Hydrogen generation from pure water using Al–Sn powders consolidated through high-pressure torsion

Al-Sn binary alloys are fabricated by powder consolidation using high-pressure torsion (HPT). The HPT-processed samples are immersed in pure water and hydrogen generation behavior is investigated with respect to the imposed strain through the HPT processing at a selected temperature in the range of 297–333 K. Microstructures of HPT-processed alloys are analyzed by x-ray diffraction, transmission electron microscopy (TEM), electron probe microanalysis (EPMA) and electron back scattered diffraction (EBSD) analysis. Results show that it is important to add more than 60 wt% of Sn to activate hydrogen generation from the Al-Sn alloys in pure water. TEM and EBSD images reveal significant grain refinement while EPMA results exhibit homogenous distribution of elements achieved by HPT. The grain refinement and distribution of elements attained by HPT processing influence greatly the hydrogen generation rate and yield of the alloys. An Al-80 wt% Sn alloy with an average grain size of ∼270 nm exhibits the highest hydrogen yield and generation rate in pure water at 333 K.