A comparative study on hydrogen storage properties of as-cast and extruded Mg-4.7Y-4.1Nd-0.5Zr alloys
A comparative study on hydrogen storage properties of as-cast and extruded Mg-4.7Y-4.1Nd-0.5Zr alloys
复制标题
铸态与挤压态Mg-4.7Y-4.1Nd-0.5Zr合金储氢性能对比研究
DOI：
10.1016/j.jpcs.2021.110483
复制
发表时间：
2021-12-07
影响因子：
4
通讯作者：
Zhou, D. W.
中科院分区：
文献类型：
--
作者：
Chen, J. N.;Zhang, J.;Zhou, D. W.
本文制备了铸态和挤压态Mg-4.7Y-4.1Nd-0.5Zr合金，并对其微观组织、储氢性能和催化机理进行了系统的研究。结果表明，铸态Mg-4.7Y-4.1Nd-0.5Zr合金主要由Mg、Mg 24 Y 5和Mg 41 Nd 5相组成，挤压态合金中的Mg 41 Nd 5相由于均匀化作用固溶于Mg基体中。加氢后，原位形成的稀土氢化物REHx纳米颗粒均匀分布在MgH 2表面，对后续镁基体的加氢和脱氢具有显着的催化作用。等温吸放氢动力学测试表明，Mg-4.7Y-4.1Nd-0.5Zr合金在两种状态下均表现出良好的吸氢动力学。与纯Mg相比，铸态和挤压态合金的脱氢反应表观活化能分别降低到114 kJ mol-1H 2和109 kJ mol-1H 2，这应归因于YH 2和NdH 2纳米粒子的催化作用。相比之下，挤压合金表现出更优异的脱氢动力学，并且在350 ℃下在15 min内可以释放超过6wt%的氢。第一性原理计算表明，稀土元素YH 2和NdH 2通过削弱H2分子内H-H键和MgH 2分子内Mg-H键的结合强度，提高了镁合金的储氢性能。
In this paper, the as-cast and extruded Mg-4.7Y-4.1Nd-0.5Zr alloys were prepared, and their microstructures, hydrogen storage properties and catalytic mechanisms were systematically studied. The results show that the ascast Mg-4.7Y-4.1Nd-0.5Zr alloy is mainly composed of Mg, Mg24Y5 and Mg41Nd5 phases, while the Mg41Nd5 phase in the extruded alloy is dissolved into Mg matrix due to homogenization. After hydrogenation, the in-situ formed nano-particles of rare earth hydride REHx are uniformly distributed on the surface of MgH2, which exhibit remarkable catalytic effects on the subsequent hydrogenation and dehydrogenation of Mg matrix. According to the isothermal hydrogen absorption and desorption kinetic testing, the Mg-4.7Y-4.1Nd-0.5Zr alloys in the two states both exhibit good hydrogen sorption kinetics. Compared with pure Mg, the apparent activation energies of dehydrogenation reaction of the as-cast and extruded alloys are reduced to 114 kJ mol- 1 H2 and 109 kJ mol- 1 H2, respectively, which should be ascribed to the catalytic roles of YH2 and NdH2 nano-hydrides. Comparatively, the extruded alloy presents a more excellent dehydrogenation kinetics, and it can release more than 6 wt% of hydrogen within 15 min at 350 degrees C. First-principles calculations reveals that the rare earth hydrides YH2 and NdH2 improve the hydrogen storage performance of Mg alloy by weakening the bonding strength of the H-H bond within H2 molecule and the Mg-H bond within MgH2.