EFFECT OF COALESCENCE OF THE GRAIN COARSENING DURING LIQUID-PHASE SINTERING OF TaC-TiC-Ni CERMETS

摘要

During heat treatment of TaC-2TiC-30Ni(in wt/100)specimens at 1400 deg. C, abnormally large and faceted(Ta, Ti)C grains appeared. These abnormal grains usually coalesced with surrounding small grains and grain boundaries were formed between them. Inside the abnormally grown large grains, many small grains were entrapped. The observed abnormal grain growth(AGG)was explained in terms of a two- dimensional nucleation controlled growth mechanism. Coalescence was suggested to enhance the growth rate because re-entrant edges due to grain boundaries provide easier two-dimensional nucleation sites.