均匀化对Mg-6Zn-0.25Ca镁合金耐蚀性能的影响

Effect of Homogenization on the Corrosion Resistance of Mg-6Zn-0.25Ca Magnesium Alloy

本文研究了均匀化对Mg-6Zn-0.25Ca合金耐腐蚀性能的影响。通过XRD、OM、SEM、失重、析氢实验研究了均匀化对Mg-6Zn-0.25Ca合金的显微组织及耐腐蚀性能。实验研究表明铸态Mg-6Zn-0.25Ca合金由α-Mg相以及第二相Ca2Mg6Zn3、Mg2Ca组成,均匀化处理后Mg-6Zn-0.25Ca合金晶粒尺寸稍有变大但是晶粒更加均匀,合金是由α-Mg相以及第二相Mg2Ca组成,由于Ca2Mg6Zn3相的熔点小于均匀化的温度,所以Ca2Mg6Zn3相溶于基体中,Ca2Mg6Zn3相溶于基体导致了合金第二相体积分数减少,第二相体积分数减少有效的降低了电偶腐蚀的发生。析氢失重实验表明进行均匀化处理有效地降低了Mg-6Zn-0.25Ca合金在3.5%NaCl水溶液24小时氢气的产生量,降低了析氢失重速率,即增强了Mg-6Zn-0.25Ca合金的耐腐蚀性能。对腐蚀产物膜进行分析,结果发现经过均匀化处理的合金生成的腐蚀产物膜更加致密,可以有效的增强合金的耐腐蚀性能。

In this paper,the effect of homogenization on the corrosion resistance of Mg-6Zn-0.25Ca alloy was studied.The microstructure and corrosion resistance of Mg-6Zn-0.25Ca alloy by homogenization were studied by XRD,OM,SEM,weight loss and hydrogen evolution experiments.Experimental results show that the as-cast Mg-6Zn-0.25Ca alloy is composed ofα-Mg phase and the second phases Ca2Mg6Zn3 and Mg2Ca.After homogenization,the grain size of Mg-6Zn-0.25Ca alloy is slightly larger but the grain is more uniform,the alloy is composed ofα-Mg phase and the second phase Mg2Ca,because the melting point of Ca2Mg6Zn3 phase is less than the homogenization temperature,so Ca2Mg6Zn3 phase is dissolved in the matrix,and Ca2Mg6Zn3 phase is dissolved in the matrix,which leads to the reduction of the second phase volume fraction of the alloy,and the decrease of the volume fraction of the second phase effectively reduces the occurrence of galvanic corrosion.The results of hydrogen evolution weight loss experiments show that the homogenization treatment can effectively reduce the hydrogen production of Mg-6Zn-0.25Ca alloy in 3.5%NaCl aqueous solution for 24 hours,reduce the hydrogen evolution weight loss rate,and enhance the corrosion resistance of Mg-6Zn-0.25Ca alloy.The corrosion product film was analyzed,and it was found that the corrosion product film generated by the homogenized alloy was denser,which could effectively enhance the corrosion resistance of the alloy.