Research progress of interactions between amorphous alloys and hydrogen

Abstract

Amorphous alloys are a group of novel mechanical and functional materials that possess remarkably improved properties, such as mechanical property, wear property, anti-corrosion property, magnetic property and catalytic property, compared with those of their crystalline counterparts. The interactions between amorphous alloys and hydrogen can lead to various interesting physical and chemical phenomena, and also important applications. Typically, some amorphous alloys can store more hydrogen with faster kinetics than their crystalline counterparts due to the disordered atomic structures, which make them promising candidates for hydrogen storage. Hydrogen induced optical transformation in amorphous alloy film with thickness on a nanoscale makes them suitable for developing optical switchable windows. Hydrogen could be used as a sensitive probe to study the atomic structures of amorphous alloys. Amorphous alloys, whose structures are similar to defects in crystalline alloys (vacancies, dislocations, boundaries, ect.), are a group of suitable objects to study the interactions between hydrogen and defects. Amorphous alloys are also promising membranes materials for industrial hydrogen gas purification. Micro-alloying by hydrogenation could enhance the plasticity and glass-forming ability of amorphous alloy.In this review, recent research progress of interactions between amorphous alloys and hydrogen are summarized from two main aspects: fundamental research and practical applications. In the aspect of fundamental research, we firstly review the recent study on hydrogen in the amorphous alloy, including the hydrogen concentration and distribution, hydrogen occupancy type and geometric size, hydrogen diffusion and thermodynamics and other relevant physical and chemical issues. Secondly, the studies on the effects of hydrogenation on thermal stability, magnetic property and internal friction of amorphous alloys, together with some discussion on the corresponding mechanisms are summarized. Thirdly, hydrogen embrittlement of amorphous alloy and the corresponding prevention techniques, together with the studies of the interactions between hydrogen and defects in crystalline materials such as vacancies, dislocations and boundaries in material, are also involved. In the aspect of practical applications, we firstly review recent advances in amorphous hydrogen storage alloys, focusing on transition metal based amorphous alloys and Mg based alloys. Secondly, amorphous alloy films for hydrogen purification, hydrogen sensors and optical switchable windows are reviewed. Thirdly, some positive influences introduced by hydrogenation on amorphous alloys are discussed, typically on enhancing plasticity and glass-forming ability. Besides the above, hydrogen induced amorphization on crystalline alloy, the use of amorphous alloy for preparing nanocrystalline hydrogen storage materials, and using hydrogenation to crack bulk amorphous alloys to produce amorphous alloys powders are also discussed. In the last section of this review, we try to give our own viewpoint of the future perspectives of relevant researches and applications of interactions between hydrogen and amorphous alloys.