Microstructure of directionally solidified Cu-Cr composites

摘要

Cu-Cr composites were prepared by self-made directional solidification equipment with the high temperature gradient and double-zone heating. The microstructural evolution was investigated during the directional solidification with the different solidification rate for Cu-1.0 percent Cr, Cu-1.7 percent Cr and Cu-5.6 percent Cr alloys, respectively. It is shown that for the hypoeutectic Cu-1.0 percent Cr alloy, the general microstructures consist of primary alpha(Cu) phase and the rod-like or needle-like (alpha+beta) eutectics, and for the hypereutectic Cu-1.7 percent Cr and Cu-5.6 percent Cr alloys, alpha(Cu) phase, primary beta(Cr) phase and (alpha+beta) eutectics coexist. With the increase of the solidification rate, the morphology evolution of every phase is that, 1st cellular(dendrite) of alpha(Cu) phase thins and cellular(dendrite) spacing shortens gradually, (alpha+beta) eutectics set in alpha (Cu) cellular or dendrite, and primary beta(Cr) phase distributes unevenly on alpha (Cu) matrix, whose morphology undergoes the change from dendrite to particle.