HIGH STRAIN RATE SUPERPLASTICITY IN A SPRAY-CAST ALUMINUM ALLOY PROCESSED BY EQUAL-CHANNEL ANGULAR PRESSING

摘要

A spray-cast aluminum 7034 alloy, containing 11.5% Zn, 2.5% Mg, 0.9% Cu and 0.20% Zr, was processed by Equal-Channel Angular Pressing (ECAP) at 473 K to produce an ultrafme grain size of ～0.3 μm The mechanical properties of the alloy were investigated using tensile testing at high temperatures over a range of strain rates. The results show that the as-pressed alloy yields superplastic elongations of >1000% when testing at a temperature of 673 K with strain rates at and above ～10~(-2) s~(-1) . The strain rate sensitivity was measured as ～0.33 thereby suggesting that dislocation glide may be an important deformation mechanism.