Gravity and configurational energy induced microstructural changes in liquid phase sintering

Abstract

Liquid phase sintered materials consist of interconnected crystalline grains in a homogeneous matrix phase that forms the liquid at high temperatures. The dihedral angle, grain size, and volume fraction of solid determine the energy of the system. Energy minimization is possible by the separation of phases due to density differences. This explains why some materials exhibit settling or distortion due to gravity during liquid phase sintering. Experiments performed with W-Ni-Fe heavy alloys are used to measure the microstructural changesvs position that occur in liquid phase sintering under normal gravity. The experimentally observed segregation is less than the calculated equilibrium seg-regation due to the retarding effect from the rigid solid skeleton formed during sintering. These re-sults improve our understanding of microstructure, mechanical properties, component shape, and dimensional stability benefits that may be realized from low gravity sintering.