The interaction of dislocations with coherent cobalt particles in a copper matrix

Abstract

Single crystals of copper oriented for single glide, and containing coherent precipitates of cobalt, were deformed in tension into stage I, and the dislocation distributions were determined by transmission electron microscopy of sections cut parallel to the primary glide plane. It was found that coherent particles with a radius of 120 Å remained coherent after deformation and were sheared with the matrix. However particles with a radius of 170 Å and above, spontaneously lost coherency on deformation and in some cases dislocations were found to have by-passed the precipitate by cross-slip, resulting in rows of prismatic loops of primary Burgers vector. These results are at variance with the conclusions of Gleiter, (1) but it is shown that his results are more consistent with the above interactions than with the mechanism which he proposes.