摘要
First-principles calculations were performed to investigate the structures and energetics of {101n} coherent twin boundaries(CTBs) and glide twin boundaries(GTBs) in hexagonal close-packed(hcp) Ti. The formation mechanism of GTBs and their correlation with twin growth were fundamentally explored. Results suggested that GTBs can form from the gliding of CTBs, through their interaction with basal stacking fault. The gliding eventually restored the CTB structures by forming a pair of single-layer twinning disconnections. The pile-up of twinning disconnections should be responsible for the wide steps at twin boundaries as observed in high-resolution transmission electron microscopy, which can further promote twin growth. Possible effects of various alloying elements on pinning twin boundaries were also evaluated, to guide the strengthening design of Ti alloys.
基于第一性原理计算研究密排六方结构钛中{101n}共格孪晶界和滑移孪晶界的结构和能量,探讨滑移孪晶界的形成机理及其与孪晶生长的关系。结果表明,共格孪晶界与基面堆垛层错的相互作用可使共格孪晶界产生滑移,从而形成对应的滑移孪晶界。这种滑移最终能在孪晶界处形成一对单层孪生台阶,并恢复共格孪晶界的结构。孪生台阶的塞积可导致高分辨率透射电镜观察到的孪晶界上的台阶宽化,进一步促进孪晶的生长。此外,还评估多种合金化元素对孪晶界滑移的钉扎效应,为钛合金的强化设计提供指导。
基金
the financial support from the National MCF Energy R&D Program of China (2018YFE0306100)
the National Natural Science Foundation of China (51971249)
the State Key Laboratory for Powder Metallurgy,Central South University,Changsha,China
