Large-scale production of BCC solid solution hydrogen storage alloy

Abstract

In this work, 52Ti–12V–36Cr + 4 wt% Zr alloy was synthesized at laboratory and large scales for comparative analysis of the hydrogen storage performance. A 5 g and 2 kg BCC solid solution alloy is synthesized by arc melting and induction melting, respectively. Crystal structure investigation revealed that both samples crystallized into a primary BCC phase and a secondary laves phase with no significant difference in the overall XRD pattern. First hydrogenation studies showed the maximum hydrogen storage capacity of arc melted alloy (AM) and induction melted alloys (IM) alloy are 3.5 wt% and 2.9 wt%, respectively, at room temperature under a hydrogen pressure of 20 bar. No visible incubation period was observed in AM alloy, whereas IM alloy showed an incubation period of 32 min with slower kinetics. The appearance of the incubation period and sluggish kinetics can be due to the formation of a passive layer during induction melting that changes the hydrogen sorption properties. The microstructural analysis confirmed the carbon contamination from the induction melting crucible and formation of the TiC phase in the matrix, which was absent in the AM alloy, significantly affecting hydrogen storage capacity. The enthalpy and entropy of 2 kg alloy are −65.84 kJ/mol and 188.92 J/mol-K.