Micromechanics of High-Temperature Deformation of Metal-Matrix Composites and Porous Materials

本文将从细观力学的角度研究金属基复合材料的高温变形。这项研究还将包括延性基质中的分布损伤对材料整体随时间变化的行为的影响。根据大多数金属成分除了通常的弹性变形外还可能经历一次蠕变和二次蠕变以及蠕变速率通常与应力呈非线性关系的观察，将研究以下四个具体问题：(1)恒应变率下复合材料的应力-应变关系；(2)较高的蠕变应变范围；以及(4)延伸到更高的颗粒或纤维浓度。这些研究将特别参考实际和潜在的服务环境。只要有可能，将发展简单的宏观本构理论，以反映这些微观力学考虑的本质特征，用于设计和分析。其目的是将这一科学知识转化为使用，以便识别在使用条件下提供最强蠕变抗力的微结构。

High-temperature deformation of metal-matrix composites will be studied from the micromechanics standpoint. The study will also include the influence of distributed damage in the ductile matrix on the overall time-dependent behavior of the material. Guided by the observations that most metallic constituents may undergo both primary and secondary creep in addition to the usual elastic deformation, and that the creep rate usually depends on stress nonlinearly, the following four specific problems will be examined: (1) stress-strain relation of the composite under a constant strain rate, (2) higher creep strain range, and (4) the extension to a higher particle or fiber concentration. These studies will be carried out with a special reference to the practical and potential service environments. Whenever possible, simple macroscopic constitutive theories which can reflect the essential features of these micromechanical considerations will be developed for design and analysis. The aim is to translate this scientific knowledge into use, so that the microstructures which would provide the strongest creep resistance under the service conditions could be identified.