AZ31镁合金盐浴渗铝改善耐蚀性机制分析

采用真空热扩散渗铝的方法对AZ31镁合金进行表面合金化处理，在不同参数下得到厚度不一的渗铝层，对渗层的显微组织、物相组成进行了分析，并分析了渗铝试样的耐腐蚀性能和显微硬度.绘制了AZ31镁合金基体以及经过400℃扩散渗铝4 h后的试样的极化曲线.结果表明，渗层主要由Mg₁₇Al₁₂，Mg₃Al₂和α-Mg等组成，渗层厚度随扩散温度提高而增加，400℃恒温热扩散4 h时，在基体表面获得了连续且均匀细密的渗铝层，显微硬度值从基体的53 HV提高到80~85 HV，同时，该方法使得镁合金的自腐蚀电位提高了约105 mV，而镁合金的自腐蚀电流密度降低了一个数量级，这表征着镁合金的耐蚀性能得到提高.

Research on properties of diffusion aluminizing layer on AZ31B magnesium alloy

Surface alloying treatment was conducted by vacuum thermal diffusion aluminized on AZ31 magnesium alloy.The microstructure,phase structure, corrosion resistance and micro-hardness of the aluminized layer by different parameters were analyzed and studied.The electrochemical corrosion polarization curves of the alloy were measured before and after being aluminized for 4 h at 400℃.Test results show that aluminized layer is mainly composed of Mg₁₇Al₁₂, Mg₃Al₂ and α-Mg. The thickness of diffusion layer increases with the diffusion temperature. After diffusion aluminizing treatment at 400℃ for 4 h, a continuous and fine aluminized layer, on the surface of the matrix was obtasneel obtained the micro-hardness value increased from HV 53 to HV 80-85 of the base metal. At the same time, the method enables the corrosion potential of magnesium alloys to increase about 105mV, and the corrosion current density to reduce one order of magnitude, which characterized of the magnesium alloy corrosion resistance is improved.