Whether a metallic material fractures by brittle cleavage or by ductile rupture is primarily governed by the competition between cleavage and dislocation emission at the crack tip. The linear elastic fracture mechanics (LEFM) based criterion of Griffith, respectively the one for dislocation emission of Rice, are sufficiently reliable for determining the possible crack tip propagation mechanisms in isotropic crystalline metals. However, the applicability of these criteria is questionable when non-cubic, anisotropic solids are considered, as e.g. ordered intermetallic TiAl phases, where slip systems are limited and elastic anisotropy is pronounced. We study brittle versus ductile failure mechanisms in face-centered tetragonal TiAl and hexagonal Ti 3 Al using large-scale atomistic simulations and compare our findings to the predictions of LEFM-based criteria augmented by elastic anisotropy. We observe that the augmented Griffith and Rice criteria are reliable for determini...

中文翻译：

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纯I型载荷下有序金属间TiAl合金的各向异性破坏行为

金属材料是通过脆性断裂还是通过韧性断裂而断裂，主要取决于裂纹尖端处的断裂与位错释放之间的竞争。基于格里菲斯的线性弹性断裂力学（LEFM）准则（分别是莱斯的位错排放的准则）对于确定各向同性晶体金属中可能的裂纹尖端传播机制具有足够的可靠性。然而，当考虑非立方各向异性的固体时，例如有序金属间化合物TiAl相，其中滑移系统受到限制，弹性各向异性明显，因此这些标准的适用性值得怀疑。我们使用大规模原子模拟研究面心四方TiAl和六方Ti 3 Al中的脆性与延性破坏机制，并将我们的发现与基于弹性各向异性增强的基于LEFM的标准的预测进行比较。我们观察到增强的格里菲斯和赖斯标准对于确定...