1992 Volume 42 Issue 10 Pages 561-567
An aluminum alloy composite (MA7075+10SiC alloy) has been developed to show high strain rate superplasticity in tension and compression test. Fibers of 7075-0.3 mass%Zr alloy made by a metal cutting chatter technique were mixed with SiC particles by using vibrational ball mill, compacted in nitrogen atmosphere, and then pre-strained at 793K. After the pre-straining, SiC particulates are distributed uniformly within matrix, and a fine grain structure, with average grain size of about 0.8μm is developed. In a strain rate range of 5×10-1 to 1×10s-1 at 793K, the MA7075+10SiC specimen can be compressed to about 0.65 strain without surface cracking under very low flow stress level. The observed m value is larger than 0.3. In tensile test of the MA7075+10SiC specimens warm rolled after the pre-straining, maximum elongation of about 315% is obtained at an initial strain rate of 5 s-1 at 793K. The very fine grain (or subgrain) structure of the composite material is considered to be reason of superplasticity in such a high strain rate range.
