Densification, microstructure and mechanical properties of Ta₄HfC₅-based ceramics obtained from synthesized nanoscale powder

Solvothermal treatment was used to synthesize nanoscale 4TaC-HfC (Ta₄HfC₅) powder at a relatively low calcination temperature and in a short period (1400 °C, 2 h). The obtained powder had uniform size distribution and dispersion. Ta₄HfC₅ ceramics were then consolidated via spark plasma sintering at 2100 °C. Ceramics had a better densification and smaller mean grain size at a shorter sintering time compared with that of materials sintered using mechanical ball milling method. The densification behavior of ceramics deriving from synthesized or ball milled powders was analyzed and the mechanical properties of different samples were investigated. To further increase the mechanical properties, a nearly fully dense Ta₄HfC₅-MoSi₂ ceramic was sintered using the synthesized powder. The mechanical properties of the ceramic composite doubled the strength values. This processing route demonstrated to be a viable approach to synthesize nanoscale Ta₄HfC₅ powder with high purity and uniformity, and obtain higher performances ceramics once sintered.