Effects of Variable Phase Volume Fractions on the Effective Thermo-Mechanical Properties of Metal-Ceramic Composites With Graded Microstructures

Abstract

The present paper is specifically concerned with the evaluation of the effective temperature-dependent elastic, thermal and thermo-elastic material properties of artificially graded Ti-TiB2 microstructures (through thickness only). Effective properties of Ti-TiB2 composite are obtained using micromechanics models and finite element analysis of representative volume elements (RVEs). Two approaches have been adopted and compared to determine the proper RVE. In a fashion similar to previous studies [1], RVEs are generated by considering regions that have a uniform to slow variation in material composition (i.e., constant volume fraction), resulting in statistically homogenous piece-wise RVEs of the graded microstructure neglecting interaction from neighboring cells. In the second approach, continuous RVEs are generated by considering the entire FGM. As pointed out by Anthoine [2], modeling of the complete variation in a microstructure may influence the surrounding layers due to the interactions of varying material composition, particularly when there is a steep variation in material composition along the grading direction. To determine these effects of interlayer interactions, FGM microstructures were generated using three different types of material grading functions, linear, quadratic and square root, providing uniform, gradual and steep variations, respectively. Finite element analysis was performed to determine effective properties of the composite over a wide temperature range.