Dynamic plastic deformation at liquid nitrogen temperature and aging effects on microstructure and properties of Cu-0.3Zr-0.15Cr alloys

The 9R phase is rarely formed in copper alloys because of its high stacking fault energy. In this study, we generated a large amount of 9R phase in Cu-0.3Zr-0.15Cr alloys by dynamic plastic deformation (DPD) at liquid nitrogen temperature for the first time, and revealed the transformation mechanism of 9R to nanotwins. The process of DPD + aging treatment enables the alloy to obtain excellent comprehensive properties (strength of 657 MPa, electrical conductivity of 75.2 % IACS, and elongation of 14.6 %), which are derived from the heterogeneous microstructure composed of ultrafine structures, coarse grains, and nano precipitated phases. In addition, we have evaluated the phase transformation kinetics after DPD at liquid nitrogen temperature. This work provides a new way to better understanding the microstructure transition and precipitation kinetics under dynamic plastic deformation with aging treatment at liquid nitrogen temperature.