Combined Centrifugal Casting–SHS Process of Refractory High-Entropy Nb–Ta–Hf–(Zr,Ti,Cr,V,Mm,Gd) Alloys

Cast refractory high-entropy alloys based on Nb–Ta–Hf, alloyed with 3d transition metals (Zr, Cr, V, Ti) and lanthanides (Gd, La + Ce), were successfully synthesized using a combined centrifugal casting–SHS method from thermite-type green mixtures containing target metal oxides. XRD and SEM analysis revealed that the primary phase in the synthesized alloys is a bcc solid solution. Introduction of alloying elements resulted in the formation of new structural precipitates, exhibiting bcc, fcc, and hcp structures, thus yielding complex multiphase microstructures.