Synthesis of a Fine (Ta0.8,Hf0.2)C Powder from Carbide or Oxide Powder Mixtures

Tantalum hafnium carbide ((Ta0.8,Hf0.2)C) powders were successfully synthesized using a modified spark plasma sintering (SPS) apparatus with TaC/HfC or Ta2O5/HfO2/C starting materials. The (Ta0.8,Hf0.2)C obtained from the carbides had a finer particle size of 220 nm, whereas those obtained from the oxides had less contamination during the milling process (0.35 wt%) than the other case. Particle coarsening of the solid‐solution phase was effectively suppressed by using a modified SPS apparatus because of the fast heating/cooling rate. High‐energy ball milling promoted a solid‐solution reaction for the formation of (Ta0.8,Hf0.2)C by refining the size and inducing the homogeneous mixing of the starting materials. By the combination of the fast heating and high‐energy ball milling, fine tantalum hafnium carbide powders with low contamination were successfully synthesized.