Abstract
The determination of a material's microstructure is of great importance in understanding its properties, and this of course is no exception for the newly developed high-entropy alloys. The composition is a principal factor in dictating the microstructure formed. It is well known that certain elements can stabilize particular phases in conventional alloys. For convenience, elements which can influence a material's properties in the same way, such as stabilizing a particular phase, can be made to be 'equivalent' to a given reference element. In the present study, the phase forming equivalents of elements in the high-entropy Al x Co y Cr z Cu 0.5 Fe v Ni w alloy system were investigated by varying the molar ratios of each element (lettered subscripts) within a range of 0 to 3.5, while maintaining the other elements and Cu at 1 and 0.5, respectively. It was shown by X-ray diffraction (XRD) that Ni and Co are FCC stabilizers, Al and Cr are BCC stabilizers and Fe is neutral in the solid-solution phases that form. From energy dispersive spectroscopy chemical analysis and XRD, it was determined that 1.11 Co FCC is equivalent to Ni FCC for the FCC stabilizers, and that 2.23 Grace is equivalent to Al BCC for the BCC stabilizers. A 45-55 % rule is found for judging whether a phase will be FCC or BCC, wherein a phase has an FCC structure if the % Co FCC is greater than 45 at. % and a BCC structure if the % Cr BCC is greater than 55 at. %. © Lavoisier.