Thermal-Expansion Behavior of Two-Phase Solids

Abstract

The thermal expansion behavior of the two duplex systems, lead‐fused silica and aluminum‐silicon, has been investigated experimentally above and below room temperature. The microstructure in the first case consisted of fused silica particles in a lead matrix, while silicon constituted the dispersed phase in the second. The expansion coefficients always fell below those predicted by the simple rule of mixtures. A model is proposed and a new formula for the calculation of the thermal expansion coefficient of duplex materials is derived. The new formula fits experimental results better than Turner's formula. The role of microplastic yielding in high‐inclusion‐content composites is discussed.