Activation of Ti-Fe-Cr alloys containing identical AB2 fractions
Activation of Ti-Fe-Cr alloys containing identical AB2 fractions
复制标题
DOI：
10.1016/j.jallcom.2021.158876
复制
发表时间：
2021-02-01
影响因子：
6.2
通讯作者：
Suh, Jin-Yoo
中科院分区：
文献类型：
--
作者：
Kim, Hayoung;Faisal, Mohammad;Suh, Jin-Yoo
TiFe基合金是一种在室温下工作的固态储氢材料。当前的研究提出了一种系统的方法，通过使用第二AB（2）相来解决活化问题（第一次加氢的困难），这是TiFe合金实际应用的主要障碍之一。基于Ti-Fe-Cr三元相图，设计了含80at%Ti（Fe，Cr）（AB相）和20at%Ti（Fe，Cr）（2）（AB（2）相）的Ti-Fe-Cr合金，在保持固定相分数的同时，系统地改变AB相和AB（2）相中Cr的含量。当总铬浓度高于9.7at%时，实现RT下的活化。对各个相的活化特性的分析表明，AB（2）相容易吸收氢，从而引发AB + AB（2）合金的活化。值得注意的是，较高的Cr浓度使得AB相能够在活化过程期间在RT下吸收氢，尽管动力学比共存的AB（2）相慢得多。从压力-组成等温线的平衡氢压力降低作为Cr浓度的增加，表明Cr稳定的Cr。增加的氢化物稳定性也可促进AB和AB（2）相中初始氢化物形成的动力学。在室温下容易活化和在工作压力范围内具有最大可逆容量的条件下，可以设计Ti-Fe-Cr合金的最佳成分。(C)2021由爱思唯尔公司出版
TiFe-based alloys are solid-state hydrogen storage materials operated at room temperature (RT). The current study presents a systematic approach for solving the activation issue (difficulty in the first hydrogenation), one of the major obstacles to the practical application of TiFe alloys, via the use of a secondary AB(2) phase. Based on the Ti-Fe-Cr ternary phase diagram, Ti-Fe-Cr alloys containing 80 at% Ti(Fe,Cr) (AB phase) and 20 at% Ti(Fe,Cr)(2) (AB(2) phase) were designed; the Cr concentrations in the AB and AB(2) phase were systematically varied while maintaining fixed phase fractions. Activation at RT was achieved when the overall Cr concentration was higher than 9.7 at%. Analysis of the activation characteristics of the individual phases revealed that the AB(2) phase readily absorbed hydrogen, thereby initiating activation of AB + AB(2) alloys. Notably, higher Cr concentrations enable the AB phase to absorb hydrogen at RT during the activation process, although the kinetics are much slower than that of the co-existing AB(2) phase. The equilibrium hydrogen pressures from the pressure-composition isotherms decrease as the Cr concentration increases, indicating that Cr stabilizes hydrides. Increased hydride stability may also promote the kinetics of the initial hydride formation in both the AB and AB(2) phases. An optimal composition for Ti-Fe-Cr alloys can be designed given the conditions of easy activation at RT and maximum reversible capacity within an operating pressure range. (C) 2021 Published by Elsevier B.V.