New insights into intergranular corrosion mechanism of high-strength Al-Zn-Mg-Cu alloys

IF 7.4 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Corrosion Science Pub Date : 2025-09-26 DOI:10.1016/j.corsci.2025.113364

Hao Liu , Liankui Wu , Fahe Cao , Qingqing Sun

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引用次数: 0

Abstract

This study provides new insights into the intergranular corrosion (IGC) mechanism of high-strength Al-Zn-Mg-Cu alloys (i.e., 7000 series Al alloys). Utilizing FIB, SEM, and TEM techniques, the microstructural evolution of 7055, 7150, and 7085 Al alloys during IGC in 3.5 wt% NaCl solution was characterized. Results confirm that IGC preferentially initiates at anodic grain boundary precipitates (GBPs, MgZn₂) and propagates along precipitation-free zones (PFZs) and the adjacent aluminum matrix. Furthermore, nano/submicro-scale Al₂Cu precipitates (50 ∼ 300 nm) and Cu clusters (∼50 nm) distributed along the corroded grain boundaries serve as active cathodic phases, promoting IGC propagation through PFZs while simultaneously accelerating localized dissolution of the adjacent aluminum matrix. This cathodic acceleration contributes to a characteristic corrosion width of 100 ∼ 300 nm within the aluminum matrix. ‌The discovery of Al₂Cu precipitates/Cu clusters and their roles in intergranular corrosion has significantly enhanced the understanding of IGC mechanism in 7000 series Al alloys.

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高强度Al-Zn-Mg-Cu合金晶间腐蚀机理的新认识

本研究为高强度Al- zn - mg - cu合金（即7000系铝合金）的晶间腐蚀（IGC）机理提供了新的认识。利用FIB、SEM和TEM技术，对7055、7150和7085铝合金在3.5 wt% NaCl溶液中IGC过程中的组织演变进行了表征。结果证实，IGC优先从阳极晶界析出（GBPs、MgZn2）开始，并沿无析出区（PFZs）和邻近的铝基体扩散。此外，沿腐蚀晶界分布的纳米/亚微米级Al2Cu析出相（50 ~ 300 nm）和Cu团簇（~ 50 nm）作为活跃的阴极相，促进了IGC在pfz中的传播，同时加速了邻近铝基体的局部溶解。这种阴极加速导致铝基体内的特征腐蚀宽度为100 ~ 300 nm。Al2Cu析出物/Cu团簇及其在晶间腐蚀中的作用的发现，极大地提高了对7000系铝合金IGC机制的认识。

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来源期刊

Corrosion Science 工程技术-材料科学：综合

CiteScore

13.60

自引率

18.10%

发文量

763

审稿时长

46 days

期刊介绍： Corrosion occurrence and its practical control encompass a vast array of scientific knowledge. Corrosion Science endeavors to serve as the conduit for the exchange of ideas, developments, and research across all facets of this field, encompassing both metallic and non-metallic corrosion. The scope of this international journal is broad and inclusive. Published papers span from highly theoretical inquiries to essentially practical applications, covering diverse areas such as high-temperature oxidation, passivity, anodic oxidation, biochemical corrosion, stress corrosion cracking, and corrosion control mechanisms and methodologies. This journal publishes original papers and critical reviews across the spectrum of pure and applied corrosion, material degradation, and surface science and engineering. It serves as a crucial link connecting metallurgists, materials scientists, and researchers investigating corrosion and degradation phenomena. Join us in advancing knowledge and understanding in the vital field of corrosion science.