La_5Mg_(95-x)Ni_x(x=5、10、15)合金的显微组织、储氢热力学和动力学性能（英文）

Microstructure, hydrogen storage thermodynamics and kinetics of La_5Mg_(95-x)Ni_x(x=5, 10, 15) alloys

研究Ni含量对La_5Mg_(95-x)Ni_x(x=5、10、15)三元合金的显微组织、热力学和动力学性能的影响。采用XRD和SEM探索合金的相和组织的变化情况,采用自动Sievert设备测试合金吸放氢性能曲线和PCI曲线。研究表明,随着Ni含量的增加,合金的储氢动力学性能得到提高,但是合金的储氢容量有所下降。三种成分的合金中,La_5Mg_(80)Ni_(15)合金表现出最低的放氢活化能以及最高的吸放氢速率,其放氢活化能为57.7kJ/mol。通过测定合金PCI曲线和van’tHoff方程发现,随着Ni含量的增加,合金的热力学性能先提高后降低,其中La_5Mg_(85)Ni_(10)表现出最优异的热力学性能,其焓和熵的数值分别为-72.1 kJ/mol和-123.2J/(mol·K)。

The microstructure, hydrogen storage thermodynamics and kinetics of La5Mg95-xNix (x=5, 10, 15) ternary alloys with different Ni contents were investigated. The evolutions of the microstructure and phase of experimental alloys were characterized by X-ray diffractometry and scanning electron microscopy. The hydrogen storage kinetics and thermodynamics, and P-C-I curves were tested using a Sievert apparatus. It is found that increasing Ni content remarkably improves hydrogen storage kinetics but reduces the hydrogen storage capacity of alloys. The highest hydrogen absorption/desorption rate is observed in the La5Mg80Ni15 alloy, with the lowest hydrogen desorption activation value being 57.7 kJ/mol. By means of P-C-I curves and the van’t Hoff equation, it is determined that the thermodynamic performance of the alloy is initially improved and then degraded with increasing Ni content. The La5Mg85Ni10 alloy has the best thermodynamics properties with a hydrogenation enthalpy of -72.1 kJ/mol and hydrogenation entropy of -123.2 J/(mol·K).