表面納米化對銅鎂合金電化學(xué)腐蝕行為的影響

表面納米化對銅鎂合金電化學(xué)腐蝕行為的影響Effect of surface nanocrystallization on electrochemical corrosion behaviours of Cu-Mg alloy

為獲得高強(qiáng)高導(dǎo)耐蝕銅合金接觸線，以Conform態(tài)細(xì)晶銅鎂合金(Cu-0.4%Mg(質(zhì)量分?jǐn)?shù)))為對象，研究高速旋轉(zhuǎn)絲表面納米化對其耐蝕性的影響。利用光學(xué)顯微鏡(OM)、透射電鏡(TEM)、掃描電鏡(SEM)分析試樣的顯微組織，并借助電化學(xué)工作站研究其電化學(xué)腐蝕行為。結(jié)果表明：伴隨位錯胞及孿晶的形成，銅鎂合金表層晶粒細(xì)化至400 nm；表面納米化后銅鎂合金在NaOH溶液中會出現(xiàn)明顯的活化-鈍化-過鈍化過程，其耐蝕性有所改善，腐蝕電流密度Jcorr由5.347×10-5 A/cm2減小至1.365×10-5 A/cm2，自腐蝕電位φcorr由-0.470 V提高至-0.415 V。此外，提高OH–濃度會加劇腐蝕，但延長浸泡時間有利于鈍化膜的形成，降低腐蝕速率。

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 (Jcorr) decreases from 5.347×10-5 A/cm2 to 1.365×10-5 A/cm2, and the corrosion potential (φcorr) increases from -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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