SUPERPLASTICITY IN A 17-VOL-PERCENT SIC PARTICULATE-REINFORCED ZK60A MAGNESIUM COMPOSITE (ZK60 SIC/17P)/

The superplastic characteristics of a 17 vol.% SiC particulate-reinfor ced ZK60A magnesium composite (ZK60/SiC/17p) have been studied. The co mposite has a fine microstructure (grain size similar to 0.5 mu m) and is stable at high temperatures. As a result of the fine microstructur e, the composite exhibits superplasticity (with an elongation to failu re of 350%) at very high strain rate (similar to 1 s(-1)). The superpl astic properties of the composite, including elongation, strain rate s ensitivity, activation energy, grain size dependence, and cavitation, were all characterized. From experimental results, i.e., the strain ra te sensitivity value, the grain size dependence of strain rate, and th e activation energy, the operative superplastic deformation mechanism in ZK60/SiC/17p is proposed. A comparison between the superplastic beh avior of the composite and that of magnesium alloys, and particularly the unreinforced magnesium alloy counterpart of the composite, has als o been made.