Non-destructive microstructural characterization of aluminium matrix composites by ultrasonic techniques

In this study, an attempt was made to correlate the propagation of ultrasonic waves to various microstructural features in Al–SiC composites. The investigated parameters include the volume fraction, size, and distribution of the SiC-reinforcing particulate. Composites were fabricated by hot pressing of Al, Cu, and SiC powders. It has been shown that the ultrasonic velocity in all composites increased with an increase in SiC content. At identical volume fraction, changing the size of SiC particles did not affect the velocity. However, a segregation of SiC particles along the grain boundaries caused a decrease in ultrasonic velocity, which was attributed to the higher amount of residual porosity in segregated structures.