Structural evolution of sputtered amorphous Fe_1-xC_x films for 0˙19 ≤ <i>x</i> ≤ 0˙49

Abstract

Abstract Sputtered amorphous Fe1-x Cx films with 0˙19 ≤ x ≤ 0˙49 have been studied. The mean magnetic moment per iron atom and the mean 57Fe hyperfine field decrease, while the mean 57Fe isomer shift increases, with increasing x up to a carbon content x r ≈ 0˙32, while they remain almost constant above x r. The crystallization mechanisms also change dramatically at x r; only the Fe7C3 carbide is observed above x r. All the experimental results are explained by assuming the existence of a two-phase domain in the amorphous state for x ≈x r, one phase being amorphous Fe-C with a constant carbon content x≈ x r, and the second an amorphous C phase with a negligible Fe content. The carbon content x r, is close to the maximum amount of carbon one can combine with iron to form a carbide: x = 0˙33, in Fe2C.