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采用海洋大气环境暴露实验以及XRD,OM和SEM等分析手段,对比研究了5A90铝锂合金和2D12铝合金的显微组织、腐蚀行为和力学性能,探讨了腐蚀机制。结果表明,5A90铝锂合金的主要强化相为δ′(Al3Li)和T(Al2Mg Li),细密析出呈弥散分布,其微观腐蚀形貌与2D12铝合金存在明显区别,即晶界和晶粒内部同时发生腐蚀,晶间腐蚀特征不明显。用腐蚀失重表征铝合金腐蚀损伤程度,5A90合金腐蚀过程不符合幂函数规律,腐蚀造成的力学损伤明显大于2D12合金的。5A90合金的原始断裂方式以撕裂和韧窝为主,环境腐蚀作用促进合金由韧性断裂向沿晶脆性断裂的转变,严重降低材料塑性。
The microstructure, corrosion behavior and mechanical properties of 5A90 Al-Li alloy and 2D12 aluminum alloy were comparatively studied by using marine atmospheric environment exposure experiments and XRD, OM and SEM analysis methods. The corrosion mechanism was also discussed. The results show that the main strengthening phases of 5A90 Al-Li-Al alloy are δ ’(Al3Li) and T (Al2Mg Li), the fine precipitates are diffusely distributed, and the micro-corrosion morphology is obviously different from that of 2D12 aluminum alloy, At the same time corrosion, intergranular corrosion characteristics are not obvious. Corrosion loss is used to characterize the corrosion damage of aluminum alloy. The corrosion process of 5A90 alloy does not accord with the law of power function, and the mechanical damage caused by corrosion is obviously larger than that of 2D12 alloy. The primary fracture mode of 5A90 alloy is mainly tearing and dimple, and the environmental corrosion promotes the transition from ductile fracture to intergranular brittle fracture, which seriously reduces the plasticity of the material.