Non-isothermal Creep of Metal Matrix Composites

本研究将现有的金属基复合材料蠕变变形模型扩展到包括有限纤维/基体界面结合、表现出加工硬化和各向异性的基体材料以及三维微观结构。根据四部分计划，预计将对铝/碳化硅和铜/钨MMC系统进行实验和模拟。(1)用几个新的实验测量了重要的成分和界面性质，并用金相技术确定了显微组织的形态。(2)对两种MMC体系的非等温蠕变速率进行了有限元模拟。稍后将扩展这些模拟，以包括更广泛的微结构、成分和界面属性以及温度/加载路径。(3)用单向拉伸和双向拉伸测量了两种MMC体系的非等温变形速率随温度/载荷路径的变化。(4)对两种体系的实验结果和模型预测进行了比较，建立了基于蠕变寿命的非等温MMC体系寿命估算模型。%目前，人们对适用于要求低密度、高静态强度和良好抗蠕变性能的中等高温结构应用的材料有着浓厚的兴趣。MMC材料表现出其中的一些特性，并有望极大地改善元件的寿命和性能。

This research extends existing models of creep deformation in metal matrix composite (MMC) materials to include limited fiber/matrix interfacial adhesion, matrix materials exhibiting work hardening and anisotropy, and three dimensional microstructures. Experiments and simulations are anticipated for aluminum/silicon carbide and copper/tungsten MMC systems, according to a four part plan. (1) Important constituent and interface properties are measured using several novel experiments and the microstructural configurations are determined using metallographic techniques. (2) Finite element simulations are carried out to predict non-isothermal creep rates in the two MMC systems. These simulations will be expanded later to include a wider range of microstructures, constituent and interface properties, and temperature/load paths. (3) The non- isothermal deformation rates for the two MMC systems are measured in uniaxial tension and biaxial tension as functions of temperature/load paths. (4) The experimental results and model predictions for the two systems are compared and a consistent model for evaluating the creep-based lifetimes of MMC systems with non-isothermal histories are developed. %%% Currently there is a strong interest in materials suitable for moderately elevated temperature structural applications requiring low density, high static strength, and good creep resistance. MMC materials exhibit some of these properties and promise great improvements in component lifetimes and performance.