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论文类型：期刊论文

发表时间：2018-10-01

发表刊物：MATERIALS CHARACTERIZATION

收录刊物：SCIE

卷号：144

页面范围：532-546

ISSN号：1044-5803

关键字：CuNiSi alloy; Cryorolling; Precipitation; X-ray diffraction; Microstructures

摘要：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 Cr3Si and Ni2SiZr particles, elemental Cr and Zr distributed evenly in the matrix. Ni and Si segregated at the interface between the particles and matrix to form Ni2Si 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).