Wang Yuxin, Cheng Guang, Tay See Leng, Guo Yunxia, Sun Xin, Gao Wei
School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu, China.
Department of Chemical & Materials Engineering, the University of Auckland, PB 92019, Auckland 1142, New Zealand.
Materials (Basel). 2017 Aug 10;10(8):932. doi: 10.3390/ma10080932.
In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of an electrodeposited nanocrystalline Ag coating. Microstructural features were investigated with transmission electron microscopy (TEM). The results indicate that the addition of Bi introduced nanometer-scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastic-plastic properties of the Ag nanocrystalline coating with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently-developed inverse method. The results indicate that the as-deposited nanocrystalline Ag coating contained high mechanical anisotropy. With the addition of 1 atomic percent (at%) Bi, the anisotropy within Ag-Bi coating was very small, and yield strength of the nanocrystalline Ag-Bi alloy in both longitudinal and transverse directions were improved by over 100% compared to that of Ag. On the other hand, the strain-hardening exponent of Ag-Bi was reduced to 0.055 from the original 0.16 of the Ag coating. Furthermore, the addition of Bi only slightly increased the electrical resistivity of the Ag-Bi coating in comparison to Ag. Results of our study indicate that Bi addition is a promising method for improving the mechanical and physical performances of Ag coating for electrical contacts.
在本研究中，我们研究了铋（Bi）的添加对电沉积纳米晶银涂层微观结构和力学性能的影响。采用透射电子显微镜（TEM）研究微观结构特征。结果表明，Bi的添加在初始银微观结构中引入了纳米级的Ag-Bi固溶体颗粒和更多内部缺陷。结合最近开发的反演方法，通过纳米压痕实验研究了添加和未添加Bi的银纳米晶涂层的各向异性弹塑性性能。结果表明，沉积态的纳米晶银涂层具有较高的力学各向异性。添加1原子百分比（at%）的Bi后，Ag-Bi涂层内的各向异性非常小，并且与Ag相比，纳米晶Ag-Bi合金在纵向和横向的屈服强度均提高了100%以上。另一方面，Ag-Bi的应变硬化指数从原始银涂层的0.16降至0.055。此外，与Ag相比，Bi的添加仅略微增加了Ag-Bi涂层的电阻率。我们的研究结果表明，添加Bi是改善用于电接触的银涂层力学和物理性能的一种有前景的方法。
