Effects of annealing in Be/W and Be/C bilayers deposited on Si(001) substrates with Fe buffer layers

•Be/W, Be/C layers deposited by TVA on Si substrate with thin sputtered Fe buffers.•Fe films were hydrogenated (300°C); Be/W and Be/C were annealed in vacuum (600°C).•Increase of oxidation near the surface; the hydrogenation reduces oxidation.•The annealing induces high interatomic diffusion all over the structure.•Mixed phases are formed by annealing: Fe–Be, Fe–C; no Fe–W phases are evidenced.