Influence of stacking fault energy and temperature on microstructures and mechanical properties of fcc pure metals processed by equal-channel angular pressing

Abstract

Three fcc pure metals–Cu, Ni, and Al, with the same purity level (~99.99wt%) and different stacking fault energies (SFEs, about 45mJ/m2, 125mJ/m2, and 166mJ/m2, respectively) are processed by equal-channel angular pressing (ECAP) at different temperatures (room temperature, 0.32Tm, and 0.4Tm). A dislocation density-based model is improved by introducing a material-dependent parameter, and the improved model is utilized to predict the evolution of dislocation density, grain size, and strength of materials processed by ECAP processing. The predicted dislocation density, grain size, and strength are compared with the experimental results, with satisfactory agreement. The influence of the SFE on the steady-state grain size ds is discussed, based on the experimental and modeling results. It is demonstrated that at the same homologous temperatures, the dependence of the ds on the SFE exists, and that a reduction in the SFE leads to a decrease in the ds, in case there is no recrystallization in the samples. In addition, increasing deformation temperature leads to a decrease in the dislocation densities and an increase in the steady-state grain size ds. The predicted values of the ds match well with the experimental results at lower homologous temperatures.