Effect of grain shape on abnormal grain growth in liquid-phase-sintered Nb1-xTxC-Co alloys

The effect of titanium substitution for niobium on the grain shape change, grain growth inhibition, and abnormal grain growth during liquid-phase sintering of Nb1-xTixC-Co alloy was studied. With increased titanium substitution, the shape of the Nb1-xTiC grains in the liquid cobalt matrix was changed from a cube with round corners to a cube with angular corners, which implied increased edge energy. As the grain corners became more angular, the grain growth became markedly inhibited, and abnormal grain growth occurred. The results could be best explained by the increased edge energy of the interface of the Nb1-xTiC grains, which increased the barrier for the growth by two-dimensional nucleation.