添加Nd、Zn、Ti的Mg2Ni基合金微观组织及氢化动力学

为了提高Mg2Ni基合金的储氢动力学性能，通过熔炼方法分别添加金属元素Nd，Zn和Ti来防止镁的氧化和蒸发，将Mg2Ni基合金在有覆盖剂保护的电阻炉中进行熔炼。借助XRD 和 SEM/EDS研究了铸态合金的相组成和微观组织。采用定容法在Sievert’s型PCT测试仪上测试了合金的氢化动力学性能。Nd、Zn和Ti的添加导致了微量相Mg6Ni和Ni3Ti的生成。Nd和Zn溶解在Mg2Ni基合金的α-Mg、Mg2Ni和MgNi2相中。添加Nd元素后，合金的首次吸氢量高于Mg2Ni的，达到2.86%（质量分数）。Mg2Ni基合金的吸氢动力学性能和活化性能均有所提高。在前3次吸放氢循环过程中，添加Zn和Ti的合金吸氢量和吸氢动力学性能均得到提高。采用Hirooka动力学模型分析了合金的氢化动力学性能及反应机制。

Microstructure and hydrogenation kinetics of Mg2Ni-based alloys with addition of Nd,Zn and Ti

In order to enhance the hydrogen absorption kinetics of the Mg2Ni-based alloys, metal elements （Nd, Zn, and Ti） were added during melting process, respectively. The Mg2Ni-based alloys were melted using an electric resistance furnace under the protection of the covering reagent to prevent the oxidation and the evaporation of magnesium. Phase compositions and microstructures of as-cast alloys were characterized by XRD and SEM equipped with EDS. Hydrogenation kinetics of experimental alloys were investigated by the constant volume method using a Sievert-type apparatus. The addition of Nd, Zn or Ti elements to Mg2Ni results in the formation of minor phases Mg6Ni and Ni3Ti. Nd and Zn are dissolved inα-Mg, Mg2Ni and MgNi2 phases in Mg2Ni-based alloys. With the addition of Nd, the hydrogen content of the first absorption is 2.86%in mass fraction, which is higher than that of the Mg2Ni. Hydrogen absorption kinetics and activation properties of Mg2Ni-based alloys are improved evidently. During the initial three hydrogenation/dehydrogenation cycles, the hydrogen absorption capacity and kinetics properties have been improved for alloys with the addition of transition element Zn or Ti. The kinetics properties of the experimental alloys and absorbing reaction mechanism were also analyzed with the help of the Hirooka kinetics model.