A catalytic mechanism investigation of TiF on hydriding/dehydriding properties of MgCuNi alloy.

In this research, MgCuNi- wt% TiF ( = 0, 2, 4, 6, 8) alloys were synthetized ball milling and the catalytic mechanism of TiF on hydrogenation and dehydrogenation of MgCuNi was studied. The microstructure, hydriding/dehydriding kinetics and thermodynamics of the alloys were discussed in detail. The TiF catalyzed alloys have faster hydriding/dehydriding kinetics and lower thermodynamic stability. After hydrogen absorption and desorption, TiF decomposes into TiH and MgF. TiF, TiH and MgF promote to forming crystal defects, dislocations, grain boundaries and nanocrystals which are advantageous to speeding up the rate of hydrogen absorption and desorption. The dehydrogenation activation energy (de) and dehydrogenation enthalpy Δ(de) are reduced to 81.462 from 116.767 kJ mol and 72.456 from 93.372 kJ mol respectively by 6 wt% TiF. An appropriate amount of TiF can improve the hydriding/dehydriding kinetics and thermodynamics of MgCuNi.