铝和镁对锌铝镁合金凝固组织与力学性能的影响

Solidification Microstructure and Mechanical Properties of Zn-Al-Mg Alloy with Different Aluminum and Magnesium Contents

采用扫描电镜（SEM）和万能电子试验机分析和测试了不同镁含量（1%-5%,质量分数）和铝含量（4%-8%,质量分数）锌铝镁合金的凝固组织与力学性能。研究表明：当铝含量为6%时,随着镁含量的增加,Zn-6%Al-Mg合金中的MgZn2相、二元Zn/Al和三元Zn/Al/MgZn2共晶体数量明显增加,当镁含量为3%时达到最大值。当镁含量超过3%时,出现较多粗大的Al/MgZn2二元共晶体。铝含量小于6%时,在Zn-Al-3%Mg合金中形成粗大的Mg2Zn11相和大量的Zn/Al/Mg2Zn11三元共晶体;当铝含量超过6%时,在Zn-Al-3%Mg合金中形成粗大的MgZn2相和大量的Al/MgZn2二元共晶体。当铝含量为6%时,Zn-6%Al-Mg合金的抗拉强度和硬度随着镁含量的增加呈现先增加后降低的趋势,但合金的延伸率一直下降,Zn-6%Al-3%Mg合金的抗拉强度和硬度最高。当镁含量为3%时,Zn-Al-3%Mg合金的抗拉强度、延伸率和硬度随着铝含量的增加都呈现先增加后降低的趋势,Zn-6%Al-3%Mg合金的综合力学性能最好。

The solidification microstructures of Zn-Al-Mg alloy containing 1% - 5% Mg and 4%- 8% Al were observed using scanning electron microscopy （SEM） and its mechanical properties were measured by electron universal testing machine. The results showed that the amount of MgZn2 phase, Zn/Al binary and Zn/Al/MgZn2 ternary eutectic phases in Zn-6% Al-Mg alloy increased significantly with the increase of Mg content. When Mg content was 3%, the amounts reached the maximum. When Mg content exceeded 3%, a lot of Al/MgZn2 binary eutectic phases occurred. When Al content was less than 6% , coarse Mg2Zn11 phase and a large amount of Zn/Al/ Mg2Zn11 ternary eutectic phases occurred in Zn-Al-3% Mg alloy. When Al content exceeded 6%, coarse MgZn2 phase and a large amount of AI/MgZn2 binary eutectic phases formed in the alloy. When Al content was 6% , the tensile strength and hardness of Zn-6% Al-Mg alloy increased at first and then decreased with the increase of Mg content while its elongation decreased continuously. Zn-6% Al-3% Mg alloy possessed the highest tensile strength and hardness. When Mg content was 3%, the tensile strength, elongation and hardness of Zn-Al-3% Mg alloy increased first and then decreased with the increase of Al content. Zn-6% Al-3% Mg alloy possessed the best comprehensive mechanical properties.