Prospective compositions of heat-resistant high-entropy alloys for foundry production

The work investigates promising compositions of high-entropy alloys (HEAs) based on the FeNiCrCuAl and FeNiCrCuMn systems, which have the potential for use as heat-resistant materials in foundry production. It is shown that the use of a specially designed vacuum medium-frequency induction furnace allows obtaining high-quality ingots with active mixing of the melt and temperatures up to 1800°C. The thermodynamic parameters (entropy and enthalpy of mixing, atomic radii, electronegativities, VEC, Ω parameter) were calculated, on the basis of which the phase composition was predicted. X-ray phase analysis confirmed the formation of solid solutions with FCC and BCC lattices, an ordered B2 phase (of the NiAl type). In addition to phase analysis and structural study, the thermophysical properties (melting and crystallization heats, liquidus-solidus temperatures) and elastic properties of alloys in a wide temperature range were investigated by the dynamic mechanical analysis (DMA) method. The dependences of the elastic modulus and the tangent of the mechanical loss angle on temperature were established. The heat resistance of alloys (at 900 ºC and 1000 ºC) was assessed, which showed high stability of the structure of high-entropy alloys in an oxidizing environment. The casting properties of the experimental alloys – fluidity and linear shrinkage – were studied using spiral and U-shaped samples, which allowed comparing them with the indicators of cast irons and steels. The fluidity of high-entropy alloys of the FeNiCrCuMn system is lower, and that of alloys of the FeNiCrCuAl system is higher compared to standard steels (G25, GX10CrNiMn18-9-1. Thus, the results of the study confirm the feasibility of using alloys of the FeNiCrCuMn and FeNiCrCuAl systems as heat-resistant casting materials of a new generation.