Design of Refractory High-Entropy Alloys to Reduce Weight and Cost ‎

High entropy alloys (HEAs) are a new class of multicomponent alloys in which the solid solution phase is formed as the main phase. Due to the variety of elements in their composition, these alloys have a good capacity to design alloys with desired properties such as lower weight and lower cost. In recent years, several studies have been conducted on refractory high- entropy alloys (RHEAs) for high temperature applications. However, refractory metals are generally very high density and somewhat expensive, so it is important to design the composition of these alloys so that the weight and cost of raw materials can be reduced. In this study, using calculations of thermodynamic and physical parameters, the composition of elements in W-Mo-Ta-Nb-V and W-Mo-Cr-Ti-Al RHEAs were optimized so that while reaching the solid solution phase, weight and cost are minimized. Finally, W10Mo27Cr21Ti22Al20 RHEA was obtained as the alloy with optimal composition in W-Mo-Cr-Ti-Al system and then melted and casted by VAM method. This RHEA contains a solid solution phase with BCC structure as the main phase and a small amount of Laves phase as a minor phase, which has a good agreement with the calculation results. SEM-BSE image of the as-cast RHEA exhibits a typical dendritic microstructure that the dendrites are enriched with elements with higher melting points such as W and Mo and interdendrites are enriched with Cr, Ti and Al.