Thermal structure changes in copper and nickel processed by severe plastic deformation

The results of thermal structure evolution studies of ultrafine grained copper and nickel by transmission electron microscopy, X-ray diffraction, DSC, electrical resistance and microhardness are presented. The investigations have shown that the heat release, the recovery of electrical resistance, the relaxation of elastic strains precede the grain growth starting above 175 °C. Different techniques have shown that thermal stability of ultrafine grained structure is associated not only with grain growth but also with the relaxation of the grain boundary structure.