Microstructure and oxidation behavior of Alx(CrFeCoCuNi)100–x composition spread thin film

Abstract

Al_x(CrFeCoCuNi)_100–x thin film was fabricated by the magnetron co-sputtering. The microstructures of the high entropy alloy (HEA) film before and after the high temperature oxidation at 950 °C for 1.5 h were investigated. A combinatorial library of the film with the concentration of Al ranging from 10 to 40 at % is achieved. The structure of the film transforms from face-centered cubic (FCC) to body-centered cubic (BCC) with the increasing Al content. Three distinct regions of oxides are identified across the oxidized film from the low to high Al content regions. The critical Al concentration for the establishment of a passivating Al₂O₃ scale is determined.