镁稀土合金Mg-Gd-Y-Zr及Mg-Nd-Zn-Zr的强流脉冲电子束表面改性研究

Research on Surface Modification of Magnesium Rare Earth Alloys Mg-Gd-Y-Zr and Mg-Nd-Zn-Zr by High-current Pulsed Electron Beam Surface Treatment

采用强流脉冲电子束技术对Mg-Gd-Y-Zr和Mg-Nd-Zn-Zr两种镁稀土合金进行表面改性处理,并研究了处理后镁合金表层的相组成、形貌和性能变化。结果表明:Mg-Gd-Y-Zr合金经脉冲电子束处理后表层的Mg5Gd转变为Mg3Gd,而Mg-Nd-Zn-Zr合金表层的Mg12Nd相消失形成过饱和固溶体。两种稀土镁合金经脉冲电子束处理后均发生熔化和部分汽化,在快速凝固后表面形成波状形貌,且表面生成大量孪晶。脉冲电子束处理使得两种镁合金表面硬度显著提高。在模拟体液中的腐蚀测试结果显示,上述合金经强流脉冲电子束表面处理后自腐蚀电位均提高,但腐蚀电流密度有所增加。脉冲电子束处理后镁稀土合金表面组织成分均匀化、晶粒细化,稀土元素在镁中的固溶以及缺陷的生成导致表层硬度的提高和耐腐蚀性的改变。

High current pulsed electron beam （HCPEB） surface treatment was applied on two kinds of magnesium rare earth alloys Mg-Gd-Y-Zr and Mg-Nd-Zn-Zr. The phase component, surface morphology and properties of Mg alloy surface after modification treatment were investigated. The results show that MgsGd transforms into Mg3Gd in Mg-Gd-Y-Zr alloy after HCPEB treatment. Mg12Nd on the surface of Mg-Nd-Zn-Zr alloy surface disappears after HCPEB, then, the supersaturated solid solution appears. The HCPEB treatments induce melting and partial evaporation in the two Mg alloys, and wavy morphologies appear with the formation of many twins in the surface layer. The surface hardness of the two Mg alloys significantly increase after HCPEB treatment. The corrosion measurement in simulated body fluid shows that, the self corrosion potential of the two alloys increases while the corrosion current density increases. The composition of rare earth magnesium alloy surface after HCPEB is uniformn and the grain size is refined. The solid solution of rare earth element in Mg and the formation of defects lead to the increase of surface hardness and the change of corrosion resistance.