Hydrogen Absorbability Improvement of Ti-based Quasicrystal with Magnesium Powder Synthesized by Mechanical Alloying Process

Hydrogen is an interesting choice as alternative energy due to promising properties: clean, environmentally friendly, as well as being one of the most exuberant elements on earth. Nowadays, various materials and methods have been proposed as hydrogen storage by many researchers. Ti-based quasicrystal alloy (Ti-Zr-Ni) was reported as excellent hydrogen storage materials with 140 sites of interstices, which are higher than the number of sites found in other crystals. As well as magnesium (Mg), is known as one of the most famous hydrogen reservoir materials due to the lower cost and good stability when reacting with hydrogen. However, the enthalpy and temperature hydrogen absorption were quite high of MgH2 and reports on Ti-Zr-Ni-Mg alloys were limited. In order to improve the capacity of hydrogen storage, this research has been conducted by adding Mg into the Ti-Zr-Ni quasicrystal alloy as Ti₄₃Zr₃₈Ni₁₇Mg₂. The samples were mixed by mechanical alloying under two conditions (1) 600 rpm with 20 h milling time and (2) 630 rpm with 30 h milling time. The samples were annealed to form quasicrystal. The gas-phase hydrogen absorption has been observed by pressure composition isotherm (PCT) measurements. Morphology and structural analysis were analyzed by XRD and SEM. The measurements showed the maximum capacity achieved by 600 rpm with 20 h milling time. The hydrogen-to-metal (H/M) of the former condition has revealed a higher capacity of hydrogen storage with H/M = 1.99 than the latter condition with H/M = 1.58.