Design of heterogeneous structure for enhancing formation quality of laser-manufactured WTaMoNb refractory high-entropy alloy

Abstract

WTaMoNb based refractory high-entropy alloys (RHEAs) are promising as the structural materials at ultrahigh temperatures, while the poor processability limits their application. In this work, WTaMoNb RHEA with different thickness was fabricated by laser cladding using the spherical spray-granulated powder. Dual heterogeneous structure (HS) was in situ formed through introducing C from the spray-granulated powder, and constructed FCC skeleton structure in BCC matrix with dispersive FCC hard particles. The HS was conductive to reduce property anisotropy of WTaMoNb RHEAs, enhancing the resistance to crack and ensuring high formation quality. Laser remelting after cladding triple layers further refined the microstructure, improved the cracking resistance, and increased the hardness, fracture toughness and elastic properties. The sample after remelting showed superior mechanical properties and wear resistance, including harness of 653 HV, fracture toughness of 4.9 ± 0.8 MPa·m1/2 and the ratio of recovery elastic energy of 18.8 %, and low wear rate of 1.0 × 10–5 mm3/(N·m), which mainly attributes to the formation of dual HS. This work provides a novel strategy to fabricate WTaMoNb RHEAs with high formation quality, good mechanical properties and high wear resistance.