Phase Transformation and Microstructure Evolution in Near-β Ti-7333 Titanium Alloy During Aging
A newly near-β titanium alloy Ti-7Mo-3Cr-3Nb-3Al (Ti-7333) was subjected to β phase solution treatment and ageing in the present work.The characteristics of α phase transformation in ageing treatment were studied.Results show that isothermal aging at a low temperature (350℃) will result in lots of ω particles with small size homogeneously distributing in the parent phase.These ω particles can act as nucleation sites for α phase and lead to the uniform precipitation of fine α phase within the β grain after further ageing treatment.However,when ageing at a higher temperature,the α phase tends to precipitate direct from the β matrix and the morphology of α phase is determined by the temperature and period of ageing treatment.After aging at 550℃ for 5min,acicular α phase precipitates in the β grains as well as along β grain boundaries and the size and quantity of α phase increase with the holding time.Note that Ti-7333 alloy has a quick ageing response.When aging at 700℃ for 1h,coarser α laths precipitate both on the grain boundary and within the grain.Increase the ageing temperature to 800℃,α phase precipitates within the β grain as short rod-like morphology.It is suggested that the driving force for α phase nucleation and the amount of defects in the intragranular decrease with the increasing of temperature,leading to the grain boundaries become the prior nucleation sites.Substantial α phase precipitate-free regions adjacent to β grain boundaries remained after ageing at 700℃ for 1h due to the rejection of β-stabilizer from coarse α lath on β grain boundaries.Aging at 800℃ for 1h resulted in pronounced continuous α-films along β grain boundaries.
Titanium alloy Ageing Microstructure Phase transformation ω phase
Qiong Hui Xiangyi Xue Hongchao Kou Minjie Lai Bin Tang Jinshan Li
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xian 710072, China
国际会议
the Chinese Materials Congress 2012(2012年中国材料大会(CMC2012))
太原
英文
904-911
2012-07-13（万方平台首次上网日期，不代表论文的发表时间）