Thermal stability of submicron grained copper and nickel

The features of structure and thermal stability of submicron grained copper and nickel processed by severe plastic deformation are considered. The results of studies by various techniques: transmission electron microscopy, X-ray diffraction, differential scanning calorimetry, electrical resistance and microhardness are presented. The investigations have shown that thermal stability of submicron grained materials is determined not only by a mean grain size but also by the density and distribution of the grain boundary dislocations. The relaxation of the grain boundary dislocations precedes the grain growth starting at 175°C and influences on thermal stability.