Abstract
The recrystallization temperature of refined high purity zinc (zone-refined from 99.999 pct distillated zinc) after rolling reduction, has been examined by means of X-ray analysis and of microscopic study, with three kinds of pure zinc of purities of 99.1, 99.98, 99.999 pct as controls. Hardness tests were made on these specimens cold-rolled and annealed. These hardness curves were found to show some different aspects from the ordinary curves taken on metals or alloys, cold-rolled in various degrees and then annealed at various temperatures. From such results it has been concluded that the recrystallization temperature cannot be exactly determined from these hardness-annealing curves. It was ascertained by means of X-ray analysis using low temperature camera that the recrystallization of high purity zinc began at lower temperature than that of low purity one, and that such super-purity zinc as was zone-refined from 99.999 pct distillated zinc would begin to recrystallize for 1 hr by keeping for 1 hr at about −70°C after 50 pct cold rolling, and complete at −70°C after 90 pct cold rolling, after storaging in dry ice and aceton solution at −78°C.
