全层状TiAl基合金损伤断裂行为的研究

Damage fracture behaviors of fully lamellar TiAl based alloys

通过拉伸及卸载试验,对试样断口与表面进行SEM观察分析,研究TiAl基合金拉伸损伤与断裂行为。结果表明:该材料拉伸的弹性阶段范围很窄,塑性变形能力差,在拉伸卸载试样表面观察不到微裂纹和损伤;而在试样断口上有唯一起裂源和发散状的河流花纹。断裂过程为:当试样被加载至一定应力时,在其应力最大截面附近某一材料组织薄弱处率先产生一定尺寸的Griffiths裂纹源,并很快由此起裂源朝多个有利取向快速解理扩展,并导致试样最后完全断裂。

Based on the results of loading and unloading tensile test, and observations of corresponding cracks and fracture surfaces for TiAl based-alloys, tensile damage and fracture behaviors were studied. The results show that the elastic tensile range is narrow, and the plastic deformability is poor. No microcracks or damage can be observed on the specimen surface after loading and unloading. Only one initiation crack and divergent river pattern in the propagation path can be found on fractured surfaces of specimen. The fracture process is that, under tensile loading, a certain size Griffiths crack is successively initiated at the weakest point near maximum stress section of the specimen, and propagates rapidly in different easy orientation, thus leading to the final failure of specimen.