(1. 长安大学 材料科学与工程，西安 710064；
2. 西安赛特思迈钛业有限公司，西安 710016；
3. 中国石油集团石油管工程技术研究院，西安 710077；
4. 西北有色金属研究院，西安 710016)
摘 要: 本文研究了近β-Ti合金、近α-Ti合金和(α+β)-Ti合金在0~-110 ℃、频率为200 Hz简谐振动过程中的振动模量及裂纹扩展行为，分析了温度对简谐振动中裂纹扩展速率及位错分布的影响，揭示了裂纹扩展机制。结果表明：低温下的简谐振动会加剧位错堆积与缠绕，从而增大阻尼，降低钛合金的振动回弹能力，提升钛合金的减振性能。其中，近β-Ti合金的储能模量整体比近α-Ti合金的低28.97%，其损耗模量和阻尼分别比(α+β)-Ti合金的高16.4%和9.88%，其低温下的减振性能优于其他两种钛合金。简谐振动在β相内产生的位错在相界累积并向相内滑移，导致应力集中和界面处微裂纹的产生，进而发生穿晶断裂。此外，伴随着β相中二次裂纹的产生，裂纹尖端受到不同方向的阻力，消耗了额外的简谐振动能量，尤其是当温度低于-60 ℃时，次生裂纹有效延缓了裂纹扩展速率。简谐振动在α相内产生的位错首先在相内被激活并不断向相界堆积，导致相内能量高于相界，裂纹发生沿晶扩展。在-60~-110 ℃温度区间，更低的损耗模量和阻尼使简谐振动能量作用在裂纹沿晶扩展上，增大了α相裂纹扩展速率。
关键字: 典型钛合金；储能模量；损耗模量；阻尼；裂纹扩展
（1. School of Materials Science and Engineering, Chang’an University, Xi’an 710064, China;
2. Xi’an Scitech Titanium Industry Co., Ltd., Xi’an 710016, China;
3. CNPC Tubular Goods Research Institute, Xi’an 710077, China;
4. Northwest Institute for Non-Ferrous Metal Research, Xi’an 710016, China）
Abstract:In this paper, the vibration modulus and crack propagation behavior of near β-Ti alloy, near α-Ti alloy and (α+β)-Ti alloy under harmonic vibration at the temperature range from 0 ℃ to -110 ℃ and frequency of 200 Hz were studied. The influence of temperature on crack propagation rate and dislocation distribution in harmonic vibration was analyzed, and the crack propagation mechanism was revealed. The results show that harmonic vibration at low temperature will aggravate dislocation accumulation and entanglement, thereby increasing damping, which reduces the vibration resilience of titanium alloys, can improve the vibration reduction performance of titanium alloys. The overall storage modulus of near β-Ti alloy is 28.97% lower than that of near α-Ti alloy, the loss modulus and damping are 16.4% and 9.88% higher than those of (α+β)-Ti alloy, respectively. The vibration reduction performance of near β-Ti alloy at low temperature is better than other two titanium alloys. The dislocations generated by the harmonic vibration in the β phase accumulate at the phase boundary and slip into the phase, leading to stress concentration and the generation of microcracks at the interface, and transgranular fracture occurs then. In addition, with the occurrence of secondary cracks in the β phase, the crack tip is subjected to resistance in different directions, which consumes additional harmonic vibration energy. When the temperature is lower than -60 ℃, the crack growth rate is delayed. The dislocations generated by the harmonic vibration in the α phase are first activated in the phase and continue to accumulate to the phase boundary, resulting in higher energy in the phase than that of the phase boundary, and intergranular fracture occurs then. In the temperature range from -60 ℃ to -110 ℃, the lower loss modulus and damping make the harmonic vibration energy act on intergranular fracture, which increases the crack propagation rate of α phase.
Key words: typical titanium alloy; storage modulus; loss modulus; tan delta; crack propagation
