Characterization of state and properties of Al-based MMC-components by ultrasonic techniques

In a comprehensive experimental study ultrasonic techniques are optimized and used to characterize the state abd to evaluate the properties of Al-based Al2O3 fiber reinforced MMC-parts. It has been the objective to concentrate on those ultrasonic techniques which can be applied on real parts in order to demnonstrate the ultrasonic potential in a quality assurance concept for MMC-mass products, like automotive pistons and con-rods. It is found that the ultrasonic backscattering to visuakize the distribution of the reinforcing phase in surface layers as well as in bulk of components is very informative although the results are of qualitative nature only. The evaluation of quantitative values of the local concentration on reinforcements as well as the Young's and shear moduli are possible by measuring the ultrasonic velocities or time-of-flight. Information on the elastic anisotropy resp. isotropy is gained from measurements using linear polarized shear waves. The pulse distortion of a l ongitudinal wave is found to be suitable to detect misalignments of continous fibers. Compared with the established techniques to characterize the local distribution of reinforcement, to evaluate elastic constants and to inspect the long fiber alignments, the ultrasonic techniques have the advantage help for the optimization of manufacturing parameters.