Effect of Ar Gas Pressure on Morphology and Structure of Nonequilibrium Fe–Cu Alloys Produced by rf Sputtering

Abstract

Fe_1−xCu_x alloy films sputter-deposited on water-cooled substrates under Ar gas pressures, P_Ar=8.9 and 0.23 Pa, were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction measurements. The SEM and TEM studies show that the alloy films made under P_Ar=8.9 Pa have a columnar structure with a grain size of about 20 nm, while those made under P_Ar=0.23 Pa have a fibrous structure with a grain size of about 10 nm. The primary solid solutions of both bcc and fcc phases are extended in the Fe-rich and Cu-rich regions, respectively in contrast to no solid solution in the equilibrium phase diagram. In the Fe_1−xCu_x alloys made under a high P_Ar, moreover, the single phase regions more widely extend and the oxide phase, CuFeO₂, coexists.