A continuum approach for modeling gravitational effects on grain settling and shape distortion during liquid phase sintering of tungsten heavy alloys

This paper presents a numerical approach for modeling gravity-induced grain settling and shape distortion during liquid phase sintering of tungsten heavy alloys. Using the framework of the continuum theory of sintering, this formulation provides insight into the development of microstructure heterogeneities during sintering by including grain settling. The model contains information about the properties of the solid and liquid constituents to describe both low-temperature and high-temperature sintering. The kinetic equations for porosity and solid volume fraction are based on mass conservation. To demonstrate the capabilities of the constitutive formulation, finite element analysis is used to simulate densification, shape distortion and solid liquid separation. The results are compared to data of liquid-phase sintering of cylindrical W-Ni-Fe samples. The developed model attempts to analyze the solid-skeletal dissolution and microstructure gradients that impact the system rigidity during liquid phase sintering. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.