Microstructures and Mechanical Properties of fee Pure Metals with Different Stacking Fault Energies by Equal Channel Angular Pressing

摘要

In the present work 99.98% commercial pure copper, 99.5% commercial pure nickel and 99.5% commercial pure aluminum were imposed on high strain levels of-24, ~8 and -44 by equal channel angular pressing (ECAP) via route Be, respectively. Microstructures and mechanical properties are investigated by TEM observations, tensile tests and microhardness tests. It shows that grain sizes of pure copper, pure nickel and pure aluminum has been severed refined from several tens of microns into several hundreds of nanometers after ECAP processing, however, microstructure of copper are mainly consisted of equiaxed (sub) grains with illegible grains/ (sub) grains boundaries after processed by ECAP, while it is featured as lamellar boundaries in that of pure nickel and as elongated grains in that of pure aluminum underwent a same strain level of ECAP. Results of mechanical properties show that yield strength and microhardness increase as strain increase up to a max value in copper, and then begin to decrease slightly, while mechanical properties of the other two increase as strain increases in nickel up to a strain level of-12, and as in aluminum, yield strength and microhardness increase as strain increase in a relative low strain level, and then reach an saturation value.