Microstructure features of high-entropy equiatomic cast AlCrFeCoNiCu alloys

The structural and phase transformations that take place in the cast high-entropy equiatomic alloy AlCrFeCoNiCu after solidification, homogenizing heat treatment, and cooling have been studied. Analytical transmission microscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, and X-ray diffraction analysis were used to conduct the studies. The elastic modulus, nano-, and microhardness have been measured. The alloy decomposition has been found to occur with the precipitation of no less than six nanoscale phases with different morphologies, structures (A2, B2, L12), and chemical compositions. All the nanophases are multicomponent solid solutions enriched with several elements, which indicates the pronounced elemental and phase nanomodulation over the alloy volume.