The influence of ingredient and preparation process on the microstructure of TZC molybdenum alloy

Different sintering and hot-pressing processes are employed to prepare the TZC alloy with two doping methods of TiH2/ZrH2 and TiC/ZrC addition, respectively. The evolution of the microstructure and composition distribution of the alloy under different processing conditions was studied through optical metallographic observation, scanning electron microscopy analysis and phase analysis. The results show that the phase constituents of the two doping methods are basically the same, but in comparison with that for the alloy with TiH2/ZrH2 addition, the density for the alloy with TiC/ZrC addition after sintering increases from 9.21 g·cm-3 to 9.68 g·cm-3, and the hardness increases from 210 HV to 245HV, respectively. Hot pressing after sintering significantly increases the density and hardness of the alloy, and the grain distribution changes from a bimodal distribution in the sintered state to a unimodal distribution. It is found that the phase structures of the two kinds of additives undergo transformation during high-temperature sintering, of which determines the reaction diffusion process, thereby affects the changes in density and hardness. The alloy with TiH2/ZrH2 addition forms different characteristic regions in the microstructure after hot pressing. Fine-grained, dense, and high-hardness TZC alloy can be directly obtained by hot-pressing the alloy with TiC/ZrC addition.