为获得高强高导耐蚀铜合金接触线,以Conform态细晶铜镁合金(Cu-0.4%Mg(质量分数))为对象,研究高速旋转丝表面纳米化对其耐蚀性的影响.利用光学显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)分析试样的显微组织,并借助电化学工作站研究其电化学腐蚀行为.结果表明:伴随位错胞及孪晶的形成,铜镁合金表层晶粒细化至400 nm;表面纳米化后铜镁合金在NaOH溶液中会出现明显的活化?钝化?过钝化过程,其耐蚀性有所改善,腐蚀电流密度Jcor由5.347×10?5 A/cm2减小至1.365×10?5 A/cm2,自腐蚀电位φcor由?0.470 V提高至?0.415 V.此外,提高OH–浓度会加剧腐蚀,但延长浸泡时间有利于钝化膜的形成,降低腐蚀速率.
The electrochemical corrosion behaviours of a Conform-extruded Cu-0.4%Mg (mass fraction) alloy after surface nano-crystallization (SNC) via a high-speed rotating wire-brushing were evaluated to develop the high-strength and high conductivity anti-corrosive copper alloy for high-speed railway contact wires. The microstructures of the samples were analyzed by OM, TEM and SEM, and their electrochemical corrosion behaviors were tested by an electrochemical workstation. The results indicate that the SNC-treated surface presented obvious plastic deformation flow traces with dislocation cells and twins. The grain size of the deformed zone is about 400 nm, presenting typical nano-crystalline characteristic. The SNC-treated alloy presents the typical corrosion period of active, passive and transpassive in NaOH solution. SNC improves the corrosion resistance of the Cu-Mg alloy, the corrosion current density (Jcor) decreases from 5.347×10?5 A/cm2to 1.365×10?5 A/cm2, and the corrosion potential (φcor) increasesfrom ?0.470 V to ?0.415 V. In addition, the rate of corrosion increases in higher concentration of OH–, whereas decreases with the extension of soaking time due to the formation of the passive film.
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