Sr添加Mg-6Zn-4Si铸态合金的腐蚀行为研究

Corrosion behavior of as-cast Mg-6Zn-4Si alloy with minor Sr addition

摘要:

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。适量的Sr元素能够有效地改善Mg-6Zn-4Si合金中初生及共晶Mg2Si相的形貌和尺寸。随着Sr元素含量的增加，初生Mg2Si相的尺寸先降低后逐渐增加。腐蚀测试结果表明：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%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SrMgSi新相，降低了合金的耐蚀性。

Abstract:

The microstructure and corrosion resistance of Mg-6Zn-4Si alloy with Sr addition were studied using XRD, OM, SEM, EDS, potentiodynamic polarization and immersion testing. A proper Sr addition observably modifies the morphologies and sizes of primary and eutectic Mg2Si phases in Mg-6Zn-4Si alloy. The grain size of the primary Mg2Si decreased initially and then gradually increased with the increasing of Sr amount. Sr significantly improves the corrosion resistance of Mg-6Zn-4Si alloy. The ternary alloy with 0.5Sr has the optimal corrosion resistance, which exhibits the highest corrosion potential, the lowest corrosion current density and corrosion rate. The homogeneous dispersion of fine Mg2Si particles with Sr element is responsible for the improvement of corrosion resistance. Excessive Sr (≥1.0%) leads to the generation of SrMgSi new phase, which has unfavorable effects on the corrosion resistance of the alloys.