Residual strain energy in composites containing particles

Selsing's formula for radial tension at the particle-matrix interface is extended into a general formula which includes the effects of the amount of dispersed particles. A relationship is derived between individual volumes of strained unit cells in the crystal lattices of the particles and of the surrounding matrix. These relationships are used to predict the effect of the particles (2H-TiB2, 2H-ZrB2, and t-WB) on their unit cells and on the unit cell of the surrounding 6H-SiC matrix. The precision of these predictions was 7.1% or better. Hence, in principle, it is possible to investigate the distributions of residual bulk stress/strain. Estimates of characterizing values of the three composite systems are attempted on the rough basis of the elastic constants of the SiC matrix, confirming the physical validity of this approach as a first approximation. Further, the residual bulk strain energies of the particles and the matrix are discussed in connection with the elastic term involved in the fracture energy of such composites.