REACTION-KINETICS OF N2 ABSORPTION BY SM2FE17

The kinetics of N2 absorption by Sm2Fe17 were investigated using volum etric and gravimetric measurements under ultrahigh vacuum and high N2 pressures. The kinetic results obtained suggest that the rate-controll ing step in the N2 absorption by Sm2Fe17 changes from N2 dissociation on the alloy surface during the initial stage to N diffusion in the bu lk as the reaction proceeds. The activation energy for the diffusion w as found to be in the range 100-163 kJ (mol N2)-1. Pretreatment of the alloy by H-2 gas decreases the initial rate, but increases the maximu m amount of N absorbed in the equilibrium state.