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为了提高镁合金的耐蚀性能,首先采用表面机械研磨的方法实现了AZ91D镁合金表面纳米化,然后研究了Ce、Nd、Y熔盐扩渗对AZ91D镁合金表层组织及耐蚀性能的影响。采用扫描电镜(SEM)、透射电镜(TEM)以及X射线衍射(XRD)对扩渗层形貌及物相进行了表征,并利用电化学工作站测试了稀土扩渗后合金在3.5%NaCl水溶液中的极化曲线。研究结果表明,经过表面纳米化及熔盐扩渗稀土后,AZ91D镁合金表面形成一层均匀、致密的稀土扩渗层,合金耐蚀能力明显提高,腐蚀电流密度降低一个数量级,渗层厚度随着扩渗时间的延长而增加,扩渗层变得更连续、致密,XRD及TEM结果表明,扩渗层主要由α-Mg,Mg_(17)Al_(12)和富稀土相Al2RE(Ce/Nd/Y)组成。
In order to improve the corrosion resistance of AZ91D magnesium alloy, the surface of the AZ91D magnesium alloy was first nanostructured by surface mechanical polishing. Then the effects of Ce, Nd and Y molten salt infiltration on the surface microstructure and corrosion resistance of AZ91D magnesium alloy were studied. The morphology and phase of the propagation layer were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical workstation was used to test the properties of the alloy after 3.5% NaCl solution The polarization curve. The results show that after surface nanocrystallization and molten salt diffusion rare earth, AZ91D magnesium alloy surface formed a uniform, dense rare earth infiltration layer, the corrosion resistance of the alloy increased significantly, the corrosion current density decreased by one order of magnitude, with the thickness of the layer The results of XRD and TEM show that the infiltration layer is mainly composed of α-Mg, Mg_ (17) Al_ (12) and Al_2O RE (Ce / Nd / Y).