Abstract:The electron-stimulated desorption was used to measure the surface diffusivity of atomic deuterium on clean and boron-modified Ni₃(Al, Ti)(110) surfaces. Boron dosing was performed using a solid-state boron ion source. Earlier studies showed that boron dissociates water readily at temperatures as low as 130K and that the resulting atomic hydrogen is bound to the surface strongly. The surface diffusion coefficient of atomic D on 0.05 monolayer boron-modified surface was measured to be about 10 times smaller than that on the clean surface. This slower diffusion of atomic hydrogen may explain why boron improves the ductility of polycrystalline Ni₃Al in moist environments.

Key words: surface diffusion; deuterium; hydrogen; Ni₃Al