Abstract To gain insights into the relationship between the fracture behavior and the unique microstructure of the in situ TiB2/2024 Al composite, systematic experiments were conducted over wide ranges of temperature (298–673 K), strain rate (0.001–4000/s), and stress triaxiality (−0.82–1.03). The results showed that the strengthening mechanism of the composite was related to Orowan strengthening and coefficient of thermal expansion (CTE) mismatch strengthening. Owing to the smaller particle size and sturdy interfacial bonding, the tensile strength of the in situ nano/submicron TiB2/2024 composite was higher than that of the ex situ composite and the in situ micron composite. Through a morphologic study by scanning electron microscopy (SEM), the microstructural deformation and crack propagation path were found to be largely dependent on the stress state, strain rate, and temperature. The melted matrix precipitated in the dynamic tensile fracture surface can hinder the crack propagation and is considered the determining factor that improves the ductility at room temperature. Furthermore, a 3D fracture locus in the space of the fracture strain, stress triaxiality, and the Lode angle parameter was formed. Finally, a new fracture criterion that considers the Lode angle parameter, the stress triaxiality cutoff value, and the coupling effect of strain rate and temperature was developed. The developed criterion exhibited a robust and accurate capability to describe the fracture behavior of the in situ TiB2/2024 Al composite.

中文翻译：

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应力状态、应变速率和温度对原位 TiB2/2024 Al 复合材料断裂行为的影响

摘要 为了深入了解原位 TiB2/2024 Al 复合材料的断裂行为与独特微观结构之间的关系，在较宽的温度范围 (298–673 K)、应变速率 (0.001–4000/s) 下进行了系统实验。 , 和应力三轴度 (-0.82–1.03)。结果表明，复合材料的强化机制与Orowan强化和热膨胀系数（CTE）失配强化有关。由于较小的粒径和坚固的界面结合，原位纳米/亚微米TiB2/2024复合材料的拉伸强度高于非原位复合材料和原位微米复合材料。通过扫描电子显微镜 (SEM) 的形态学研究，发现微观结构变形和裂纹扩展路径在很大程度上取决于应力状态、应变率和温度。动态拉伸断裂面析出的熔融基体会阻碍裂纹扩展，被认为是提高室温塑性的决定性因素。此外，在断裂应变、应力三轴性和洛德角参数空间中形成了 3D 断裂轨迹。最后，开发了一种考虑 Lode 角参数、应力三轴度截止值以及应变速率和温度耦合效应的新断裂准则。开发的标准表现出强大而准确的能力来描述原位 TiB2/2024 Al 复合材料的断裂行为。动态拉伸断裂面析出的熔融基体会阻碍裂纹扩展，被认为是提高室温塑性的决定性因素。此外，在断裂应变、应力三轴性和洛德角参数空间中形成了 3D 断裂轨迹。最后，开发了一种考虑 Lode 角参数、应力三轴度截止值以及应变速率和温度耦合效应的新断裂准则。开发的标准表现出强大而准确的能力来描述原位 TiB2/2024 Al 复合材料的断裂行为。动态拉伸断裂面析出的熔融基体会阻碍裂纹扩展，被认为是提高室温塑性的决定性因素。此外，在断裂应变、应力三轴性和洛德角参数空间中形成了 3D 断裂轨迹。最后，开发了一种考虑 Lode 角参数、应力三轴度截止值以及应变速率和温度耦合效应的新断裂准则。开发的标准表现出强大而准确的能力来描述原位 TiB2/2024 Al 复合材料的断裂行为。在断裂应变、应力三轴度和洛德角参数的空间中形成了 3D 断裂轨迹。最后，开发了一种考虑 Lode 角参数、应力三轴度截止值以及应变速率和温度耦合效应的新断裂准则。开发的标准表现出强大而准确的能力来描述原位 TiB2/2024 Al 复合材料的断裂行为。在断裂应变、应力三轴度和洛德角参数的空间中形成了 3D 断裂轨迹。最后，开发了一种考虑 Lode 角参数、应力三轴度截止值以及应变速率和温度耦合效应的新断裂准则。开发的标准表现出强大而准确的能力来描述原位 TiB2/2024 Al 复合材料的断裂行为。