Study of the evolution of the structure of a high-entropy Al<sub>20</sub>Ni<sub>20</sub>Co<sub>20</sub>Fe<sub>20</sub>Cr<sub>20</sub> alloy under the action of high pressures and temperature

Electron microscopic and X-ray studies of the structure of a high-entropy submicrocrystalline AlNiCoFeCr alloy of equiatomic composition obtained by arc melting were performed. The alloy consists of a substitutional solid solution with a packing of components corresponding to the B2 structure based on a distorted bcc lattice. The average grain size of the B2 phase is 120 nm. The stability of the alloy with increasing temperature was studied. When the alloy is heated to 1650oC and subsequent solidification, an increase in the grain size of the B2 phase and the separation of several phases with different morphologies along the grain boundaries are noted in the structure. The effect of high pressure on the structure of the alloy after quenching from the liquid phase was studied. The structure of the sample obtained upon solidification at a temperature of 1650°C under a pressure of 5 GPa is different from the structure of the alloy obtained at a temperature of 1650°C by arc melting. Under thermobaric conditions, a structure of mixed phases of A1 and A2 types is formed in the alloy. The alloy has high hardness, the value of which, depending on the selected production conditions, varies from 4.8 to 5.5 GPa.