WNbMoTa Refractory High-Entropy Alloys Fabricated by Laser Cladding Deposition

WNbMoTa refractory high-entropy alloys with four different tungsten concentrations ( = 0, 0.16, 0.33, 0.53) were fabricated by laser cladding deposition. The crystal structures of WNbMoTa alloys are all a single-phase solid solution of the body-centered cubic (BCC) structure. The size of the grains and dendrites are 20 μm and 4 μm on average, due to the rapid solidification characteristics of the laser cladding deposition. These are much smaller sizes than refractory high-entropy alloys fabricated by vacuum arc melting. In terms of integrated mechanical properties, the increase of the tungsten concentration of WNbMoTa has led to four results of the Vickers microhardness, i.e., H = 459.2 ± 9.7, 476.0 ± 12.9, 485.3 ± 8.7, and 497.6 ± 5.6. As a result, NbMoTa alloy shows a yield strength (σ_b) and compressive strain (ε_p) of 530 Mpa and 8.5% at 1000 °C, leading to better results than traditional refractory alloys such as T-111, C103, and Nb-1Zr, which are commonly used in the aerospace industry.