Structure and High-temperature Strength of Refractory-Metal Eutectic Composites

研究了由不同熔点和变形特征的相组成的先进金属基复合材料(如共晶复合材料)的变形机制。结合复合材料的微观结构特征，讨论了纤维和基质中不同变形模式对复合材料蠕变行为的影响。建立了一种描述复合材料随时间变化的模型，该模型由弹性纤维缠绕在金属基体中，通过幂律蠕变变形。该理论使用连续介质损伤力学的形式来解释与短纤维相关的端面效应，以及具有不同于纤维或基质的流变性的界面效应。该模型确定了能够显著影响蠕变行为的组成相的重要组织和性能特征。该模型定义了一个界面因子B，它反映了基体与纤维之间应力传递的有效性。决定蠕变性能的重要参数是B、纤维长径比和纤维体积分数。

The deformation mechanisms that can occur in advanced metal matrix composites, such as eutectic composites, consisting of phases with quite different melting points and deformation characteristics are studied. The implications of different deformation modes in the fibers and matrix for the creep behaviour of the composite are considered with particular reference to the microstructural characteristids of the composite. A model describing the time-dependent deformation of a composite consisting of elastic fibers entrained in a metal matrix deforming by power-law creep is developed. The theory uses the formalism of continuum damage mechanics to account for the end effects associated with short fibers and the effects of interfaces with rheological behaviours that differ from either fiber or matrix. The model identifies the important microstructural and property characteristics of the constituent phases that can significantly influence the creep behaviour. The model defines a interface factor B which indicates the effectiveness of stress transfer between matrix and fiber. The important parameters in determining creep performance are B, fiber aspect ratio and fiber volume fraction.