Correlation between microstructures and mechanical properties of cryorolled CuNiSi alloys with Cr and Zr alloying

Journal Article · Mon Oct 15 00:00:00 EDT 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.08.003· OSTI ID:22805814

Wang, Wei; Guo, Enyu; Chen, Zongning; Kang, Huijun ^[1]; Chen, Zhongjun ^[2]; Zou, Cunlei; Li, Rengeng; Yin, Guomao; Wang, Tongmin ^[1]

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1. Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)
2. Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100043 (China)

Highlights: • Annihilation of dislocations was suppressed by Cr alloying to CuNiSi alloys. • Cr alloying to CuNiSi alloys hinders the kinetics and refines precipitates. • Zr alloying to CuNiSi alloys promotes the growth and kinetics of precipitates. • The mechanical properties were quantitatively related to the microstructures. - Abstract: Due to their high strength and high electrical conductivity, CuNiSi system alloys are widely used as lead frames and connectors. In this work, CuNiSi alloys alloyed with Cr and Zr were rolled at liquid nitrogen temperature and subjected to various aging treatments. High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) analysis showed that in addition to forming Cr{sub 3}Si and Ni{sub 2}SiZr particles, elemental Cr and Zr distributed evenly in the matrix. Ni and Si segregated at the interface between the particles and matrix to form Ni{sub 2}Si precipitates. During the aging process, Cr alloying increased the hardness while slightly reducing the electrical conductivity of the alloy. This was ascribed to the refined precipitates and hindered precipitation kinetics. Zr alloying promoted both the precipitate growth and the precipitation kinetics of the CuNiSi alloys, while decreasing their hardness and enhancing their electrical conductivity. According to the results of the synchrotron X-ray diffraction (XRD) analysis, Cr alloying increased the dislocation density of CuNiSi alloys and suppressed the annihilation of dislocations during aging. This promoted strength through work hardening. Compared to CuNiSi alloys aged at 723 K for 2 h, the ultimate tensile strength of the alloys obtained after Cr alloying using a two-step rolling aging process was increased by 154 MPa and their electrical conductivity was increased by 4.8% International Annealed Copper Standard (IACS).

• OSTI ID: 22805814
• Journal Information: Materials Characterization, Vol. 144; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOY SYSTEMS
ANNEALING
ANNIHILATION
CHROMIUM COMPOUNDS
COPPER COMPOUNDS
DISLOCATIONS
ELECTRIC CONDUCTIVITY
INTERFACES
MICROSTRUCTURE
NICKEL COMPOUNDS
PRECIPITATION
SILICON COMPOUNDS
STRAIN HARDENING
TENSILE PROPERTIES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ZIRCONIUM COMPOUNDS