Elimination of Pores During Liquid Phase Sintering of Mo—Ni

Abstract

The elimination of isolated large pores during liquid phase sintering has been studied in a 96Mo–4Ni alloy (wt-%). The large pores have been produced at the site of spherical Ni particles upon their melting. The grain growth in the vicinity of large pores is directly observed using etch boundaries within the grains formed during a cyclic sintering treatment. Grains around the pores grow along the surface of the pores. Since no growth occurs towards the pore centres, all grains have a negative curvature towards the pore centres. When pores are filled up by liquid, the surrounding grains grow into the liquid pools by preferential precipitation of material on to grain surfaces with negative curvature. In addition, some grains are disintegrated from the grain skeleton and appear to move into the liquid pool. With these processes of grain growth and skeleton disintegration, the microstructural homogenization results in a typical dense liquid phase sintered microstructure. A liquid-grain mixture flow into the pores is also observed. PM/0293