Effects of Fe and Cr on the microstructure and mechanical properties of FexCr72−xNi14Al14 high-entropy alloys

Abstract

Cobalt-free lightweight FexCr(72−x)Ni14Al14 (x = 34, 36; at%) high-entropy alloys were designed and prepared in this study to determine the effects of Fe and Cr content variations on the microstructure and mechanical properties of the alloys. Both alloys were prepared from pure metals using a vacuum arc melting furnace. The microstructures of the alloys were characterized using various analytical methods and the macroscopic compressive mechanical properties and microscopic creep properties were investigated. Both alloys were composed of a disordered α(Fe-Cr) body-centered cubic matrix and ordered (Ni-Al) B2 nanoparticle precipitates, with the differently sized nanoparticle precipitates and micron grains forming a four-stage layered structure. The alloys exhibited excellent compressive properties with a maximum yield strength of 1378 MPa, compression ratio of 34.1 %, and high specific yield strength of 210 kPa·m3/kg. Dense geometrically necessary dislocations (GNDs) were observed in the grains of the two as-cast alloys. GND was the main deformation mechanism in the early stages of creep, and the GNDs and B2 precipitated phase became obstacles to dislocation movement, which improved the creep resistance of the alloys. Excellent mechanical properties and good economy have great attraction in structural materials