Effect of Cooling Mode for Heat Treatment on Microstructure and Hardness of TC4 Alloy Prepared by TiH₂ Powder Metallurgy

TC4 alloy prepared by TiH₂ powder metallurgy was subjected to heat treatment and the effects of different cooling methods on microstructure and hardness of the TC4 alloy were studied. The results show that both solid solution treatment and aging treatment can densify the alloy. In addition, the cooling method of solid solution treatment can significantly affect the proportion of α phase and β phase in the TC4 alloy, resulting in the change of microstructure. The recrystallization in the air-cooled sample produces fine equiaxed structure with the smallest average grain diameter. Solid solution treatment can significantly increase the hardness of the alloy.