Study on Phase Transformation of TC21 Alloy During Aging Treatment
Phase transformation during solution treatment,the decomposition mechanism and microstructure evolution of α" phase during aging treatment were systematically studied using XRD,SEM,TEM and microhardness analysis.The results show that TC21 alloy solution treated at 1000 ℃ for 30 min,water quenched,present an martensitic structure consisting of α" phase and little β phase,O phase (Ti2AlNb).With the increase of aging temperature,the mechanism of the decomposition of α" phase is α"→α+α"富→α+β亚稳→α+β,α"+α'+β亚稳→α+β,α"→α+β.The microhardness of TC21 alloy depends on the aging temperature and aging time.The microhardness increases rapidly,reachs the maximum and gradually decreases with increasing aging time,with increasing aging temperature,the time to reach the maximum microhardness and the final microhardness of TC21 alloy decreases.