Ti-5Mo-5V-2Cr-3Al合金中的冲击相变研究

Impact Induced Phase Transformation in Ti-5Mo-5V-2Cr-3Al Alloy

利用Hopkinson压杆装置,对Ti-5Mo-5V-2Cr-3Al(TB10)合金进行高速冲击试验,采用光学显微镜和透射电镜分析其冲击相变与动态承载能力之间的关系。结果表明,显微组织状态对绝热剪切敏感性影响很大,在相同的应变率条件下,两相区固溶+时效、两相区固溶+双重时效的TB10合金试样中均可观察到明显的绝热剪切带,且沿剪切带出现裂纹,而固溶态试样晶粒的变形是均匀的,没有观察到绝热剪切带,其相对于前两者是绝热剪切不敏感的组织状态;在高应变率下,固溶态的试样发生了应力诱发马氏体相变;β晶粒内的条状析出物是由β相和斜方马氏体相混合构成;由于相变过程吸收了一部分冲击功,使试样未能达到材料本构失稳形成ASB的临界条件,且应力诱发马氏体相具有较高的均匀伸长率及较大的塑性,使试样仍具有较好的动态承载能力。

Dynamic testing of Ti-5Mo-5V-2Cr-3Al（TB10） alloy was carried out by a split Hopkinson pressure bar（SHPB） technique.The results showed that the strain rate sensitivity was deeply influenced by microstructure.With the same strain rate,adiabatic shear bands were observed in TB10 alloy samples which were in the solution treated and ageing（STA）,and,solution treated and diplex ageing（STDA）.Moreover,there were cracks along the adiabatic shear bands.Meanwhile,there was no adiabatic shear band observed in the sample which was in the solution treated condition,the deformation of its grain was homogeneous,and it was relatively insensitive to adiabatic shearing sensitivity.Under high strain rate,stress-induced martensite phase transformation happened to the sample in the solution treated condition.The educt with list structure within the β-grain was made up of β-phase and martensite phase.Because some of the impact power was consumed in the transformation process,the sample avoided reaching the critical condition of material destabilization and forming ASB,and the stress-induced martensite phase had high uniform elongation and biggish plasticity,so the sample still had good dynamic bearing capacity.