Ameliorating the microstructure and properties of a Cu-Cr alloy by introducing a high-temperature short-time treatment into the thermo-mechanical process

The optimization of process is essential for improving the overall properties of high-strength and high- conductivity Cu alloys. This study introduces a high-temperature short-time treatment (HTSTT, 850 degrees C/5 min) into the thermo-mechanical process of a Cu-Cr - Cr alloy. Following the process of "solid solution- cold rolling- HTSTT- cold rolling- aging", the tensile strength of the alloy increases from 450 MPa to 508 MPa, with the electrical conductivity increasing from 82.2 %IACS to 86.4 %IACS when compared to the conventional process of "solid solution- cold rolling- aging" under the same total deformation condition. The reasons for the improvement in the comprehensive properties of the alloy after introducing HTSTT are analyzed through microstructural characterization. The results indicate that the HTSTT promotes the occurrence of recrystallization, leading to grain refinement, which results in smaller grain sizes during subsequent processing. Additionally, the introduction of HTSTT changes the main texture of the alloy from (100)//X to (111)//X during the process, which is beneficial to enhancing the alloy's strength and electrical conductivity. More importantly, the HTSTT facilitates the precipitation of solute Cr atoms, leading to the formation of a significant quantity of nanoscale Cr particles, most of which are spherical with an average size of 27 nm. During the subsequent cold rolling process, these Cr particles effectively pin dislocations and promote their proliferation, leading to the precipitation of a large number of smaller Cr particles during the aging process, with an average size of 4.8 nm. These finer Cr particles are crucial for precipitation strengthening. This paper offers valuable insights into the microstructural optimization and performance enhancement of high-strength and high-conductivity Cu alloys.