A novel B₄C nanoparticle-reinforced WMoTaTi refractory high-entropy alloy: Microstructural optimization and enhanced mechanical properties via laser powder bed fusion

The promising application potential of refractory high-entropy alloys (RHEAs) in high-temperature extreme environments is restricted by the difficulty in their preparation, especially for the components with complex shapes. Laser powder bed fusion (LPBF), as an advanced additive manufacturing technique, has been employed for fabricating RHEAs; however, their mechanical properties were still limited. In this study, different contents of B₄C nano-ceramic particles were introduced to reinforce WMoTaTi refractory high-entropy alloys via LPBF, and the effects of B₄C on the microstructure and mechanical properties of the alloys were systematically investigated. Room-temperature compression tests demonstrated that the yield strength of the alloy was markedly increased from 1062 MPa to 1558 MPa with the addition of 1.0 wt% B₄C, while a high strength of 536 MPa was achieved at testing temperature of 1200 °C, indicating exceptional high-temperature properties. Through a comprehensive analysis, the multiple strengthening mechanisms were discussed to understand the strengthening effect of B₄C particles. This study not only provides new experimental evidence for the strengthening of RHEAs by nano-ceramic particles but also expands the potential of LPBF technology for the fabrication of materials for extreme environments.