电冲击处理(EST)对TC11钛合金微结构和力学性能的影响研究

Investigation on microstructure variation and mechanical properties of TC11 titanium alloy after electro-shocking treatment(EST)

为寻求优化钛合金组织和力学性能的新思路,本文采用电冲击处理方法对TC11钛合金进行组织结构调控,并利用SEM和EBSD对处理前后材料的微结构、相含量和织构分布进行表征分析,同时利用处理前后的硬度分布和压缩性能分析来体现力学性能变化。微结构研究表明,当电冲击处理时间增加至0.04 s,材料发生针状二次α向β相转变,β相含量从10.1%增加到14.4%,且初生α/β相界面平滑度增加,主要归因于电冲击处理过程的热效应和非热效应。织构研究表明,电冲击处理0.04 s后,α相织构强度从6.77增大到10.53,β相织构强度增加不明显,α相和β相织构变化与电冲击处理能量集中引起的相变有关。力学性能研究结果显示,电冲击处理0.06 s后,显微硬度和屈服强度明显提高,主要原因是样品内部析出大量细小的针状马氏体α相,起到弥散强化作用。综上,利用电冲击处理来调控钛合金微结构将是一种新的探索,可为钛合金力学性能改善提供一条新途径。

To seek new ideas for optimizing microstructure and mechanical properties of titanium alloys, this paper evaluates the microstructure variation and mechanical properties of TC11 alloy after electro-shocking treatment(EST). The microstructure, phase content, and texture distribution of the material before and after EST were characterized by SEM and EBSD.Meanwhile, the hardness distribution and compression properties were analyzed to reflect the variation of mechanical properties of TC11 before and after EST.Results of microstructure variation show that with the increase of EST time to 0.04 s, the transformation of the acicular secondary from α to β during EST occurred, and the content of β phase increased from 10.1% to 14.4%.Moreover, the smoothness of primary α/β interface increased, which can bemainly attributed to the thermal and non-thermal effects of EST. Texture studies show that after EST for 0.04 s, the texture intensity of α phase increased from 6.77 to 10.53, but the increase of the texture intensity of β was not obvious. The texture directions of both α and β phases were changed under EST, and the variation of the texture was related to the phase transformation caused by the energy concentration during EST. The investigation on the mechanical properties show that the hardness and yield strength increased significantly after EST for 0.06 s, and the main reason was that a large number of fine acicular martensite α was precipitated, playing the role of dispersion strengthening inside the sample. In conclusion, it is a novel exploration to modify the microstructure of titanium alloys by EST, which can provide a new way to improve the mechanical properties of titanium alloys.