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. (C) 2014 Elsevier B.V. All rights reserved.