Single-Phase Medium- to High-Entropy Alloys Developed by a Simple Thermodynamic Approach

We have designed and fabricated four previously unexplored body-centered cubic (BCC) single phase VCrMo, VCrMoNb, VCrMoTa, and VCrMoNbTa refractory medium- to high-entropy alloys using a simple thermodynamic approach. The effectiveness of this approach was further theoretically and experimentally demonstrated by using calculation of phase diagrams (CALPHAD) simulations and arc-melting synthesis, respectively. The elemental segregation could be successfully predicted by the Scheil–Gulliver model. All the samples exhibited as-cast dendritic microstructures with high microhardness values. Finally, a general route is proposed to design equiatomic and non-equiatomic medium- to high-entropy alloys based on the rational selection of a binary system and by adding a premeditated amount of principal elements using a simple thermodynamic parameter.