Effect of Ti on defects in Nb-Mo-Ta-W high-entropy alloy prepared by laser metal deposition

Abstract

The Nb-Mo-Ta-W series refractory high-entropy alloys with composition recombination design were manufactured by laser metal deposition process. The phase structure, defects and microstructure of（NbMoTa）90W10 and（NbMoTaTi）90W10 high-entropy alloys were characterized and analyzed by X-ray diffraction and scanning electron microscope. The tensile properties of the two alloys were tested at room temperature by multifunctional mechanical testing machine. The results showed that both（NbMoTa）90W10 and（NbMoTaTi）90W10 high-entropy alloys are single-phase body centered cubic structures. Ti element forms a "liquid film" at the grain boundaries in Nb-Mo-Ta-W series alloy, which can effectively suppress intergranular cracks. Due to the reduction of metallurgical defects and the lattice distortion effect, the mechanical property of（NbMoTaTi）90W10 high-entropy alloy at room temperature is improved, and the yield strength reaches 1156 MPa.

Keywords

• laser metal deposition
• refractory high-entropy alloy
• liquid film
• metallurgical defects