Hydrogen permeation characteristics of rolled V85Al10Co5 alloys

Thin sheets of V85Al10Co5 alloy were produced by a thermo-mechanical treatment consisting in successive hot rolling, cold rolling steps and annealing treatment at high temperature followed by either air cooling or water quenching. Though the values of hydrogen permeability measured for these sheets were significantly reduced as a consequence of the rolling process, the annealing treatment restored almost the hydrogen permeation properties to those of the alloy in the cast condition. EBSD analyses suggested that the post-annealing treatment performed at 1100 °C for 3 min after cold rolling induced a recrystallization of the grains resulting in a preferred orientation along the {002} planes. For the sample annealed and water quenched, the value of the hydrogen flux reached about 45 ml/cm2.min, which is more than twice the value of the flux obtained for thin foils of Pd alloys tested under identical conditions.

► Thin membranes of V–Al–Co alloy have been prepared by thermo-mechanical treatment. ► The hot and cold rolled alloys were annealed at high temperature for a short time. ► The hydrogen permeability shows a dependence on the cooling rate after annealing. ► Fast cooling rates induced by water quenching enhanced the hydrogen permeability. ► The study demonstrates the effect of low angle grain boundaries on these properties.