中文摘要：

评价了常规铸造Ti-47.5Al-2.5V-1.0Cr（at%）合金定向层片组织的室温拉伸性能和断裂韧性,并结合断口形貌分析其断裂行为。结果表明：该定向层片组织在承受平行于层片界面载荷作用时,表现出优异的室温抗拉强度和塑性组合,且其室温拉伸塑性可达到3.8%,明显优于其他铸造TiAl合金。其较高的室温拉伸塑性归因于定向层片组织的一致性和穿层断裂区发生较大程度的塑性变形。定向层片组织室温拉伸的主要断裂模式是穿层断裂,断裂起源于层片界面端部垂直于试样表面的TypeⅡ层片区域,而不是层片界面平行于试样表面的TypeⅠ层片区域。其主要原因是TypeⅡ层片具有比TypeⅠ层片低的裂纹萌生和扩展抗力。

英文摘要：

Room temperature tensile properties and fracture toughness of cast Ti-47.5Al-2.5V-1.0Cr （at%） alloy containing the directional lamellar structure were evaluated and the fracture behavior was analyzed. The results indicate that the directional lamellar structure possesses excellent balance between tensile strength and ductility along lamellar boundary at room temperature, and its tensile ductility could be up to 3.8% at room temperature, which is much higher than that of other advanced east gamma TiAl alloy. It is attributed to uniformity of the directional lamellar together with certain plastic deformation at the translamellar fracture region. The main fracture mode of the directional lamellar structure is translamellar fracture. And the fracture is not originated from Type I lamellar region with lamellar boundary parallel to the sample surface, but from Type II lamellar region with lamellar boundary perpendicular to the sample surface, which is predominantly due to higher crack initiation and propagation resistance of Type I than Type II.