高腐蚀条件下用铝合金材料腐蚀机理

铝合金具有低密度、低熔点、高比强度及优良的耐腐蚀性能等特点，被广泛用于航空航天、建筑、船舶等领域。在服役过程中，铝合金的表层氧化膜易受到环境中活性阴离子的破坏而发生腐蚀，对其性能造成严重的损害，故研究铝合金在高腐蚀性环境的腐蚀行为对工程选材具有非常重要的指导意义。选择6061铝合金、2195铝锂合金和7075铝合金为研究对象，对其在特定腐蚀介质中的腐蚀过程和力学性能进行分析，研究了铝合金在特定腐蚀介质中腐蚀形貌与力学性能的变化规律。结果表明：腐蚀初期，在高Cl^-、NO₂^3-、SO₂^4-离子浓度的腐蚀环境中，3种铝合金的氧化膜受到阴离子破坏后发生点腐蚀，使基体暴露在腐蚀环境中，进而发生电化学腐蚀，6061铝合金和2195铝锂合金腐蚀方式是由点腐蚀向面腐蚀转变，7075铝合金腐蚀方式为晶间腐蚀；经过腐蚀后6061铝合金能保持稳定的强度和塑性，7075铝合金和2195铝锂合金的强度和塑性都明显降低。

Corrosion mechanism of aluminum alloy materials under high corrosion conditions

With the advantages of low density, low melting point, high specific strength and excellent corrosion resistance, aluminum alloys are widely used in aerospace, construction, shipbuilding and other industries. During service, the surface oxide film of aluminum alloys is susceptible to corrosion by active anions in the environment, causing serious damage to its performance. Therefore, studying the corrosion behavior of aluminum alloys in a highly corrosive environment is very important for engineering material selection. In this work, 6061 aluminum alloy, 2195 aluminum-lithium alloy and 7075 aluminum alloy were taken as the research objects, their corrosion process and mechanical properties in specific corrosive media were analyzed, and their corrosion morphology and mechanical properties in specific corrosive media were investigated. The results show that in the early stage of corrosion, in a corrosive environment with high Cl^-, , and ^- concentrations, the oxide films of the three aluminum alloys undergo pitting corrosion after being damaged by anions, which exposes the matrix of the alloys to the corrosive environment, resulting in electrochemical corrosion. The corrosion of both 6061 aluminum alloy and 2195 aluminum-lithium alloy progresses from pitting corrosion to surface corrosion, while the 7075 aluminum alloy corrosion mode is intergranular corrosion. After corrosion, 6061 aluminum alloy maintains stable strength and plasticity, but the strength and plasticity of 7075 aluminum alloy and 2195 aluminum-lithium alloy are significantly reduced.