Abstract
The thermomechanical properties of composite materials are influenced by various factors such as defects, reactions between matrix and fillers, orientation of fillers, mismatch of the coefficient of thermal expansion (CTE) between the matrix and the fillers.The effect of these factors on the thermomechanical properties of sintered composites is estimated theoretically and the theoretical evaluations are compared with the experimental data.The theory used in this calculation is based on Eshelby's equivalent inclusion method, with which we can solve the three-dimensional elastic problem by assuming ellipsoidal fillers to be embedded in an infinite elastic body.This method applies to various types of fillers by changing the aspect ratio of the ellipsoidal fillers such as: long fibers, whiskers, spherical particles and so on.Within this formalism, we have analyzed the effects on the thermomechanical properties of composites of interface debonding between matrix and fillers, dispersion of pores, phase reactions among constituent phases, anisotropically dispersed fillers, residual stress induced by shape memory effect, and CTE mismatch between matrix and fillers.
The microstructure of the sintered composites, can be controlled widely by changing the mixtures of powders, sintering conditions and the heat treatment, thereby we can obtain specimens with a variety of thermomechanical properties. In this study, the microstructural parameters for Eshelby's analysis have been determined directly from microstructural observations of the composites, and the thermomechanical properties have been predicted theoretically using the observed data.We have got an excellent agreement between the experimentally determined thermomechanical data and the theoretical predictions.It has been shown that the present method will be a versatile tool for the analysis of the properties of the sintered composites, as well as for their material design.
