微量钪添加对Al-Cu合金时效析出及电化学腐蚀行为的影响

Effect of Minor Scandium Addition on Precipitation and Electrochemical Corrosion of Al-Cu Alloy

采用透射电子显微镜及三维原子探针观察及统计分析研究了0.3%(质量分数)Sc添加对Al-2.5%Cu合金时效析出行为的影响,采用电化学分析方法对比了Sc添加前后合金的电化学腐蚀行为,藉此建立了时效析出第二相与电化学腐蚀性能之间的关联并阐明了Sc的微合金化作用。研究结果表明:Sc的加入显著影响了Al-Cu合金中θ'-Al2Cu的析出,使得析出相密度增加尺寸减小,同时由于Sc原子在析出相/基体界面的偏聚降低了界面能,从而影响了合金的电化学腐蚀行为,使得含Sc合金的耐蚀性明显优于纯Al-Cu合金。结果可以为耐腐蚀、高性能Al-Cu合金的微合金化材料设计提供参考。

The effect of 0.3% Sc addition on precipitation of Al-2.5% Cu alloy was studied and statistically analyzed by using transmission electron microscope and three-dimentional atom probe, respectively. The electrochemieal corrosions of the alloy with and without Sc addition were compared by electrochemical analysis, with which we expect to develop the relationship between electrochemical corrosion and precipitates and reveal its dependence on the Sc microaUoying effect. The experimental results showed that the Sc addition remarkably affected the θ＇-Al2Cu precipitation, increasing the number density and reducing the sizes of precipitates, and also promoted the anti-cotrosion capability. The significant microalloying effect on precipitation was ascribed to the Sc atoms segregation at the precipitate/matrix interface that decreased the interface energy. The improvement in electrochemical corrosion was related to the more homogenous precipitate distribution as well as to the decrease in precipitate/matrix interface energy. The experimental results presented in this paper could be used to artificially control the precipitation and hence improve the corrosion behavior of heat-treatable Al alloys by microalloying