<研究論文>Cu-30mass%Zn合金の高温延性に及ぼす結晶粒径とひずみ速度の影響

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Cu-30mass%Zn alloys with various grain sizes were tensile tested under vanous strainrates from 3.3xlO-5 S·l to 3.3x10-3 S-l and at temperatures from 523K to 773K. Elongation tofracture for fine-grained specimens shows high ductility and a maximum value in a range ofintermediate temperature. The peak ductility increases with increasing in strain rate though itdoes not depend on the initial grain size. Type of the flow curves is controlled by the factors oftemperature, strain rate and initial grain size. The flow curve of coase-grained specimens showsa serrated flow at lower temperatures and at higher strain rates while shows the work softeningprocesses at other conditions. The flow curve of fine-grained specimens shows a typical flowbehavior of dynamic recrystallization. It should be noted that these flow curves tend to changefrom a type having simple peak due to dynamic recrystallization to another type having multiplepeaks with decreasing initial grain size and strain rate and/or with increasing temperature.The values of stress exponent and apparent activation energy for deformation range from 3 to5 and from 120 to 135kJ/mol, respectively. The main reason for this can be explained by a factthat the both mechanisms of dislocation glide and grain boundary sliding occur simultaneously.
秋田大学の論文