HYDROGEN GAS DRIVEN PERMEATION THROUGH VANADIUM ALLOY VCR6TI5

Hydrogen gas driven permeation experiments were conducted with the van adium alloy VCr6Ti5 in the temperature range 423-1073 K and input pres sures 10(2)-10(3) Pa. Hydrogen permeation through this material was sh own to be limited by surface processes and permeated fluxes to be prop ortional to input pressures P more than P-1/2, in indicated ranges of temperatures and pressures, Sticking, (S), recombination coefficients, (b), and solubility constants, (C-S), in VCr6Ti5 have been extracted from the permeation experiments in the frame of a hydrogen permeation model, being limited by adsorption and desorption processes: S = 9.5 x 10(-5) exp(-40.2 kJ/mole/RT); b = 1.6 x 10(-21) molecules m(4)/atom(2 )s exp(-69.5 kJ/mole/RT); C-s = 1.1 x 10(-3) mole/m(3) root Pa exp(+14 .7 kJ/mole/RT). These values do not agree very well with the literatur e data obtained for other vanadium alloys, Thus, for more correct dete rmination of these values, the experimental results must be probably p rocessed taking into consideration the rate constants of transfers fro m surface into the bulk and emergence from the bulk onto the surface.