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通过浸泡腐蚀质量损失试验,研究了不同凝固冷却速度(空冷、水冷和盐水冷)对AZ31和AZ81镁合金在3.5%Na Cl溶液中耐腐蚀性能的影响。研究结果表明,镁合金中Mg17Al12相的尺寸、形貌、分布、析出量及合金凝固组织的均匀性对抗Na Cl溶液腐蚀产生重要影响;Mg17Al12相对镁合金耐蚀性能具有双重作用(起阻障及电偶阴极的作用);同时凝固组织均匀化程度的改善能提高耐蚀性能。在3种因素的叠加作用下,AZ31合金的耐蚀性能随着冷却速度的提高而得以改善,而AZ81合金的耐蚀性能则表现为:空冷>盐水淬>水冷。
The effect of different solidification cooling rates (air cooling, water cooling and brine cooling) on the corrosion resistance of AZ31 and AZ81 magnesium alloys in 3.5% NaCl solution was studied by immersion corrosion mass loss test. The results show that the size, morphology, distribution, amount of precipitated Mg17Al12 phase and the homogeneity of alloy solidification microstructure have an important effect on the corrosion resistance of NaCl solution. The corrosion resistance of Mg17Al12 alloy has a dual effect Galvanic cathode role); the same time, improve the degree of homogenization of the solidified structure can improve the corrosion resistance. The corrosion resistance of AZ31 alloy improved with the increase of cooling rate under the superposition of three factors, while the corrosion resistance of AZ81 alloy showed as follows: air cooling> brine quenching> water cooling.