Abstract

The cyclic deep cryogenic treatment was proposed to improve both the hardness and corrosion resistance of the high strength 7075 aluminum alloy. The effect of different CDCT times on the exfoliation corrosion and intergranular corrosion of the alloys were observed by scanning electron microscope. The corrosion behaviors of the alloys were monitored by electrochemical techniques. The hardness of the alloy was measured by Vickers hardness tester. Furthermore, the microstructures of the alloys were examined by transmission electron microscope. The results show that the corrosion resistance and hardness are strongly affected by the precipitate state. The discontinuous grain boundary precipitates and the wide precipitate free zones will enhance the corrosion resistance. The fine precipitates distributed evenly in the matrix can increase the hardness. After the CDCT, the corrosion resistance is remarkably improved without sacrificing the hardness. The best combination of the hardness and corrosion resistance is exhibited for the alloy treated with the CDCT twice.

Graphic Abstract

中文翻译：

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循环深冷处理对7075合金耐腐蚀性能的影响

摘要

提出循环深冷处理以提高高强度7075铝合金的硬度和耐腐蚀性。通过扫描电镜观察不同CDCT时间对合金剥落腐蚀和晶间腐蚀的影响。通过电化学技术监测合金的腐蚀行为。合金的硬度采用维氏硬度计测定。此外，通过透射电子显微镜检查合金的微观结构。结果表明，耐蚀性和硬度受析出状态的影响很大。不连续的晶界析出物和宽的无析出物区将增强耐腐蚀性。均匀分布在基体中的细小析出物可以提高硬度。在CDCT之后，在不牺牲硬度的情况下显着提高了耐腐蚀性。经 CDCT 两次处理的合金表现出硬度和耐腐蚀性的最佳组合。

图形摘要