Perfection of copper-aluminum dilute alloy single crystals grown by the Bridgman method

Abstract

The distribution and density of dislocations in 99.998% pure Cu, 0.05 and 0.10 at% Al-Cu crystals grown from the melt without cellular segregation were studied by an etch pit technique. The results obtained are as follows: (1) In pure Cu crystals, randomly distributed dislocations and subboundaries were formed. (2) In 0.05 at% Al-Cu crystals, no subboundaries were formed but many rosette patterns were observed. (3) In 0.10 at% Al-Cu crystals, some dislocation clusters were produced in addition to random dislocations, rosette patterns and subboundaries. (4) The rosette patterns and the dislocation clusters inherent in as-grown alloy crystals disappeared after thermal cyclic annealing. It is shown that these results are consistent with the concept of dislocation nucleation by impurity particles.