Structural evolution of yttrium nanolayer inserted in FeNi/Y nanomultilayered film

Abstract The FeNi/Y nanomultilayered films with different Y layer thickness ( t Y ) were synthesized by magnetron sputtering. The structural evolution of Y nanolayer with increase in t Y was investigated. When t Y was less than 2 nm, Y layers transformed to fcc structure under the template effect of FeNi layers and grew epitaxially with FeNi. With t Y of 3 nm, Y layers could not maintain the epitaxial growth, but present a transient amorphous state. As t Y further increases to 4 nm, Y layers transformed into the stable hcp structure. The microstructural evolution sequence of Y layers was fcc→amorphous→hcp structure, which could be explained by a thermodynamic model.