Meng Xianghao, Xie Guoliang, Xue Wenli, Fu Yilei, Wang Rui, Liu Xinhua
Key Laboratory for Advanced Materials Processing (MOE), Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China.
Beijing Laboratory of Metallic Materials and Processing for Modern Transportation, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China.
Materials (Basel). 2022 Jun 27;15(13):4521. doi: 10.3390/ma15134521.
A Cu-Ni-Si alloy containing (Ni + Si) ≥ 5 wt.%, with the addition of Cr, is fabricated by HCCM continuous casting and two steps of aging treatment. The evolution of the microstructures and precipitations, as well as the effect of Cr atoms, is studied in this paper. An excellent combination of mechanical property (hardness HV 250-270) and electrical conductivity (46-47 %IACS) is obtained by the first step aging at 500 °C for 0.25 h and the second step aging at 450 °C for 1 h. The cold rolling and aging process are directly conducted on the solution treated specimens fabricated by HCCM continuous casting process without hot deformation, since the excellent homogeneity of matrix is obtained by solution treatment with δ-NiSi precipitates dissolved. It is found that the formation of discontinuous precipitation is suppressed by the formation of CrSi cores of 5-10 nm before the formation δ-NiSi. Then, the nucleation and growth of δ-NiSi precipitates occurs around the boundaries of these CrSi cores, leading to an enhanced nucleation rate. This study provides a promising direction for the design and optimization of Cu-Ni-Si alloys based on the further understanding of the effect of the addition of Cr.
一种（Ni + Si）≥5 wt.% 且添加了Cr的Cu-Ni-Si合金通过水平连铸（HCCM）和两步时效处理制备而成。本文研究了其微观结构和析出物的演变以及Cr原子的作用。通过在500 °C下进行0.25 h的第一步时效处理和在450 °C下进行1 h的第二步时效处理，获得了机械性能（硬度HV 250 - 270）和电导率（46 - 47 %IACS）的优异组合。由于通过溶解δ-NiSi析出物的固溶处理获得了优异的基体均匀性，因此冷轧和时效过程直接在通过HCCM连铸工艺制备的固溶处理试样上进行，无需热变形。研究发现，在δ-NiSi形成之前，5 - 10 nm的CrSi核心的形成抑制了不连续析出的形成。然后，δ-NiSi析出物在这些CrSi核心的边界周围形核并生长，导致形核率提高。基于对Cr添加作用的进一步理解，本研究为Cu-Ni-Si合金的设计和优化提供了一个有前景的方向。
