assessed through shrinkage and shrinkage rate data obtained experimentally from dilatometry over a controlled temperature regime. Effects of temperature, heating rate, and liquid phase formation on porosity evolution are analyzed. Additionally, sample studies on the influence of heating rate, gravity, friction coefficient, aspect ratio, and volume on the predicted distortion profiles after sintering of a tungsten heavy alloy are also presented. These numerical results are compared with experimental data from the literature.