Abstract
Recrystallized zinc polycrystals of commercially pure grade were subjected to hydrostatic pressure of the order of thousand atm, and its effects on their structure and dislocation arrangement were studied. Etch-pitting techique was used for this purpose. Besides twinning, slip bands and dislocation multiplication, dislocation piling-up along both the grain and twin boundaries were observed. It is found that the movement of grain boundaries and twin growth are suppressed by this dislocation lining.
Implication of this microscopic change on macroscopic mechanical behavior was studied. The increase in stiffness, the reduction of stress relaxation, and the heterogeneity in hardness were observed, but no difference was seen in tensile strength and elongation. The increase in tensile strength and elongation, which was seen when the test was performed under the confining pressure, was also seen when the specimen was pressure-treated after it had been severely twinned.
