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通过对裂纹与晶内片层和晶界的交互作用的原位观察 ,研究了全层状组织 Ti Al基合金的断裂机制。结果表明 :裂纹萌发和扩展方式不仅依赖于片层与拉伸轴的相对取向 ,还受晶界取向的制约。当片层与拉伸轴成较大角度时 ,沿片层裂纹扩展是通过主裂纹与沿片层微裂纹的连接及剪切的过程 ;而当拉伸轴近平行片层时 ,跨片层裂纹依靠对界面分离和跨片层微裂纹这两种形式的微裂纹的连接进行扩展的。纵向交叉晶界有利于断裂韧性的提高 ,而横向晶界则不利于材料断裂韧性。
In-situ observation of the interaction between the crack and the intragranular lamellae and grain boundaries, the fracture mechanism of TiAl-based all-layer structure was studied. The results show that the mode of crack initiation and propagation depends not only on the relative orientation of the sheet and the stretching axis but also on the orientation of the grain boundaries. When the sheet is at a large angle to the stretching axis, the crack propagation along the sheet passes through the process of the connection and shearing of the main crack with the microcracks along the sheet. When the stretching axis is parallel to the sheet, Cracks are extended by the connection of two forms of microcracking, such as interface separation and inter-lamellar microcracking. Longitudinal cross grain boundary is conducive to the improvement of fracture toughness, while the transverse grain boundaries are not conducive to the fracture toughness of the material.