Hydrogen transport and trapping in the GlidCop Al25 IG alloy

The hydrogen properties of permeability, diffusivity and Sieverts' constant in the GlidCop Al25 IG alloy have been experimentally evaluated by using the gas permeation technique. The experimental temperature range used has been from 573 K to 793 K and the high purity hydrogen loading pressures from 103 Pa to 1.5 x 105 Pa. The resultant diffusive transport parameters are a permeability of φ (mol m-1 Pa-1/2 s-1) = 5.87 x 10-7 exp(-80.6 kJ mol-1/RT), a diffusivity of D (m2 s-1) = 5.70 x 10-5 exp(-76.8 kJ mol-1/RT) and a Sieverts' constant of Ks (mol m-3 Pa-1/2) = 6.01 x 10-3 exp(-3.7 kJ mol-1/RT). The resultant trapping parameters are a trap density of Nt = 3.1 x 1022 m-3 and a trapping energy of Et = 75.4 kJ mol-1. The presence of ultrafine Al2O3 particles in this material has been demonstrated to affect enormously the hydrogen isotope transport behaviour in comparison to the corresponding base material (Cu) and other copper alloys. Hydrogen trapping phenomenon has become more noticeable in the lower temperature range, yielding an exothermic absorption of hydrogen below 688 K and a decrease in the effective hydrogen diffusivity.