(上海交通大学材料科学系， 上海 200030)
摘 要: 利用TEM原位应变观察技术研究了TiAl合金PST晶体中裂纹扩展过程。发现界面与裂纹的交互作用与界面类型有关，不对称的伪孪晶界面(γ/γP)对裂纹扩展的阻碍最强烈。片层界面以及二次裂纹导致的裂纹分叉是层状组织韧化TiAl合金的重要原因。当裂纹与片层界面的夹角不同时， γ相所表现的两种截然不同的断裂方式表明在TiAl 合金的脆性本质中包含有位错动力学的因素。
关键字: TiAl合金PST晶体 裂纹扩展 位错动力学
（Department of Materials Science, Shanghai Jiao Tong University, Shanghai 200030）
Abstract:Crack propagation processes in polysynthetically twinned (PST) crystals of TiAl were investigated by in-situ TEM observation. It was found that the influence of lamellar boundaries on the fracture behaviors is connected with the type of in terfaces, in which the asymmetrical γ/γP interface is the largest inhibition to crack growth. The crack kinks which result from lamellar interfaces and second microcracks play a dominant role on that TiAl alloys are toughened by lamellar structure. As the angle between tensile axis and lamellar interface varies, that two kinds of different fracture modes existed in γ phase indicates that dislocation dynamics may be an important reason on embrittlement of TiAl alloys.
Key words: PST crystals of TiAl crack propagation dislocation dynamics
