Abstract
Achieving a good match between strength and conductivity is a challenge of the development of the high-performance Cu-Cr-Nb alloy for aerospace and fusion energy. The effect of heat treatment on Cr2Nb phase, strength and conductivity of spark plasma sintered (SPSed) Cu-2Cr-1Nb (at%) alloy was investigated. The results illustrated that Cr2Nb phase of Cu-2Cr-1Nb alloy can be regulated by heat treatment, multi-scale Cr2Nb phase with sizes of 0.10–0.50 μm, 30–100 nm and less than 30 nm was obtained, and the strength and conductivity were significantly increased after heat treatment at 500 °C for 2 h, the room temperature tensile strength and conductivity were 332 MPa and 86.7% IACS, 2.5% and 34.8% higher than those of as-SPSed alloy; the tensile strength at 700 °C was 76 MPa. Increasing heat treatment temperature and time, the tensile strength of the alloy was reduced by 1.5%, 4.3% and 12.3% after heat treatment at 500 °C, 700 °C and 950 °C for 72 h. The good match between strength and conductivity of Cu-Cr-Nb alloy was obtained by reducing the content of alloying elements (Cr and Nb) and microstructure regulation. This approach can be used to prepare structural/functional materials with excellent strength and conductivity.
Highlights
High-strength and high-conductivity copper alloy is one of the key structural/functional materials used in many high-tech fields, such as aerospace, energy and so on [1,2]
For high-heat-flux structural and functional materials in aerospace and fusion energy, there are high requirements for thermal stability, in addition to strength and conductivity; the applications of many high-strength and high-conductivity copper alloys are limited due to their poor microstructural stability and the over-coarsening of second phase at high temperature
The Cu-2Cr-1Nb alloy was fabricated by a spark plasma sintering (SPS) system (HPD25-3, FCT, Rauenstein, Germany) using close-coupled argon atomized powder [40,41]; the composition of powder is shown in Table 1, and the particle size of powder was below 100 mesh (150 μm)
Summary
High-strength and high-conductivity copper alloy is one of the key structural/functional materials used in many high-tech fields, such as aerospace, energy and so on [1,2]. Cu-Cr-Nb alloy exhibits superior comprehensive properties, such as strength, creep, fatigue, conductivity and microstructural stability, and is one of the most excellent high-heat-flux structural materials for aerospace and fusion energy [1,17,18,19,20,21,22,23]. How to effectively regulate microstructure of Cu-Cr-Nb alloy, especially the size of Cr2 Nb phase, and realize the good match of strength and conductivity, is still the key problem to be solved in the development of high-performance Cu-Cr-Nb alloys. A Cu-2Cr-1Nb (at%) alloy was fabricated by SPS with close-coupled argon gas atomized alloy powder [40,41], the size of Cr2 Nb phase decreased obviously, but the strength and conductivity still had room for improvement. This approach has a great significance for the development of high-performance Cu-Cr-Nb alloys
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