Effect of high temperature-high pressure treatment on microstructure and mechanical properties of Cu-Cr alloy

Abstract

The microstructure of the Cu-Cr alloy prepared by infiltration before and after different pressures treatment at 900°C for 10 min was observed by metallographic microscope, scanning electron microscope (SEM), and transmission electron microscopy (TEM). And the mechanical properties were measured by nanoindenter, hardness tester and tensile testing machine. According to the experimental results, the effects of high pressure treatment on the mechanical properties were discussed. The results showed that the hardness of Cu matrix and Cr phase were 114Hv and 194Hv under the pressure of 3 GPa, which were 18.75% and 10.23% higher than those of the infiltrated alloy. Also, the hardness and compression yield strength of Cu-Cr alloy were 134 HB and 241 MPa after 3 GPa pressure treatment, respectively, 11.67%, 19.31% higher than those of the infiltrated alloy. On the basis of analysis, the high pressure treatment can improve the compactness of Cu-Cr alloys, promote the precipitation of nanometer Cr particles and increase the hardness and elastic modulus of Cu matrix and Cr phase, resulting in the improvement of hardness and compression yield strength in Cu-Cr alloys. In the range of 1∼6 GPa, the hardness and compression yield strength of alloys increase with the increase of pressure. However, these mechanical properties of Cu-Cr alloy increases slowly when the pressure exceeds 1 GPa.