摘要
The corrosion performance of high pressure die-cast Al？6Si？3Ni （SN63） and Al-6Si-3Ni-2Cu （SNC632） alloys in 3.5%（mass fraction） NaCl solution was investigated. X-ray diffraction （XRD） and microstructural studies revealed the presence of singlephase Si and binary Al3Ni/Al3Ni2 phases along the grain boundary. Besides, the single Cu phase was also identified at the grainboundaries of the SNC632 alloy. Electrochemical corrosion results revealed that, the SNC632 alloy exhibited nobler shift incorrosion potential （φcorr）, lower corrosion current density （Jcorr） and higher corrosion resistance compared to the SN63 alloy.Equivalent circuit curve fitting analysis of electrochemical impedance spectroscopy （EIS） results revealed the existence of twointerfaces between the electrolyte and substrate. The surface layer and charge transfer resistance （Rct） of the SNC632 alloy was higherthan that of the SN63 alloy. Immersion corrosion test results also confirmed the lower corrosion rate of the SNC632 alloy andsubstantiated the electrochemical corrosion results. Cu addition improved the corrosion resistance, which was mainly attributed to theabsence of secondary Cu containing intermetallic phases in the SNC632 alloy and Cu presented as single phase.
研究高压铸造Al-6Si-3Ni(SN63)及Al-6Si-3Ni-2Cu(SNC632)合金在3.5%(质量分数)NaCl水溶液中的腐蚀行为。X射线衍射及显微组织分析表明,单相Si及Al3Ni/Al3Ni2二元相分布在合金的晶界处,并且在SNC632合金晶界处析出单相Cu。电化学腐蚀实验结果表明,与SN63合金相比,SNC632合金表现出高的腐蚀电位(φcorr),低的腐蚀电流密度(Jcorr)及高的耐腐蚀性。电化学阻抗谱(EIS)等效电路曲线拟合分析表明,电解质与衬底之间存在两个界面,而SNC632合金的电荷转移电阻(Rct)要比SN63合金的高。浸泡腐蚀试验与电化学腐蚀结果一致,SNC632合金表现出较高的耐腐蚀性。Cu元素的添加导致在SNC632合金并未出现含金属间化合物的次生铜相而出现单相Cu,进而提高其抗腐蚀性。
基金
financially supported by the World Class 300 R&D Program (S2404600)
funded by the Small Business Administration of Korea through the Research Institute of Advanced Materials (041720170037)
Magnesium Technology Innovation Center
