Study of change in the structure and properties of high-entropy alloys during thermal and thermomechanical processing

Multicomponent alloys without a base element, also known as high-entropy alloys, are of great interest for research. This paper studies the microstructure of the Fe₂₀Ni₂₀Co₂₀Cu₂₀Al₂₀ alloy in a cast, annealed and deformed state, as well as its mechanical properties and hot deformation ability. This alloy is one of the typical representatives of the high-entropy alloy family. Samples were melted in a vac induction furnace in an argon atmosphere, and then cast into a copper mold. Differential scanning calorimetry results were used to determine the solidus temperature. Homogenization annealing of cast samples was carried out in a high-temperature batch furnace in air. The alloy microstructure was studied by scanning electron microscopy and X-ray diffraction. Electron microprobe analysis using energy dispersive X-ray spectroscopy was used to determine the chemical composition of phases formed. It was shown that crystallization results in the formation of three solid solutions, one with a BCC and two with a FCC crystalline structure. Mechanical properties were studied using uniaxial compressive strength and hardness tests. Deformation tests were carried out on a DIL805A/D quenching and deformation dilatometer and a Gleeble 3800 thermal-mechanical physical simulation system at temperatures of 900 — 1100 °C and strain rates of 0.1—10.0 s^—1 for a true strain degree of up to 1. Optimal homogenization annealing modes for the typical representative of high-entropy alloys, and optimal deformation modes were selected to obtain high mechanical properties.

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