Microstructure of Mo powders sintered with Ni and Ni3Al powders.

Abstract

When Ni or Ni3Al powders are added to Mo powders, sintering is greatly promoted to result in significantly higher densities even at lower temperatures than one-half of the homologous temperature for Mo. The activation energies obtained for mixed sintering are lower than that required for mutual volume diffusion between Mo and Ni.TEM observations of microstructure after sintering Mo and Ni powders at 1573 K revealed the formation of a MoNi phase at interfaces of Mo particles. When sintered at 1673 K, not only Mo-Ni phase is seen at the interface but also the Mo particle surface became slightly wavy as a result of contacting with the liquid Mo-Ni phase.When Mo powders were sintered with a 5 wt.% of Ni3Al alloy powders at 1573 K, the microstructure obtained by quenching from this temperature is a mixture of Mo and Ni3Al. But the microstructure obtained by furnace-cooling is a mixture of Mo, Mo-Ni and Ni3AI which is surrounded by MoNi3.