Plastic deformation strongly affects the microstructure of materials. Severe plastic deformation (SPD) leads to the formation of sub-micron and nano-grain structures, which often show a high strength at room temperature. One of the methods that can be used for inducing SPD is hydrostatic extrusion.
The aim of the present study is to examine how different SPD methods, including hydrostatic extrusion alters the microstructure and properties of various metals with different from one another in the Stacking Fault Energy, such as copper and aluminium.
The mechanical properties of the SPD materials were examined in a static tensile test. The results show significant increase in tensile strength and the yield stress. These effects were more marked in Cu. At same time microstructures of the extruded samples exibit very similar structure, consisting of equiaxial dislocation cells, with the average dimension of about 200 nm and very distinct, thin microbands of a large misorientation with respect to the surrounding material. The microbands in copper are of nanometric width.