氢在不同成分和显微组织的Mg-Ni合金电极中的扩散能力研究

Diffusion ability of hydrogen in Mg-Ni alloy electrode with different compositions and microstructures

采用机械球磨的方法,制备了不同成分和显微组织的MgxNi(x=1%、1.5%、2%(原子分数))合金粉,并采用X射线衍射(XRD)和扫描电子显微镜的方法研究了Mg/Ni比对机械球磨过程中Mg-Ni合金粉末组织结构演变的影响。在不同的电位扫描速度下,对具有不同Mg/Ni比和显微组织结构的Mg-Ni合金电极循环伏安曲线进行了测量,并由此计算出了氢在这些电极中的扩散系数,分析了合金成分和显微组织对Mg-Ni合金电极中氢扩散能力的影响。其结果表明,降低Mg/Ni比,能提高Mg-Ni合金在球磨过程中非晶相的形成能力,Mg-Ni和Mg1.5Ni合金获得完全非晶相的球磨时间分别是120和160h。在由细小、分散并且完全非晶态的Mg-Ni合金颗粒制备的电极中,氢表现出较强的扩散能力,其扩散系数为1.98×10-8cm2/s。

In this study,MgxNi（x=1,1.5,2,in atom percent） alloy powders with different microstructures were prepared by using mechanical ball milling method.The effect of Mg/Ni ratio on the microstructure evolution of the alloys during ball milling was investigated by X-ray diffraction（XRD） and scanning electronic microscope（SEM） observation.The cyclic voltammetry curves of the Mg-Ni alloy electrodes with the different compositions and microstructure were measured under the different potential scan rates,and the hydrogen diffusion coefficients in these electrodes were calculated.The results show that lowering Mg/Ni ratio can promote the glass forming ability of Mg-Ni alloys during ball milling,and the complete amorphous structure can be obtained after ball-milled for 120 and 160h for MgNi and Mg1.5Ni alloys,respectively.Hydrogen exhibits high diffusion ability in the electrode made by the fine and disperse MgNi alloy powders in the complete amorphous strcuture.The hydrogen diffusion coefficient was 1.98×10-8 cm2/s in it.