不同变形方式β型Ti-Mo-Fe合金的低周疲劳性能  

Low-cycle fatigue properties ofβ-type Ti-Mo-Fe alloys with different deformation modes

作　　者：李纵纵 闵小华[1] 毛永换 姚凯 LI Zongzong;MIN Xiaohua;MAO Yonghuan;YAO Kai(School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学材料科学与工程学院,辽宁大连116024

出　　处：《材料工程》2024年第8期130-141,共12页Journal of Materials Engineering

基　　金：国家自然科学基金(52071051)。

摘　　要：利用OM,SEM,EBSD和电液伺服疲劳试验机等研究不同塑性变形方式的Ti-10Mo-xFe(x=1,2,3,质量分数/%)合金的低周疲劳性能,分析总应变幅(Δε_(t)/2=0.5%,1.0%和1.5%)和Fe含量对合金力学响应、组织结构和疲劳裂纹扩展行为的影响。结果表明:随着应变幅和Fe含量的增加,合金的低周疲劳性能下降。各合金的循环应力响应行为普遍表现为初始循环硬化,随后趋于循环稳定或轻微的循环软化,直至断裂失效。Ti-10Mo-1Fe合金的塑性变形由{332}〈113〉孪生主导,随着Fe含量的增加,合金的塑性变形方式向位错滑移转变。低应变幅下Ti-10Mo-1Fe合金疲劳源区孪晶数量较少,沿裂纹扩展方向孪晶数量逐渐增加;高应变幅下近断口区域出现大量孪晶。Ti-10Mo-1Fe合金中孪晶的大量产生及交割将晶粒内部分割成网状组织,从而起到细化晶粒的作用,有效释放应力集中并延缓疲劳裂纹的萌生。同时微裂纹扩展至孪晶界附近时发生裂纹偏折,合金中大量的孪晶界有效延长疲劳裂纹扩展路径。The low-cycle fatigue(LCF)behavior of Ti-10Mo-xFe(x=1,2,3,mass fraction/%)alloys with different plastic deformation modes were investigated by OM,SEM,EBSD and electro-hydraulic fatigue test machine.The effects of the strain amplitudes(Δε_(t)/2=0.5%,1.0%and 1.5%)and Fe content on the mechanical response,microstructures and fatigue crack propagation behavior were analyzed.The results show that the low-cycle fatigue performance of the alloys decreases with the increase of strain amplitude and Fe content.The cyclic stress response behaviors generally exhibit an initial cyclic hardening and then tend towards a cyclic stability or slight cyclic softening until fracture.The plastic deformation mode of Ti-10Mo-1Fe alloy is dominated by{332}〈113〉twinning,and changes to dislocation slip with the increase of Fe content.A few twins are formed in the fatigue initiation region of Ti-10Mo-1Fe alloy under low strain amplitude,and the twin area fraction increases gradually along the crack propagation direction,while a large number of twins are activated near the fracture area under high strain amplitude.The activation and intersection of abundant twins in Ti-10Mo-1Fe alloy divide the grain into network microstructures,which effectively release the stress concentration and delay the initiation of fatigue crack due to the dynamic microstructure refinement effect.At the same time,the abundant twin boundaries significantly extend the fatigue crack propagation path because the micro-crack deflects along the twin boundaries.

关 键 词：Β型钛合金 低周疲劳 孪生诱发塑性效应 {332}〈113〉孪生 位错滑移 

分 类 号：TG146.2[一般工业技术—材料科学与工程]