W _x NbMoTa Refractory High-Entropy Alloys Fabricated by Laser Cladding Deposition

Abstract

W _x NbMoTa refractory high-entropy alloys with four different tungsten concentrations ( x = 0, 0.16, 0.33, 0.53) were fabricated by laser cladding deposition. The crystal structures of W _x NbMoTa 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 W _x NbMoTa has led to four results of the Vickers microhardness, i.e., H _v = 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.