Preparation of spherical WMoNbTa refractory high entropy alloy powder by radio frequency plasma and its laser powder bed fusion densification

作者：Qi Shi, Yumin Zhao, Feng Qin, Feng Qin, Chong Tan, Huanwen Xie, Yuyuan Zhao, Xin Liu, Ge Zhou · 发表于：Journal of Materials Research and Technology · 年份：2025 · DOI：10.1016/j.jmrt.2025.08.017 · 被引用次数：5 · 研究领域：High Entropy Alloys Studies、High-Temperature Coating Behaviors、Intermetallics and Advanced Alloy Properties

The fabrication of refractory high-entropy alloys (RHEAs) with balanced mechanical properties remains challenging due to inherent brittleness and defect sensitivity during additive manufacturing. In this work, high-quality spherical WMoNbTa RHEA powder was synthesized through an innovative spray granulation (SG) and radio frequency plasma spheroidization (RFPS) hybrid approach, achieving >98% spheroidization efficiency and low impurity levels (O: 850 ppm, C: 350 ppm). The optimized RFPS process enabled uniform single-phase BCC powder with enhanced flowability (8.5 s/50g) and tap density (8.33 g/cm 3 ), critical for laser powder bed fusion (LPBF) densification. Coupled with volumetric energy density (VED) optimization, macrocrack-free LPBF samples were fabricated, though micropores and grain boundary microcracks persisted due to rapid solidification stresses. Subsequent hot isostatic pressing (HIP) at 1350°C/150 MPa/4 h eliminated microdefects, suppressed oxygen segregation at grain boundaries, and promoted full recrystallization, resulting in a 17.1% increase in ultimate compressive strength (1716 MPa) and 31.1% enhancement in fracture strain (11.8%) compared to the as-built sample. This work pioneers a dual-process synergy: (1) SG-RFPS for high-purity spherical RHEA powder synthesis and (2) LPBF-HIP for defect-tolerant microstructure engineering, offering a scalable strategy to overcome the strength-ductility trade-off in RHEA additive manufacturing.