Microstructure, MAO performance, interfacial characteristics and corrosion behavior of FSW joint of Al–Mg-Sc alloy

IF 4.3 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Chemistry and Physics Pub Date : 2024-10-15 DOI:10.1016/j.matchemphys.2024.130046

Mingjin Wu , Bingqian Li

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引用次数: 0

Abstract

The microstructure evolution, micro-arc oxidation (MAO) performance, and corrosion behavior of Al–Mg-Sc alloy friction stir welded (FSW) joint were investigated. The microstructure observations indicated that compared with the base metal (BM), the stirring zone (SZ) and thermo-mechanical affected zone (TMAZ) showed notable grain defects and an enormous number of high angle grain boundaries (HAGBs). Additionally, a more conspicuous presence of non-uniform recrystallized grains and HAGBs was noticed in the thickness direction within the SZ. FSW process induced the precipitation of Al₃Mg₂ (β phase) at grain boundaries in the heat-affected zone (HAZ) of joint. The microstructural changes and precipitation induced by the FSW process influenced the electrical conductivity, resulting in the differences in micro-arc discharge in various zones of the FSW joint in MAO process, which in turn affected the thickness, porosity, and corrosion resistance of MAO ceramic film. HRTEM observation suggested that a transition layer composed of nanocrystalline and amorphous Al₂O₃ with average thickness of 2–4 nm was found at the film/substrate interface. Electrochemical tests suggested that a heterogeneous structure in various regions of FSW joint resulted in varying susceptibility to localized corrosion. HAZ/TMAZ had the worst anti-corrosion performance. After MAO treatment, the anti-corrosion performance of SZ and HAZ/TMAZ in FSW joint was significantly improved, especially SZ.

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Al-Mg-Sc 合金 FSW 接头的微观结构、MAO 性能、界面特性和腐蚀行为

研究了铝镁钪合金搅拌摩擦焊（FSW）接头的微观组织演变、微弧氧化（MAO）性能和腐蚀行为。显微组织观察结果表明，与母材（BM）相比，搅拌区（SZ）和热机械影响区（TMAZ）出现了明显的晶粒缺陷和大量高角度晶界（HAGB）。此外，在 SZ 内的厚度方向上，非均匀再结晶晶粒和 HAGB 的存在更为明显。在接头热影响区（HAZ）的晶界处，FSW 过程诱发了 Al3Mg2（β 相）的析出。FSW 过程引起的微观结构变化和析出影响了导电性，导致 MAO 过程中 FSW 接头不同区域的微弧放电存在差异，进而影响了 MAO 陶瓷膜的厚度、孔隙率和耐腐蚀性。HRTEM 观察表明，在薄膜/基底界面上发现了由纳米晶和无定形 Al2O3 组成的过渡层，平均厚度为 2-4 nm。电化学测试表明，FSW 接头不同区域的异质结构导致对局部腐蚀的敏感性不同。HAZ/TMAZ 的抗腐蚀性能最差。经过 MAO 处理后，SZ 和 HAZ/TMAZ 在 FSW 接头中的抗腐蚀性能明显改善，尤其是 SZ。

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来源期刊

Materials Chemistry and Physics 工程技术-材料科学：综合

CiteScore

8.70

自引率

4.30%

发文量

1515

审稿时长

69 days

期刊介绍： Materials Chemistry and Physics is devoted to short communications, full-length research papers and feature articles on interrelationships among structure, properties, processing and performance of materials. The Editors welcome manuscripts on thin films, surface and interface science, materials degradation and reliability, metallurgy, semiconductors and optoelectronic materials, fine ceramics, magnetics, superconductors, specialty polymers, nano-materials and composite materials.