polarizaton data.dat from Effect of Ag alloying and trace precipitation on corrosion resistance of Ti-Ta-Ag ternary alloy

This work systematically analysed the electrochemical and corrosion behaviour of Ti-Ta-Ag ternary alloy samples in Hank's solution. For the samples with 1.5% and 3% Ag content, the sintering temperature increased from 750 to 950°C, and the corresponding corrosion resistance increased by 100 times due to the increased alloying of Ag; meanwhile for the sample with 4.5% Ag content, the sintering temperature increased from 750 to 950°C, and the corresponding corrosion resistance decreased by six times due to the increased precipitation of Ag. These tests prove that the Ag alloying is beneficial to the enhancement of the corrosion resistance of Ti-Ta-Ag ternary alloy, but the Ag trace precipitation has the opposite effect. A series of electrochemical characterizations and density functional theory calculations explain the mechanism of the above phenomenon. Ag alloying can promote the formation of uniform, complete, dense, stable and thick passivation layer on the surface of Ti-Ta-Ag ternary alloy, which makes Ti-Ta-Ag ternary alloy uniformly corroded without pitting. In addition, Ag alloying can effectively reduce the contact resistance of the solid–liquid interface. However, the trace precipitation of Ag plays the opposite role to the above effect.

本研究系统分析了钛-钽-银（Ti-Ta-Ag）三元合金试样在汉克溶液（Hank's solution）中的电化学行为与腐蚀行为。对于银（Ag）含量为1.5%与3%的试样，当烧结温度从750℃提升至950℃时，随着银的合金化程度提升，其耐腐蚀性能提升了100倍；而对于银含量为4.5%的试样，当烧结温度从750℃提升至950℃时，由于银的析出量增加，其耐腐蚀性能反而下降了6倍。上述实验结果证实，银的合金化有助于提升钛-钽-银三元合金的耐腐蚀性能，但银的微量析出则会产生相反效果。本研究通过一系列电化学表征与密度泛函理论（Density Functional Theory, DFT）计算，阐释了上述现象的作用机制：银的合金化可促进钛-钽-银三元合金表面形成均匀、完整、致密、稳定且厚实的钝化膜，使该合金呈现均匀腐蚀而非点蚀；此外，银的合金化还可有效降低固-液界面的接触电阻。然而，银的微量析出则会产生与上述效应完全相反的作用。