Strain rate and temperature effects on mechanical response of polycrystalline high purity aluminum under dynamic shear deformation

This paper aims at studying the effects of strain rate and temperature on the mechanical behaviour of polycrystalline high purity aluminum deformed in shear. The specimens are deformed at constant strain rate in the range from γ = 6 × 10^-4 s^-1 to 4.2 × 10³ s^-1 and at constant temperatures ranging from 80°K to 323°K. In addition, in order to investigate the effect of material's sensitivity on deformation history, a sharp increment in strain rate is imposed in jump tests during the quasi-static straining; the material is also deformed at different temperatures after being prestrained at room temperature. The results indicate that the deformation mechanisms change in the neighborhood of γ = 10³ s^-1, and that three regions of temperature dependence are found to be below 130°K, to be from 130°K to 220°K, and to be above 220°K. The validity of descriptions of results based on a power law τ = Kγ^m are investigated.