Abstract Interfaces can act as dislocation obstacles, sinks or dislocation sources and, therefore, influence strongly the mechanical properties of metals. To consider these effects at high temperature creep, a three-dimensional gradient crystal plasticity model is introduced. The interaction between dislocations and the fiber-matrix interface is included by an interface flow rule, which accounts for the gradient stresses and the normal component of the Cauchy stress on the interface. Motivated by the interface-enriched generalized finite element method (IGFEM), continuous shape functions allowing for weak discontinuities are introduced. These shape functions are used to evaluate the interface flow rule at sharp interfaces and are validated by comparing numerical simulation results of a laminate for single slip with an analytical solution. To investigate the slip transfer/activation at the interface, the directionally solidified NiAl-9Mo composite is modeled as regular fibrous microstructure. The simulated creep curves agree well with experimentally measured ones. It is found that the stress dependency of the interface flow rule is necessary to reproduce the well known composite's Norton behavior. The simulations reveal that the creep behavior of the composite is mainly controlled by the fibers and the interface properties. Finally, the specific shape of the creep curve could be explained.

中文翻译：

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一种梯度塑性蠕变模型，用于评估金属间化合物 NiAl-9Mo 的界面处滑移转移/活化

摘要 界面可以作为位错障碍、汇或位错源，因此强烈影响金属的机械性能。为了考虑高温蠕变时的这些影响，引入了三维梯度晶体塑性模型。位错与纤维-基质界面之间的相互作用包含在界面流动规则中，该规则解释了梯度应力和界面上柯西应力的法向分量。在界面丰富的广义有限元方法 (IGFEM) 的推动下，引入了允许弱不连续性的连续形状函数。这些形状函数用于评估尖锐界面处的界面流动规则，并通过比较单滑的层压板的数值模拟结果与解析解来验证。为了研究界面处的滑移转移/活化，定向凝固的 NiAl-9Mo 复合材料被建模为规则的纤维微观结构。模拟的蠕变曲线与实验测量的曲线非常吻合。发现界面流动规则的应力依赖性对于重现众所周知的复合材料的诺顿行为是必要的。模拟结果表明，复合材料的蠕变行为主要受纤维和界面特性的控制。最后，可以解释蠕变曲线的具体形状。发现界面流动规则的应力依赖性对于重现众所周知的复合材料的诺顿行为是必要的。模拟结果表明，复合材料的蠕变行为主要受纤维和界面特性的控制。最后，可以解释蠕变曲线的具体形状。发现界面流动规则的应力依赖性对于重现众所周知的复合材料的诺顿行为是必要的。模拟结果表明，复合材料的蠕变行为主要受纤维和界面特性的控制。最后，可以解释蠕变曲线的具体形状。