Tuning crystal structure by composition in Al–Cr–Fe–Ni multi-principal component alloy films

Abstract

Multi-principal component alloys (MCAs), especially high entropy alloys, provide us a novel platform for material design aiming to achieve certain or multifunctional properties by tuning crystal structure. However, tuning crystal structure by composition will take much more time and more cost compared with the traditional binary and ternary alloys. Here, we provide a more effective method to tune crystal structure of MCAs by composition. Using radio frequency magnetron sputtering, single-phase Al–Cr–Fe–Ni multi-principal component alloy films (MCFs) with different composition fluctuations were deposited on silicon substrates. The effects of composition on the crystal structure of Al–Cr–Fe–Ni MCFs were investigated in detail. The results indicate that Al and Cr tend to stabilize bcc crystal structure, while Ni and Fe tend to stabilize fcc crystal structure of Al–Cr–Fe–Ni MCFs. Factor analysis (FA) reveals the order of stabilizing effect of each principal element on the bcc structure of Al–Cr–Fe–Ni MCFs. Magnetic measurement shows a close relationship of structure and magnetic properties for Al–Cr–Fe–Ni MCFs. The superparamagnetism behaviors originated from the small grain size of the Al–Cr–Fe–Ni MCFs, while the antiferromagnetism stemmed from the lattice contraction induced by the fcc-bcc transiton. All the results show that MCFs deposited by magnetron sputtering is a effective platform to tune crystal structure and properties by composition, which will surely help us in new MCA design.