Influence of strain rate & temperature on the mechanical response of ultrafine-grained Cu, Ni, AND Al-4Cu-0.5Zr

In this paper the mechanical properties of three bulk ultrafine-grained (UFG) materials produced by Equal Channel Angular Pressing (EGA) are presented. Although the influence of strain rate and temperature on the mechanical behavior of pure Cu and Ni and a variety of their alloys has been extensively studied, the effect of strain rate and temperature on nanocrystalline materials remains poorly understood. In this paper the influence of strain rate, varied between 0.001 and similar to 4500 s(-1), and temperature on the compressive mechanical behavior of UFG- Cu, Ni, and Al-4Cu-0.5Zr is shown. The temperature and strain-rate sensitivity of all three metals was found to be significantly higher than that typical for annealed FCC polycrystalline metals. The yield strength values measured for the UFG-Cu and Ni were found to lie both above those extrapolated for classical Hall-Fetch data on these materials supporting the importance of substructure, in addition to average grain size, to yield strength. (C) 1997 Acta Metallurgica Inc.