Ti-10V-2Fe-3Al合金低温时效的相变行为及其对力学性能的影响

Phase Transformation Behavior and Mechanical Properties of Ti-10V-2Fe-3Al Alloy Subjected to Low Temperature Aging

研究了低温时效对Ti-10V-2Fe-3Al合金相变行为和力学性能的影响。时效形貌观察显示,随时效时间的延长,在β基体中持续析出等温ω相粒子及发生等温马氏体相变;当时效时间超过4 h后,ω粒子逐渐消失,但等温马氏体相变继续进行。拉伸测试结果显示,经0.5 h时效后,样品的塑性最好,屈服强度较低;延长时效时间,塑性急剧下降,强度持续增大。超过4 h后,塑性开始缓慢回升,强度仍然增大。分析表明,0.5 h时效样品良好的塑性源于拉伸时的相变诱发塑性效应;ω相的脆化作用和等温马氏体相变对β基体的消耗使得样品的塑性降低,强度增大;当时效时间大于4 h后,ω相的消失以及大量等温马氏体的形成有利于塑性回升及强度增大。

The influence of low temperature aging on phase transformation behavior and mechanical properties of Ti-10V-2Fe-3Al alloy has been investigated.Results show that isothermal ω particles and α″ martensitic plates are continuously formed in the β matrix with increasing aging time.When the aging time is more than 4 h,ω particles gradually disappear and lots of isothermal martensites are still produced.Tensile testing shows that,the 0.5 h-aged specimen has the highest plasticity and lower yield strength than other specimens.With increasing aging time,plasticity is decreased sharply and strength is increased rapidly.However,plasticity is recovered slowly and strength is increased continuously once the aging time is more than 4 h.Comprehensive analysis indicates that good plasticity of the 0.5 h-aged specimen is attributed to transformation-induced plasticity effect（TRIP） during tensile process.Embrittlement induced by ω particles and consumption of β matrix due to isothermal martensitic transformation results in reduction of plasticity and increment of strength.On the contrary,when the aging time is longer than 4 h,disappearance of ω particles and formation of plenty of isothermal martensites are beneficial for the increment of both strength and plasticity.