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Indexed by:期刊论文

Date of Publication:2019-02-01

Journal:MATERIALS CHEMISTRY AND PHYSICS

Included Journals:SCIE、EI

Volume:223

Page Number:486-493

ISSN No.:0254-0584

Key Words:Copper alloy; Spinodal decomposition; Strengthening; Mismatch

Abstract:Cu-Ni-Cr alloys have a typical spinodal decomposition structure. However, a systematic investigation of the correlation between the mismatch of the two decomposition phases, Cu-rich (gamma(1)) and Ni-rich (gamma(2)), and the gamma 2 morphology is lacking. In this study, the microstructure evolution of Cux[Ni3Crl] (x = 1, 2, 3, 4, 5, 7, 9, and 12) alloys was investigated over a wide composition range. The results show that mismatch significantly affects the shape of the gamma(2) precipitates. The gamma(2) phase is cubic when the mismatch degree (eta) is in the range 0.62%-0.75% and lath-shaped when eta is in the range 1.08%-1.35%. With increasing Cu content, the proportion of the lath-shaped gamma(2) phase decreases and that of the cubic gamma(2) phase continuously increases. Cubic precipitates enhance the alloy strength, while lath-shaped precipitates show better corrosion resistance owing to their high packing density. Therefore, an appropriate x can be chosen according to the actual service conditions. In addition, the Cr state affects the microstructure and performance of the alloys. Cr in the solid solution state promotes spinodal decomposition, while a large amount of Cr-rich precipitates at the grain boundaries has a negative effect on the mechanical performance.