Precipitation behavior of Cu-3.0Ni-0.72Si alloy

Yi, Jiang, Jia, Yanlin, Zhao, Yuyuan ORCID: 0000-0003-2356-8435, Xiao, Zhu, He, Kejian, Wang, Qi, Wang, Mingpu and Li, Zhou
(2019) Precipitation behavior of Cu-3.0Ni-0.72Si alloy. ACTA MATERIALIA, 166. pp. 261-270.

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Cu–Ni–Si alloys have been widely applied in electronic and electrical industries. The precipitation behavior of some of the Cu–Ni–Si alloys is still not well understood. In this study, the precipitation behavior of the Cu-3.0Ni-0.72Si alloy aged at 600 °C for different times was investigated by transmission electron microscopy, atom probe tomography and phenomenological theory of precipitation crystallography. A new orientation relationship (OR) between the precipitates and the Cu matrix was found in the over-aged condition and a coarsening mechanism of the metastable precipitates was put forward. The two- and three-dimension invariant line theories were successfully applied in interpreting the evolution of the ORs and the morphologies in the Cu/δ-Ni 2 Si (Cu/δ) system. At the early stage of aging, the fine metastable δ’-(Cu, Ni) 2 Si precipitates are coherent with the Cu matrix, with a quasi-Bain OR of (110) Cu ||(100) δ′ and [001] Cu ||[001] δ′ , and four pairs of parallel conjugate planes: (1¯1¯1) Cu ||(3¯01) δ′ , (111) Cu ||(301) δ′ , (1¯11) Cu ||(021) δ′ , and (11¯1) Cu ||(02¯1) δ’ . The precipitates have a δ-Ni 2 Si structure, with some Ni atoms substituted by Cu atoms. During growth, the core region of the metastable δ’-(Cu,Ni) 2 Si precipitate transforms into stable δ-Ni 2 Si, with a quasi-NW OR of (1¯11) Cu ||(021) δ and [110] Cu ||[100] δ , while a layer of metastable δ’- (Cu, Ni) 2 Si still exists around the core. With prolonging aging time, the δ-Ni 2 Si precipitates with the OR of (1¯11) Cu ||(021) δ and [110] Cu ||[100] δ grow two-dimensionally to form a plate-like shape, while those with the OR of (111) Cu ||(301) δ and [1¯10] Cu ||[010] δ grow one-dimensionally to form a fiber-like shape.

Item Type: Article
Uncontrolled Keywords: Cu-Ni-Si alloy, Precipitation, Orientation relationship, Precipitate morphology, Invariant line theory
Depositing User: Symplectic Admin
Date Deposited: 04 Feb 2019 09:06
Last Modified: 19 Jan 2023 01:05
DOI: 10.1016/j.actamat.2018.12.047
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