(1. 中国工程物理研究院 总体工程研究所，绵阳 621999；
2. 工程材料与结构冲击振动四川省重点实验室，绵阳 621999；
3. 中国科学技术大学 中科院材料力学行为与设计重点实验室，近代力学系，合肥 230027)
摘 要: 在低温和常温下，使用准静态试验机和分离式霍普金森杆试验设备对具有较弱织构特征的TA7钛合金棒材进行准静态和动态的单向拉伸和压缩加载试验，并对加载后的试样进行EBSD观察和分析，考察了材料在加载时的孪生行为。结果表明：TA7钛合金的力学行为具有显著的应变率相关性和温度相关性，且其宏观力学行为表现出拉压不对称性。加载过程中，在低温和高应变率条件下孪晶更容易形成，这种温度和应变率相关性在压缩加载时更加显著。相对于多晶纯钛，TA7钛合金中的孪晶密度较小，这是由于铝原子的加入使得孪晶的形成较为困难。TA7钛合金孪晶形成的难易程度和种类具有拉压不对称性，孪晶更易于在压缩加载时形成。低温拉伸加载下形成的主要为 孪晶，常温拉伸变形中形成的主要为 孪晶；高应变率压缩加载下形成的主要为 孪晶，而低应变率压缩变形中形成的主要为 孪晶，这与材料的织构是密切相关的。
关键字: TA7钛合金；孪晶；温度；应变率；拉压不对称
（1. Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 621999, China;
2. Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province, Mianyang 621999, China;
3. CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China）
Abstract:Quasi-static and dynamic uniaxial tension and compression experiments were performed on weakly textured TA7 titanium alloy rod at low temperatures and room temperature by using quasi-static testing machine and Hopkinson bar apparatus, respectively. The EBSD observation and analysis was conducted for the deformed samples. Deformation twinning behavior of the alloy during the plastic deformation was investigated. The experimental results show that the mechanical behavior of TA7 titanium alloy is sensitive to strain rate and temperature, and the mechanical response of TA7 titanium alloy shows tension-compression asymmetry. The deformation twins are easier to form at low temperatures and high strain rates, which is more significant under compression loading. The deformation twin density in TA7 titanium alloy is lower than that in pure titanium, which is attributed to the addition of aluminum atoms inhibiting the deformation twinning. The formation ability and type of the deformation twin show tension-compression asymmetry, and deformation twins are more likely to form in compression. The deformation twin occupies the low temperature tension deformation. The deformation twin is more likely to be activated in tension at room temperature. The deformation twin and the deformation twin dominate high strain-rate and quasi-static compression deformations, respectively. The tension-compression asymmetry of deformation twin is closely related to the texture of the alloy.
Key words: TA7 titanium alloy; deformation twinning; temperature; strain rate; tension-compression asymmetry
