High-Throughput Synthesis and Characterization of Thin Film High Entropy Alloys Based on the Fe-Ni-Co-Cu-Ga System

Abstract

High entropy alloys offer a new approach in alloy design by combining multiple elements around equiatomic proportions; relatively simple crystal structures may be obtained and promising properties have been reported. However, there is a major challenge to validate complex phase equilibria predictions for such multifold chemistries, and subsequently, to optimize composition within a selected alloy system. In the present case, high-throughput techniques were employed for the synthesis and characterization of thin films of varying composition around the equiatomic FeNiCoCuGa composition. Continuous thin films were deposited by modified molecular beam epitaxy (MBE) technology and annealed in a reducing atmosphere. Subsequently, the thin films were characterized by EDS, SEM and XRD. The results allow isothermal and isochemical sections of the quinary phase diagram to be drawn, revealing domains of three disordered crystalline phases, as well as mapping of their relative concentrations. General trends of the effect of the constituent elements on the phase concentrations and domain of existence can easily be accessed. These results are compared with data obtained from bulk samples.