重稀土(Ho,Y)变质对工业纯铝显微组织和电化学腐蚀行为的影响

Effect of heavy rare earth(Ho,Y) modification on microstructure and electrochemical corrosion behaviors of commercial pure aluminum

采用金相显微镜、扫描电子显微镜/能谱仪和电化学工作站对重稀土Ho、Y变质的1035工业纯铝的显微组织和电化学腐蚀行为进行了研究。研究结果发现,Ho、Y变质具有细化铝晶粒的作用,添加w(Ho)=0.2%和w(Y)=0.2%～0.3%时对铝晶粒细化效果最明显。Ho、Y主要富集于α-Al的晶界处,退火可降低Ho的富集程度,增加Y的富集程度。Ho、Y变质的工业纯铝在NaCl介质中的耐电化学腐蚀性能远高于在NaOH介质中的耐腐蚀性能,添加w(Ho)=0.2%的工业纯铝在NaCl介质中具有最高的腐蚀电位和表面钝化能力;工业纯铝中的Fe对耐电化学腐蚀性能有明显的负面作用。

The microstructure and electrochemical corrosion behaviors have been studied using metallurgical microscope, scanning electronic microscope/energy dispersive spectro- scope（SEM/EDS） and electrochemical workstation. Experimental results show that, the Ho and Y modification can refine the primary a-A1 grains obviously,while add w（Ho） = 0.2% or w（Y） =0.2% -0.3% separately. Ho and Y mainly enrich at the boundary of a-A1 grains and the annealing treatment can decrease the enrichment of Ho, but increase the enrichment of Y. The electrochemical corrosion-resistance ability of commercial pure aluminum being modified with Ho and Y is much higher in NaC1 solution than in NaOH. The commercial alu- minum being modified with w（Ho） =0.2% possesses the highest electric potential corrosion and surface passivation ability in NaCl solution. Moreover, the Fe content in pure aluminum possesses negative effect on the corrosion-resistance ability.