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利用XRD、OM、SEM、EDS、极化曲线测试和浸泡试验分析研究Sr元素添加Mg-6Zn-4Si铸态合金的显微结构和腐蚀行为。Sr元素的添加能够有效地改善Mg-6Zn-4Si合金中初生及共晶Mg2Si相的形貌和尺寸。随着Sr元素添加量的增加,初生Mg2Si相的尺寸先降低后逐渐增加。Sr元素能够有效地改善合金的耐腐蚀性。当Sr添加量为0.5%(质量分数)时,合金具有最优的耐蚀性,此时表现为最高的腐蚀电位,最低的腐蚀电流密度和腐蚀速率。添加Sr元素后,细小且分散均匀的Mg2Si相是耐蚀性提高的主要原因。过量的Sr添加会形成针状Sr Mg Si新相,降低了合金的耐蚀性。
The microstructure and corrosion behavior of Sr-added Mg-6Zn-4Si as-cast alloy were investigated by XRD, OM, SEM, EDS, polarization curves and immersion tests. The addition of Sr can effectively improve the morphology and size of primary and eutectic Mg2Si phase in Mg-6Zn-4Si alloy. With the increase of Sr addition, the size of primary Mg2Si phase first decreases and then increases gradually. Sr element can effectively improve the corrosion resistance of the alloy. When Sr is added in an amount of 0.5% (mass fraction), the alloy has the best corrosion resistance, which shows the highest corrosion potential, the lowest corrosion current density and the corrosion rate. Adding Sr element, the fine and evenly dispersed Mg2Si phase is the main reason for corrosion resistance. Excessive addition of Sr forms a new phase of acicular Sr Mg Si, reducing the corrosion resistance of the alloy.