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为改善AZ91镁合金的耐蚀性能,对其表面进行了固溶时效和氮铝(N+Al)双离子注入复合改性处理。通过X射线衍射(XRD)、俄歇电子能谱(AES)、电化学综合测试系统、显微硬度计分析比较了处理前后试样的表面结构、元素浓度-深度分布、抗腐蚀性能和显微硬度。XRD结果表明,双离子共注后AZ91镁合金表面改性层由Mg、Al12Mg17、MgAl2O4、AlN等物相组成,且Mg和Al12Mg17衍射峰位和强度发生了明显改变。AES分析发现,表面存在约30 nm由Mg、Al、O等元素组成的改性层,注入层深度达到130 nm。双离子共注后试样的显微硬度较基体和固溶时效时分别提高了27.1%和10.4%。在3.5%饱和NaCl溶液中,双离子共注入试样的极化电阻分别为基体和固溶时效试样的21.7倍和9.1倍,腐蚀电流密度降为基体的1/10。相同腐蚀条件下的双离子共注入试样表面只产生了少量腐蚀斑,而基体和固溶时效试样表面却出现了大量的腐蚀坑。
In order to improve the corrosion resistance of AZ91 magnesium alloy, the surface of the AZ91 magnesium alloy was solution-treated with aging treatment and double-ion implantation of aluminum and aluminum (N + Al). The surface structure, elemental concentration - depth distribution, corrosion resistance and microstructure of the samples before and after treatment were compared by XRD, Auger electron spectroscopy (AES), electrochemical comprehensive testing system and microhardness tester hardness. XRD results show that the surface modification layer of AZ91 magnesium alloy after double ion co-injection consists of Mg, Al12Mg17, MgAl2O4, AlN and other phases, and the diffraction peaks and intensities of Mg and Al12Mg17 obviously change. AES analysis shows that there is a modified layer of about 30 nm composed of Mg, Al, O and other elements on the surface, and the depth of the implantation layer reaches 130 nm. The microhardness of the sample after double ion co-injection increased by 27.1% and 10.4% respectively compared with the matrix and solution-aging. In 3.5% saturated NaCl solution, the polarization resistance of the double-ion co-injected sample is 21.7 times and 9.1 times that of the solution-aged sample and the corrosion current density is reduced to 1/10 of the matrix. Under the same etching conditions, only a small amount of corrosion spots were generated on the surface of the double-ion co-injection specimen, but a large number of corrosion pits were observed on the surface of the substrate and the solution-aging specimen.