Effect of microalloying on the properties and Cr precipitate thermal stability of Cu-Cr-Nb alloys

Abstract

The Cu-Cr-Nb alloy's high-temperature property is well known for the heat-sink application in rocket engine combustion chambers. Effects of Ti, Si, and Co microalloying elements on the microstructure and mechanical properties at high temperatures were investigated in detail. Cu-Cr-Nb alloy ingots were prepared using the atmospheric melting method and the growth rate of Cr precipitates in the studied alloys was explored. After aging at 450 °C for 60 min, the tensile strengths of Cu-2.6Cr-0.9Nb-0.15Ti (at. %) alloy were measured as follows: 468 MPa at 20 °C, 318 MPa at 400 °C, 281 MPa at 450 °C, 238 MPa at 500 °C, 187 MPa at 550 °C, and 140 MPa at 600 °C. The addition of trace Ti element effectively reduced the growth rate of Cr precipitates during high-temperature strain and contributed to the high-temperature mechanical properties. These findings are meaningful in developing high-strength Cu–Cr–Nb alloys at high temperatures.