Effect of ultra-high temperature heat treatment on microstructures of W/ZrC cermets fabricated by different routes

Abstract:

W/ZrC cermets were fabricated by Displacive Compensation of Porosity (DCP) and Hot Pressing (HP), and then they were heat treated at 2600°C for 1 h. Microstructure changes of W/ZrC cermets before and after heat treatment were investigated. Results showed that both of two W/ZrC cermets had an increase of open porosity, a linear expansion and a weight loss after the heat treatment. Annealed DCP-derived W/ZrC cermets were still composed of dispersive W phases and continuous ZrC phases, but residual WC, W2C and Zr-Cu alloy were gone, instead, a large increase of pores and a sharp reduction of W phases appearing. While a new phase of W2C was formed in annealed HP-derived W/ZrC cermets, and W grains had a tendency to congregate together to form a big agglomerate phase.