Non-isothermal Creep of Metal Matrix Composites

本研究扩展了现有的金属基复合材料（MMC）蠕变模型，包括有限的纤维/基体界面粘附，基体材料表现出加工硬化和各向异性，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)利用几个新颖的实验测量了重要的成分和界面性能，并利用金相技术确定了显微组织构型。(2)对两种MMC体系的非等温蠕变速率进行了有限元模拟。这些模拟将在稍后进行扩展，以包括更广泛的微观结构、成分和界面特性以及温度/负载路径。(3)在单轴拉伸和双轴拉伸下，测量了两种MMC体系的非等温变形率作为温度/载荷路径的函数。(4)比较了两种体系的实验结果和模型预测，建立了非等温历史MMC体系蠕变寿命的一致性模型。目前，人们对适合中等高温结构应用的材料有浓厚的兴趣，这些结构应用需要低密度，高静态强度和良好的抗蠕变性能。MMC材料表现出这些特性，并承诺在组件寿命和性能方面有很大的改进。

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.