In this paper, a Cu-Ni-Cr alloy was prepared by adding a Ni-Cr intermediate alloy to copper. The effects of the cold rolling reduction rate on the microstructure and properties of the Cu-1.16Ni-0.36Cr alloy after thermo-mechanical treatment were studied. The results show that the tensile strength of the alloy increased while the electrical conductivity slightly decreased with an increase of the cold rolling reduction rate. At a rolling strain of 3.2, the tensile strength was 512.0 MPa and the conductivity was 45.5% IACS. At a rolling strain of 4.3, the strength further increased to 536.1 MPa and the conductivity decreased to 41.9% IACS. The grain size and dislocation density decreased with an increase of the reduction rate in the thermo-mechanical treatment. However, when the rolling strain reached 4.3, the recrystallization degree of the alloy increased due to an accumulation of the dislocation density and deformation energy, resulting in a slight increase in the grain size and a decrease in the dislocation density. The texture strength of the brass increased due to the induced shear band, with an increase of the cold rolling reduction rate. The reduction rate promoted a uniform distribution of nano-scale Cr precipitates and further enhanced the strength via precipitation strengthening.

Herein, an alloy Cu–1.16Ni–0.36Cr with outstanding high-temperature mechanical properties was obtained, and the underlying mechanism was discussed. The properties were compared with those of commercial Cu–Fe–P alloys. The alloy exhibited a high-temperature softening temperature of 674.7 °C. Tensile tests conducted at high temperatures revealed that at 700 °C, the alloy maintained a tensile strength of 131.3 MPa, whereas Cu–Fe–P alloys only exhibited a tensile strength of 58.7 MPa. Microstructural analysis revealed the formation of nanoscale Ni₃Cr₇ precipitates near fractures at high temperatures, with the average size being approximately 10 nm. These nanoscale precipitates hindered the coarsening of Cr particles and dislocation slips, forming dislocation rings and substantially enhancing the high-temperature mechanical properties of the alloy. Furthermore, the nanoscale precipitates considerably impeded the growth and expansion of recrystallized grains. After a high-temperature treatment at 700 °C, a portion of the microstructure in the alloy remained stretched, with the small-angle grain boundaries being high (68.2%) and the recrystallization degree being only 50.4%.

This study systematically investigates the influence of different heat treatment processes on the microstructural evolution and mechanical properties of Cu-15Ni-3Al alloys, with particular emphasis on the synergistic strengthening mechanisms of spinodal decomposition and precipitation hardening. Two distinct aging routes—solution aging and direct aging—were designed to facilitate a comparative assessment of microstructural characteristics and their correlation with mechanical performance. Comprehensive characterization was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and room-temperature tensile testing to elucidate the structure–property relationships. The results reveal that direct aging promotes the formation of fine, coherent L1₂-type Ni₃Al precipitates and the evolution of Ni-enriched regions initially generated through spinodal decomposition into stable Ni₃Al precipitates. These microstructural features act as effective barriers to dislocation motion, thereby significantly enhancing both strength and ductility. The findings provide valuable insights into optimizing heat treatment strategies to improve the performance of Cu-Ni-Al alloys.

In this paper, Cu-1.16Ni-0.36Cr alloy was obtained by adding Ni-Cr intermediate alloy, and the effects of aging parameters on its microstructural evolution and mechanical properties were studied. The results show that after secondary aging (solid solution + one time cold rolling at 87.5% + annealing at 300 °C for 2 h + secondary aging at 450 °C for 2 h), dispersed BCC structure Cr precipitates are obtained in the alloy, which shows good comprehensive properties (strength of 512.0 MPa, elongation of 17.2%, and electrical conductivity of 45.5%). The change in aging parameters significantly affects the existing form of Cr precipitates. When the aging temperature increases from 400 °C to 450 °C, the precipitated phase begins to have a stable boundary, which shows that the precipitated phase with BCC structure Cr precipitates (~10 nm in range). When the aging temperature further increases to 500 °C, the size of Cr precipitated phase begins to grow, from 5.0 nm to 16.7 nm. The strengthening mechanism of the alloy with different aging time at 450 °C is calculated, and the relationship among aging parameters, microstructure characteristics, strengthening mechanism and mechanical properties is established. It is concluded that precipitation strengthening and dislocation strengthening are the main strengthening mechanisms of the alloy.