Recrystallization in high purity polycrystalline magnesium during cold rolling

High purity magnesium thin films with about 200 to 500 pin in thickness prepared by a vapor deposition technique have showed a superior deformability in cold rolling at room temperature. About 80% in accumulated reduction rate was achieved without cracking by multi-pass rolling with about 5% reduction in each pass. Moreover. transmission electron microscopy showed that recrystallization occurred in the specimen cold-rolled at 80% remaining a small area of deformed region. Even when the specimen was cooled by dipping into liquid nitrogen and then immediately cold-rolled, only small edge cracks were observed at 80% reduction. and recrystallization occurred. Burgers vector analyses of dislocations in the deformed region showed that non-basal slip systems were active. Concentration of the main impurity element in the specimen, Zn, was about 3.7 atomic ppm, and those for other impurity elements, Al, Si, Mn, Cu, Ni and Fe, were less than 1 atomic ppm. Ultra low concentrations of impurities would improve the deformability and recrystallization in magnesium.