期刊
出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2019.138390
关键词
Cu-Ni-Co-Si alloy; Precipitation evolution; Atomic distribution; Multistage thermomechanical treatment; Physical properties
类别
资金
- National Key R&D Program of China [2016YFB0301300]
- Science and Technology Service Network Initiative of China [KFJ-STS-QYZX-061]
- Natural Science Foundation of China [51601017]
An in-depth exploration of the microstructure evolution and characterization of the precipitates in a quaternary Cu-Ni-Co-Si alloy under different aging conditions was conducted. The precipitates were confirmed to be delta-(Ni, Co)(2)Si and exhibited different morphological features with high-resolution transmission electron microscopy. The three-dimensional atom probe technique revealed the quantitative atomic distribution and corresponding content changes in the precipitates. Combined with the above analysis, these results allowed the evolution of the delta-(Ni, Co)(2)Si precipitates to be determined. The precipitation phase was divided into two zones: unstable zone I at the edge and zone II comprising pure delta-(Ni, Co)(2)Si in the core. As aging progressed, the thickness of zone I decreased, and that of zone II increased continuously, accompanied by the replacement of Cu atoms in the precipitates by external Ni atoms. In the peak-aged state, the Ni, Co and Si atoms exhibited a substantial amount of cosegregation, and the corresponding atomic concentrations were 40 at.%, 25 at.% and 35 at.%, respectively. The studied alloy exhibited excellent comprehensive properties, including a hardness of 318 HV, an electrical conductivity of 37.1% IACS, a tensile strength of 1003 MPa, a yield strength of 929 MPa, and an elongation of 4.5%, after the introduction of a multistage thermomechanical treatment process. Theoretical analysis was conducted for different strengthening mechanisms, and the findings coincided well with the experimental results.
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