Nondestructive characterization of metal-matrix composites.
Zerstörungsfreie Bestimmung von Metall-Matrix-Verbundwerkstoffen
Metal-matrix composites are emerging as advanced materials for applications requiring high performance isotropic mechanical properties. The development of methods for the nondestructive characterization of these materials is essential to their manufacturing and processing. The work described in this paper deals with the ultrasonic characterization of higher order elastic properties of the SiC reinforced aluminium alloys 8091 and 7064 metal-matrix composites. Ultrasonic velocities as well as their dependences on stress (acoustoelastic constants) and temperature are measured as a function of the SiC content in these composites. The results show that the second-order elastic constants, calculated from velocity measurements, increase almost linearly with the volume fraction of SiC. The acousto-elastic constants are also found to increase with increasing SiC content, but the addition of SiC has a larger effect on these constants than on the second-order elastic constants. The behavior of th e temperature dependence of ultrasonic velocities, however, is different in the two aluminium composites. (IZFP)