Enhanced high-temperature mechanical properties of the Cu–1.16Ni–0.36Cr alloy owing to interactions between metastable precipitates and dislocations

Abstract

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%.

Keywords

• Cu–1.16Ni–0.36Cr
• High-temperature mechanical properties
• High-temperature tensile test
• Metastable precipitates