Superplasticity in an aluminum-zinc alloy

摘要

Recent investigations have demonstrated remarkable ductility in a20 weight per cent Aluminum - 80 weight per cent Zinc alloy. An understandingof the mechanisms responsible for this superplastic behaviorcould have important applications in other commercial alloy systems.This investigation consists of correlated metallographic examination,X-ray diffraction analysis, and tensile testing of Al-Zn binaryalloys of 17 per cent, 20 percent, and 23 per cent Aluminum at specificstages of treatment.Special attention is focused on the heat evolution which followsquenching, a phenomenon apparently associated with the spontaneousbreakdown of the unstable d structure. Of particular interest is theappearance of a disorganized, undefined structure after the heat evolutionas evidenced by diffraction analysis. The subsequent organizationof this structure and apparent diffusional effects as aging takes placeat room temperature is clearly indicated by experimental evidence. Thelack of three-dimensional periodicity in space following quenching fromthe single phase region suggests a strong analogy between the alloysstudied and the viscous behavior of glass- like materials.