Preparation of TiB₂ powders by mechanical alloying

TiB₂ powders with submicrometer size were synthesized by mechanical alloying (MA) the mixture of elemental Ti and B powders in argon atmosphere using a steel jar. The effect of heat of formation and the atomic size factor on MA as well as the phase change during MA were investigated. The amorphization reaction, a common process during MA, had not been observed and the starting raw materials directly converted into final stable phase. When Zr of which atomic radius was larger than that of Ti was substituted for Ti, the alloying time was greatly reduced. On the contrary, substitution of Ta for Ti prolonged the alloying time because of the less negative heat of formation of TaB₂ than that of TiB₂.