Yuji Imashimizu

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.

Formation of slip dislocations during Czochralski growth of copper and its dilute alloys crystals

Single crystals of pure (99.996%) Cu and its dilute alloys containing 0.05–0.5 at % Ni, 0.05–0.5 at % Al and 0.01–0.2 at % Au were grown with [111] orientation by the Czoehralski method, and the dislocation distribution patterns on the transverse (111) cross sections were examined by an etching technique. In Cu crystals, a slip pattern composed of linear arrays of dislocation etch pits was frequently revealed. The formation of the slip patterns was more pronounced in the alloy crystals with 0.05–0.1 at % Ni than in the Cu crystal. On the contrary, the slip pattern was scarcely observed in the alloy crystals with 0.05–0.5 at % Al and 0.03–0.05 at % Au. These findings indicate that the lattice hardening mechanism is not sufficient to explain the formation of the slip patterns in copper dilute alloy crystals.