Structure and properties of heavily cold-worked fcc metals and alloys

Abstract

Al-5%Mg, Ag, Au, Cu-l0%Ni, and Ni in the form of bars have been deformed to large strains by rolling at 20°C, and their microstructures determined by thinfoil transmission electron microscopy. Tensile tests have been carried out on the rolled specimens, and from the results obtained stress/true rolling strain curves have been obtained. It has been found that over a wide range of strains there are linear relationships between stress and true rolling strain; i.e. there is a work-hardening modulus. The workhardening modulus has been found to be related to the homologous temperature of deformation and the stacking fault energy. High moduli are found when plastic deformation gives rise to an increase in the dislocation density. Low moduli are found when shear bands consisting of small highly misorientated grains seem to form as a result of a structural instability within regions of high dislocation density.