(1. 中國工程物理研究院 總體工程研究所，綿陽 621999；
2. 工程材料與結構沖擊振動四川省重點實驗室，綿陽 621999；
3. 中國科學技術大學 中科院材料力學行為與設計重點實驗室，近代力學系，合肥 230027)
摘 要: 在低溫和常溫下，使用準靜態(tài)試驗機和分離式霍普金森桿試驗設備對具有較弱織構特征的TA7鈦合金棒材進行準靜態(tài)和動態(tài)的單向拉伸和壓縮加載試驗，并對加載后的試樣進行EBSD觀察和分析，考察了材料在加載時的孿生行為。結果表明：TA7鈦合金的力學行為具有顯著的應變率相關性和溫度相關性，且其宏觀力學行為表現(xiàn)出拉壓不對稱性。加載過程中，在低溫和高應變率條件下孿晶更容易形成，這種溫度和應變率相關性在壓縮加載時更加顯著。相對于多晶純鈦，TA7鈦合金中的孿晶密度較小，這是由于鋁原子的加入使得孿晶的形成較為困難。TA7鈦合金孿晶形成的難易程度和種類具有拉壓不對稱性，孿晶更易于在壓縮加載時形成。低溫拉伸加載下形成的主要為 孿晶，常溫拉伸變形中形成的主要為 孿晶；高應變率壓縮加載下形成的主要為 孿晶，而低應變率壓縮變形中形成的主要為 孿晶，這與材料的織構是密切相關的。
關鍵字: TA7鈦合金；孿晶；溫度；應變率；拉壓不對稱
（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
