Activation Energy and Kinetics of First Hydrogenation in Ti_48.8Fe_46.0Mn_5.2Alloy Produced by Gas Atomization

The first hydrogenation behavior of the gas atomized Ti48.8Fe46.0Mn5.2 alloy was system-ically investigated. The as-received powder showed no hydrogen absorption due to the long air exposure before the hydrogenation tests. To overcome this, 5 passes of cold rolling were employed as an activation strategy. Cold rolling introduced cracks and defects that facilitated hydrogen diffusion, enabling the alloy to successfully absorb hydrogen. The influences of temperature, constant driving force, and hydrogen pressure on the first hydrogenation were evaluated. The results indicated that the first hydro-genation follows an Arrhenius behavior, with calculated activation energies of 69 and 57 kJ/mol H2. The observed difference in activation energies is likely associated with the variation of the driving force under constant pressure conditions. The pre-exponential factor (A) was found to be pressure-dependent, following the equation A = A₀ (P/P₀)1.8, where A₀ = 1.3 × 106 s⁻¹.