Crystals of dilute alloys, having a [111] orientation, were pulled from melts which contained 0.02, 0.05, 0.1, 0.2 or 0.5at%Ni, by using the Czochralski method. The distributions and densities of grown-in dislocations were examined by etching the (111) faces of 6 transverse cross-sections. Linear arrays of slip dislocations, along <1¯10> directions, predominated in 0.02, 0.05 and 0.1at%Ni crystals. The mean dislocation densities in those crystals became higher than those in Cu crystals. In the case of 0.2at%Ni crystals, an inhomogeneous sub-structure which consisted of long sub-boundaries and dislocation clusters was introduced. Slip dislocations were very uncommon, and the dislocation densities were generally high. In 0.5at%Ni crystals, short sub-boundaries and dislocation clusters were distributed quite homogeneously, and the dislocation density became higher. It was found that the effect of small additions of Ni upon the formation of slip dislocations, and upon the dislocation density, was quite different to the effect of adding Al or Au. The formation of dislocation sub-structures in crystals which contained more than 0.2at%Ni was attributed to the trapping of inclusions at a non-planar solid/liquid interface which was destabilized by constitutional supercooling.

Dislocation Formation in Czochralski Grown Copper-Nickel Dilute Alloy Crystals Y.Imashimizu, J.Watanabe: Journal of the Japan Institute of Metals, 1998, 62[6], 497-504