Microstructure of a near-equimolar refractory high-entropy alloy

The microstructure of a promising equimolar refractory high-entropy alloy containing Ti, Zr, Hf, Nb and Ta has been investigated after arc melting and induction techniques. The high-entropy alloy displays a fully disordered bcc crystal structure. At the nanoscopic scale, the observed dislocations appear mainly patterned in sub-grain boundaries in the solid solution. At the mesoscopic level and following the cooling rate, the solidified microstructure is different: the alloy exhibits a dendritic structure with the presence of Ti, Zr and Hf-rich microsegregations in the interdendritic zones for the slowest cooled parts, whereas it is fully homogenized in the regions for which the cooling rate is intense.