STRUCTURE AND STRENGTH OF SUBMICROMETER-GRAINED COPPER

Samples of pure copper with submicrometer-grained microstructures have been produced by severe plastic deformation and annealed at temperatu res from 373 to 493 K. Annealing up to 423 K does not result in grain growth and the general appearance of the structure of the annealed spe cimens as seen by TEM does not deviate from the as-deformed state. Gra in growth starts above 423 K. The internal stresses measured through t he X-ray diffraction peak widths gradually decrease at low annealing t emperatures and practically vanish at temperatures higher than 423 K. The annealing temperature dependence of macroscopic strength of the sa mples correlates with the variation of the internal stresses. Possible micromechanisms of the observed recovery of material properties are d iscussed.