Creep properties of refractory niobium alloy at low temperature: Powder metallurgy vs wire-arc additive manufacturing

This study examines the low-temperature, high-stress creep behavior of a niobium-based alloy, Nb–1 wt% Zr (NbZr1), produced by wire-arc additive manufacturing (WAAM), in comparison with its powder metallurgy (PM) counterpart. Creep tests conducted at 300 °C showed that deformation in both materials was largely governed by the primary creep stage. WAAM specimens failed at 150 MPa, whereas PM specimens endured up to 250 MPa, demonstrating its superior creep strength. WAAM specimens exhibited greater strain accumulation (∼3.5 % at 150 MPa) and stronger stress sensitivity. Fractographic analysis revealed that WAAM specimens fractured primarily along interdendritic regions, while PM alloy failed due to void formation at grain boundaries and triple points. To capture strain evolution during primary creep, empirical fits based on logarithmic and power-law functions were applied, with the logarithmic model providing the best fit. These findings demonstrate that WAAM-induced microstructural features degrade creep resistance relative to PM processing and offer an empirical framework for describing primary creep strain evolution in Nb Zr alloys under low-temperature, high-stress conditions. • WAAM processed Nb 1Zr alloy shows accelerated primary creep and localized damage. • Interdendritic segregation and ZrO₂ particles govern creep strain and fracture behavior. • Empirical models capture stress assisted dislocation glide during early-stage creep.