Senary refractory high-entropy alloy CrxMoNbTaVW

This paper demonstrates that a senary refractory high-entropy alloy CrxMoNbTaVW can be tailored over a certain range of Cr content with the BCC structure for different microstructures and physical properties, assisted by CALPHAD simulations. Microstructure characterizations are performed using X-ray diffraction and scanning electron microscopy. Chemical micro-segregation during solidification predicted using the Scheil model generally agrees with the experimental results. The lattice constant, density, and Vickers' micro-hardness of the high-entropy alloy samples in the as-cast state are measured and discussed. For CrxMoNbTaVW, x=2.0 case appears exceeding the upper limit of maintaining a single BCC phase HEA, determined by the XRD patterns. The elemental dependence of the mixing thermodynamic properties (entropy, enthalpy and Gibbs energy) in BCC phase in the senary system is analyzed. The calculated entropy of mixing and enthalpy of mixing for CrMoNbTaVW are 14.7 J/K/mol and -662.5 J/mol respectively. (C) 2015 Elsevier Ltd. All rights reserved.