| Mg has a unity of large hydrogen storage capacity, the cheap price and other advantages, but its absorption and desorption hydrogen conditions are too severe and kinetics are poo. at present, the improvement for the magnesium-based hydrogen storage alloys also have inadequacies. Alloying is an important method to improve the storage properties of alloy hydrogen, in order to obtain the alloy which has good hydrogen storage properties. This article bring in high-entropy conception and preparate high-entropy alloy containing magnesium by the method of high-energy ball milling and preparate Sc-containing AB2type Laves phase hydrogen storage alloys by vacuum melting. Adopt X-ray diffraction analysis, scanning electron microscopy, absorption and desorption hydrogen as well as electrochemical performance test pairs of the prepared samples about their organizational structure, hydrogen storage and electrochemical properties and study these results. The results showed that:This paper designed a series of containing magnesium high entropy alloys and prepared by high-energy ball. The mixing enthalpy and mixing entropy were calculated in Miedema theoretical model. According to the test and calculation results, the relation between thermodynamic parameters and size parameters and phase structure were found. The results show that8%<5<10%,1<Ω<13, or-12<△Hmix<1.5,14%<△Rmax<18.5%when forming the single-phase solid solution alloy. So, theoretical calculation results can preliminary forecasting high entropy alloys containing magnesium, which provide a theoretical basis for later design alloys.Through common characterization methods such as XRD, SEM, TEM, researched the problem of the Mg in alloy solid fusion. We found that the single-phase organization could be formed when the Mg in the multi-component alloy. Meanwhile Mg element has not been found, and further proved that the high entropy alloys containing magnesium could prepared by mechanical alloying synthesis. Further studied hydrogen storage and electrochemical properties of the MgTiVNiM (M=Al, Co, Fe, Cu, Mn, Cr) alloy. Studies have shown that hydrogen storage thermodynamics and hydrogen storage and electrochemical capacity was low and cycle stability of high entropy alloys was poor. The maximum hydrogen storage capacity was1.1wt%(M=Fe) at573K and maximum electrochemical capacity was 170.9mAh/g.Micro structure and hydrogen storage properties of Sc0.8Zr0.1Y0.1Mn2-xNix(x=O～2) AB2-type hydrogen storage alloys were studied. The research results showed that the alloys were composed of Laves type main phase and minor ScNi phase and Y-riched phase as a second phase. The rare earth elements Sc and Y easily form intermetallic phase with Ni. With the increasing of the content of Ni element, the structure of the Laves phase changed from C14type to C15type. Thereinto, the alloy structure was Laves single-phase of C14-type when the value of x was0.0, while that was completely transformed into Laves single-phase of C15-type when the value of x was2.0. Substitution of Mn by Ni had a significant effect on the kinetics of the hydrogen absorption behavior and the equilibrium pressure of hydrogen absorbing PCT curve. As Ni element content increased, the hydrogen absorption kinetics and activation performance of the alloys gradually deteriorated and hydrogen absorption storage capacity decreased, but the hydrogen desorption temperature lower significantly and formation enthalpy of the hydride was reduced significantly (-18.72～-35.05kJ/mol) and the equilibrium pressure of hydrogen absorbing PCT rised. Although the maximum hydrogen capacity reached to2.18wt%at room temperature and after hydriding the lattice expansion rate△V/V was10.63～27.32%, the main phase of hydrides were still C14type phase and C15type phase and the phenomenon of phase transition and non-crystallizing were not found. |
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