Nd对Mg-11Li-3Al- -2Zn-0.2Zr合金组织、力学性能及腐蚀行为的影响

Effect of Nd on the microstructure, mechanical properties, and corrosion of Mg-11 Li-3Al-2Zn-0.2Zr alloy

  • 摘要: 研究稀土Nd对均匀化态Mg-11Li-3Al-2Zn-0.2Zr合金组织、力学性能及腐蚀行为的影响.通过真空感应熔炼制备镁锂合金铸锭, 经均匀化处理(280 ℃, 24 h)得到均匀化态Mg-11Li-3Al-2Zn-xNd-0.2Zr(x=0, 0.5, 1.0, 1.5)合金.采用XRD和SEM分析合金的显微组织, 并对合金进行拉伸试验和断口分析.采用电化学法和析氢失重法研究合金在3.5 %NaCl溶液中的腐蚀行为.结果表明:Mg-11Li-3Al-2Zn-0.2Zr合金主要含有β-Li、AlLi、MgLi2Al相, Nd的加入使合金中形成NdAl3相.随着Nd含量的增加, 合金的强度和塑性呈先增大后降低的趋势. Mg-11Li-3Al-2Zn-1Nd-0.2Zr合金表现出较优的力学性能, 其抗拉强度和延伸率相对于Mg-11Li-3Al-2Zn-0.2Zr合金分别提高了28.8 %和51.3 %.稀土Nd的添加使合金的耐蚀性能提高.

     

    Abstract: The effect of Nd on the microstructure, mechanical properties and corrosion of homogenized Mg-11Li-3Al-2Zn-0.2Zr alloy was studied. The cast ingots were fabricated in a vacuum induction furnace. The as-cast Mg-11Li-3Al-2Zn-xNd-0.2Zr (x=0, 0.5, 1.0, 1.5) alloy was homogenized at 280 ℃ for 24 h. XRD and SEM were used to analyze the microstructure of the alloy, and the tensile test and fracture analysis were carried out. The corrosion of alloy in 3.5% NaCl solution was studied by electrochemical method and hydrogen evolution test. The results show that Mg-11Li-3Al-2Zn-0.2Zr alloy mainly consists of β-Li, AlLi, and MgLi2Al phases. The addition of Nd results in the formation of NdAl3 phase. With the increase of Nd content, the strength and plasticity of the alloy increase first and then decrease. Mg-11Li-3Al-2Zn-1Nd-0.2Zr alloy shows the best mechanical properties, whose tensile strength and elongation increase by 28.8 % and 51.3 % respectively compared with Mg-11Li-3Al-2Zn-0.2Zr alloy. The addition of Nd improves the corrosion resistance of the alloy. Mg-11Li-3Al-2Zn-0.5Nd-0.2Zr alloy, with a more positive corrosion potential and a lower hydrogen evolution rate, shows the best corrosion resistance.

     

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