Absorption kinetics of nitrogen + tantalum system

The dependence of the absorption rate on temperature is studied for a single-crystal tantalum wire, and is compared with those for polycrystal wires and ribbons. Two processes of absorption of nitrogen in tantalum are found. In the first process absorption occurs at boundaries of crystal grains and is observed for polycrystal ribbons with surface of the (311) planes; the activation energy of absorption is 1.9 eV/2-atoms. The second process is observed for crystallized or sufficiently flashed wires. In this process atoms chemisorbed on the surface are directly absorbed into the bulk at their absorption sites; the activation energy of absorption is 4.0 eV/2-atoms, which is larger than that of diffusion of nitrogen in tantalum.