Ultrasonic propagation in metal-matrix-composites

Ultrasonic scattering at phase and grain boundaries in composites causes attenuation of sound waves and dispersive sound velocities. This effect can be used for nondestructive materials characterization if it can be described quantitatively. This paper presents a theory which allows calculation of the velocities and scattering coefficients of compressional and shear ultrasonic waves in fibre reinforced composites as function of frequency. To begin with, the polycrystalline structure of matrix and fibres is neglected and an exactly parallel alignment of the fibres is assumend. The structure anisotropy causes directional dependent sound velocities and scattering coefficients. Numerical evaluation was done for SiC-fibre reinforced aluminium.