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Indexed by:期刊论文

Date of Publication:2019-01-07

Journal:MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Included Journals:SCIE、Scopus

Volume:740

Page Number:165-173

ISSN No.:0921-5093

Key Words:Cu-Cr-Co-Si alloys; Cryogenic rolling; Structure; Hardness; Strength; Electrical conductivity

Abstract:Cu-Cr alloys have been widely used in industrial applications owing to their good combination of mechanical properties and electrical conductivity. However, the comprehensive performance of the alloy needs to be further improved to meet the harsh working environment. Hence, in this study, a new type of Cu-Cr alloy with Co and Si additions together with cryogenic rolling (CR) was designed and investigated. Microstructure analysis confirms that the Cr15Co9Si6 and Co2Si phases are formed with Co and Si additions into the Cu-Cr alloy. For the more, partial Cr15Co9Si6 phase decomposes during heat treatment process, and the Co2Si and Cr precipitates are precipitated from matrix during aging process. The improvement of tensile properties of the Cu-1Cr-1Co-0.6Si alloy is mainly attributed to the precipitation strengthening and grain boundary strengthening, and is also benefited from dislocation density strengthening, twin boundary strengthening, and solid solution strengthening. The electrical conductivity of the Cu-1Cr-1Co-0.6Si alloy decreases dramatically mainly due to the increase of impurity scattering caused by surplus Si atoms. CR deformation is helpful for more solute atoms precipitated from the supersaturated solid solution during aging process, and thus the electrical conductivity of the Cu-1Cr-1Co-0.6Si alloy increases with increasing deformation amount. After homogenizing treatment at 900 degrees C for 2 h, hot rolling by 60% at 900 degrees C, solution treating at 990 degrees C for 4 h, cold rolling by 90%, and aging at 440 degrees C for 1 h, the hardness, yield strength (YS), ultimate tensile strength (UTS), and electrical conductivity of the Cu-1Cr-1Co-0.6Si alloy are 214.6 HV, 663.7 MPa, 745.9 MPa and 41.6%IACS, respectively, which exhibit good mechanical properties with a proper electrical conductivity. These results provide a feasible route for developing high performance Cu-Cr alloys.