In this study, in-situ tensile deformation behavior of powder metallurgy (PM) Ti6Al4V alloys was investigated to analyze the crack initiation and propagation. Accordingly, the fracture mechanisms of the as-sintered and forged PM alloys were summarized. At the initial stage of plastic deformation, cracks appeared in the stress concentration area of pores in the as-sintered Ti6Al4V alloy, and the crack propagation direction was along the phase boundary. Due to the existence of pores, early fracture was obtained, resulting in low elongation of 6.3%. After forging, the crack initiation occurred between α lamellar structure, and the propagation direction was along the lamellar direction. The fine lamellar structure in different directions in the forged PM Ti6Al4V alloy can hinder the crack propagation, thus improving the plasticity. As a result, better comprehensive mechanical performance was obtained in the forged sample, with UTS of 960 MPa, YS of 850 MPa, and EL of 16%.

在这项研究中，粉末冶金（PM）Ti6Al4V合金的原位拉伸变形行为进行了研究，以分析裂纹的产生和扩展。因此，总结了烧结和锻造的PM合金的断裂机理。在塑性变形的初始阶段，Ti6Al4V烧结合金的气孔应力集中区域出现裂纹，裂纹扩展方向沿相界。由于存在孔，因此可以早期断裂，导致伸长率低至6.3％。锻造后，在α层状组织之间发生裂纹萌生，其传播方向沿层状方向。锻造的PM Ti6Al4V合金在不同方向上的细小层状结构可阻碍裂纹扩展，从而提高塑性。结果是，