Acoustic nonlinearity in metal-matrix composites

The results of this study show that the acoustoelastic constatns and the acoustic nonlinearity parameter are influenced by the amount of reinforcement in metalmatris composites. Therfore, they are promising candidates to characterize the mechanical bahavior of MMCs nondestructively. Also, the two quantities clearly indicate a decreasing elastic nonlinearity of the composite with the increasing content of SiC. The nonlinearity parameter changes linearly as a function of second phase content.the absolute values of the claculated as well as of the directly measured acoustic nonlinearity parameter are in good agreement within the accuracy of the measurements. This shows that both techniques, measurements of absolute amplitudes using the capactive gap receiver and measurementsof the acoustoelastic effect, are suitable methods for the determination of the nonlinearity parameter.