大气下纯镁表面扩散锌钇渗层组织和性能

Study of Microstructure and Property of Zinc-Yttrium Coating on Pure Magnesium by Atmosphere Solid Diffusion

摘要:

大气下采用固态扩散锌钇共渗的方法，在390 ℃对纯镁进行表面合金化改性处理。采用OM、SEM、EDS、XRD和显微硬度、电化学腐蚀极化曲线测试等方法分析渗层的组织结构、显微硬度和耐蚀性能。结果表明，经表面合金化处理，在纯镁表面获得了致密的渗层，厚约900 μm。渗层由过渡层和合金反应层两部分组成，过渡层是α-Mg固溶体，合金反应层由大量的Mg7Zn3和α-Mg固溶体及α-Mg和MgZn片层状共晶组织组成，材料表层的显微硬度有很大提高，平均硬度约为纯镁的4倍，自腐蚀电位比纯镁正移87 mV，自腐蚀电流密度降低了约1个数量级，耐腐蚀性能明显改善

Abstract:

The surface modification treatment on pure magnesium was conducted at 390 ℃ by atmosphere solid zinc-yttrium co-diffusing. The microstructure, the microhardness and the corrosion resistance of the diffusing layer were investigated with optical microscope, SEM, EDS, XRD, microhardness test and the electrochemical corrosion polarization curves test. The results show that the dense diffusing layer with an thickness of 900 μm has formed on the surface of pure magnesium after surface modification treatment. The diffusion layer contains a transition layer and an alloy reaction layer. The transition layer is α-Mg solid solution. The alloy reaction layer contains a plenty of Mg7Zn3, α-Mg solid solution and α-Mg+MgZn lamellar eutectic structure. The microhardness of the surface diffusion alloying layer increases significantly. The average microhardness is about 4 times higher than that of magnesium matrix. The open circuit potential of the alloyed specimen increases by 87 mV. The corrosion current density of alloyed specimen decreases by one order of magnitude. Its corrosion resistance is improved obviously