| Abstract Scope |
Refractory alloys are promising for high-temperature applications because of their high strength at elevated temperatures, high thermal conductivity, low thermal expansion coefficient, and operability under oxidizing conditions. One hundred twenty-five refractory high entropy alloys (RHEAs) have been designed to exhibit single BCC phase at elevated temperatures, target yield strength (>200 MPa) at 1300°C, density (<9 gr/cc), thermal conductivity (>9 W/mK), linear thermal expansion (<2%) between ambient and 1300 ℃, and narrow solidification range for additive manufacturability. Designed compositions are synthesized with high-throughput vacuum arc melting and characterized via electron microscopy (SEM/EDX), XRD, Vickers microhardness, nanoindentation, compression, tension, thermal transport, and thermal expansion experiments. In as-cast state, all samples had BCC phase with dendrites. Homogenization heat treatments at 1800°C and 1925°C are performed based on diffusion calculations centered around the compositional difference and dendrite arm spacing. Compression/tension experiments are then performed at high temperatures to compare with the predicted high-temperature properties. |