High temperature plastic flow in TiC-20wt.%Mo2C-20wt.%Ni cermet

High temperature plastic flow in TiC-20wt.%Mo2C-20wt.%Ni with a carbide grain size of 1.93 μm is examined at temperatures between 1100 and 1225 °C in compression testing. The flow stress is largely dependent on temperature and strain rate. The log-log plot of stress vs. strain rate is represented by a sigmoidal relationship and is divided into three regions at a constant temperature. The strain rate sensitivity exponent takes the highest value of about 0.6 in the intermediate strain rate region. The stress-strain rate relationship is similar to that in superplastic metals. The rate-controlling mechanism is considered to be the sliding along the carbide-carbide boundaries in the intermediate strain rate region and the dislocation climb in carbide grains in the high strain rate region. The transition from the low to intermediate strain rate region is also discussed.