Effect of Annealing Temperature on the Recrystallization of Nickel with Different Ultradisperse Structures

Аннотация

Various structures (cellular, mixed, and submicrocrystaline) were realized in samples of single-crystal nickel (99.98 wt % purity) using shear deformation under a pressure at room temperature. The presence of microcrystallites in the nickel structure after deformation was shown to lead to the development of recrystallization during annealing in the temperature range of 250–350°C via both continuous and discontinuous mechanisms. In the case of the continuous mechanism, the microcrystallites formed during deformation are recrystallization centers; in the case of the discontinuous mechanism, the recrystallization centers are the thermoactivated nuclei formed during annealing. A nonmonotonous dependence of the average recrystallized-grain size on the heating temperature was found and causes for this dependence are discussed.