冷却方式对Zn-11Al-3Mg-0.2Si-xTi合金组织及耐蚀性的影响

    Effect of Cooling Methods on Microstructure and Corrosion Resistance of Zn-11Al-3Mg-0.2Si-xTi Alloy

    • 摘要: 采用钢模冷却、铜模冷却和铜模+水冷3种冷却方式制备Zn-11Al-3Mg-0.2Si-xTi(x=0wt%、0.09wt%)合金,采用扫描电镜(SEM)、能谱仪(EDS)、中性盐雾实验、电化学试验,研究了冷却方式对Zn-11Al-3Mg-0.2Si-xTi合金组织及耐蚀性的影响。结果表明:合金化和冷却速度对Zn-11Al-3Mg-0.2Si合金组织和性能具有重要影响。Zn-11Al-3Mg-0.2Si合金由α-Al、η-Zn、共晶MgZn2、Zn/Al/MgZn2(Mg2c)三元共晶组成。Ti的加入及冷却速度的提高均可有效抑制Mg2Zn11的生长。铜模+水冷条件下获得的Zn-11Al-3Mg-0.2Si-0.09Ti合金中α-Al枝晶细化,形核量增多,共晶MgZn2相尺寸减小,改善了合金中的离异共晶组织,Zn/Al/MgZn2三元共晶含量增加,Mg2Zn11相消失,此时合金的耐蚀性能最好。

       

      Abstract: Zn-11Al-3Mg-0.2Si-xTi (x=0wt%, 0.09wt%) alloys were prepared by steel die cooling, copper die cooling and copper die+water cooling, and the effects of cooling method on the microstructure and corrosion resistance of Zn-11Al-3Mg- 0.2Si-xTi alloys were studied by means of scanning electron microscope (SEM), energy dispersive spectrometer (EDS), neutral salt spray test and electrochemical test. The results show that alloying method and controlled cooling rate have important influence on the microstructure and properties of Zn-11Al-3Mg-0.2Si alloy. The Zn-11Al-3Mg-0.2Si alloy is composed of α-Al, η-Zn, eutectic MgZn2, Zn/Al/MgZn2(Mg2Zn11) ternary eutectic. The addition of Ti and the increase of cooling rate can effectively inhibit the growth of Mg2Zn11 phase. Under the copper die+water cooling condition, the α-Al dendrites in Zn-11Al-3Mg-0.2Si-0.09Ti alloy are refined, the nucleation amount increases, the eutectic MgZn2 phase size decreases, the divorced eutectic structure in the alloy is improved, the content of Zn/Al/MgZn2 ternary eutectic increases, and the Mg2Zn11 phase disappears, and the alloy shows the best corrosion resistance properties.

       

    /

    返回文章
    返回