Grain growth in liquid-phase-sintered W-Mo-Ni-Fe alloys

Abstract

Previous observations have shown smaller grain sizes and higher strengths in W-Ni-Fe heavy alloys containing molybdenum. This study focuses on the microstructure and grain growth kinetics for the W-Mo-Ni-Fe system processed at 1500 °C. The initial rate of grain growth follows an approximate square root time dependence in contrast to the cube root dependence typical for W-Ni-Fe alloys. Microprobe measurements show that chemical gradients are present in the solid grains, with high molybdenum content cores. The retarded grain growth from molybdenum additions is the result of a decreased tungsten solubility in the liquid during the early stages of sintering.