论文部分内容阅读
采用感应凝壳熔炼技术和熔模铸造方法制备TiAl合金。在增量加载情况下,采用扫描电镜原位观察技术观察带缺口的熔模铸造TiAl合金试样的裂纹扩展和断裂特性。在拉伸变形的整个过程中,观察并分析裂纹萌生、扩展直至断裂的全过程。结果表明,TiAl合金的断裂机制不仅对于缺口区域附近的微裂纹敏感,而且与层片方向和加载轴的位向有关。当局部应力大于TiAl合金的断裂韧性时,高的拉伸应力就会导致裂纹萌生、扩展直至断裂失效。因此,TiAl合金的塑性和高的拉伸应力导致带缺口的TiAl合金的断裂失效。
TiAl alloy was prepared by induction shell melting technology and investment casting method. In the case of incremental loading, the crack growth and fracture characteristics of notched investment cast TiAl alloy specimens were observed by scanning electron microscope in situ observation. In the whole process of tensile deformation, the initiation and propagation of cracks are observed and analyzed until the whole process of fracture. The results show that the fracture mechanism of TiAl alloy is not only sensitive to the micro-cracks in the vicinity of the notched region but also related to the orientation of the lamella and the orientation of the loading axis. When the local stress is greater than the fracture toughness of TiAl alloy, high tensile stress will lead to crack initiation and propagation until fracture failure. Therefore, the plasticity and high tensile stress of the TiAl alloy lead to failure of the fracture of the notched TiAl alloy.