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

本文将从微观力学的角度研究金属基复合材料的高温变形。该研究还将包括延性基体中分布损伤对材料整体随时间变化行为的影响。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，并且蠕变速率通常取决于应力非线性，根据这一观察结果，将研究以下四个具体问题：(1)复合材料在恒定应变速率下的应力-应变关系；(2)较高的蠕变应变范围；(4)扩展到较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进行。只要有可能，可以反映这些微观力学考虑的基本特征的简单宏观本构理论将被开发出来用于设计和分析。目的是将这些科学知识转化为应用，以便确定在使用条件下提供最强抗蠕变性能的微观结构。

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.