Abstract
Exper ments have been carried out to examine the effects of cold-working on the rate of precipitation in binary polycrystalline Cu-Ti, Cu-Cr and Cu-Fe alloys by measurements of electrical resistance, microhardness and thermoelectromotive force. In Cu-Ti alloys (1.72%Ti), in which the existence of the intermediate phase in precipitation process was suggested from our previous experiments, the electrical resistance measurements provided evidence that at lower aging temperature (220°) the rate of precipitation of cold-worked specimens is less than that of unworked specimen, and that at higher temperature cold working accelerates the process. In either Cu-Cr alloys (0.30%Cr) or Cu-Fe alloys (1.29%Fe), such a suppressive effect of cold-working is found at lower aging temperature, too, although not so remarkable as in the Cu-Ti alloys. On the other hand, in copper of high purity, such an effect is not found. It is suggested that the rate of precipitation at lower temperature in cold-worked specimens is retarded by the stronger binding interaction between solute atoms and lattice defects, and this interaction effect is more remarkable in the Cu-Ti alloys. These results have been confirmed by the calculations of the interaction energies between solute atoms and dislocations.
