High-Strain-Rate Deformation of FCC Metals and Alloys

The effect of strain rate, and particularly of high strain rates, on deformation mechanisms in materials is of fundamental interest to those who model and analyze loading. In many materials the strain rate sensitivity is known to increase dramatically when the strain rate is raised above 1000 s-1. This increase has been interpreted previously as a transition in deformation mechanism from thermal activation control at low strain rate to dislocation drag control at high strain rate. In copper, copper-aluminum alloys and stainless steel, recent measurements have shown that the increased rate sensitivity found at high strain rates is not due to a transition in deformation mechanisms but rather can be explained with standard thermal activation theory. These findings and their implications regarding the formulation of constitutive behavior are presented.