Production of highly perfect copper crystals with thermal cyclic annealing

Abstract Dislocation behavior in copper crystals in the course of annealing was studied, using an etch pit technique. Two annealing methods used were as follows: (1) isothermal annealing and (2) thermal cyclic annealing in which the temperature was changed between 1050° and 850°C with a period of 30 min. In the isothermal annealing, some of the isolated dislocations formed new sub-boundaries, without much reduction in the total number of dislocations. On the other hand, the thermal cyclic annealing was recognized to be conspicuously effective not only in the reduction of dislocations without forming new sub-boundaries but also in breaking-up of old sub-boundaries. With this thermal cyclic annealing highly perfect copper crystals were produced from crystals with initial dislocation densities as much as 1 × 10 6 /cm 2 .