Effect of Micro‐Alloying Elements on the Interfacial Behavior and Properties of Diffusion‐Bonded Zirconium Alloys

Zirconium alloys are widely used as nuclear fuel cladding materials; however, achieving joints with both high strength and corrosion resistance remains challenging. In this work, diffusion bonding of Zr–Hf, Zr–Sn, and Zr–Sn–Nb alloys was systematically studied (760–840 °C, 10 MPa) to elucidate the roles of alloying elements in interfacial evolution and joint performance. Our findings show that micro‐alloying affects bonding through two coupled mechanisms: grain‐size‐dependent diffusion promotes interfacial void closure, particularly at the early bonding stage and at lower temperatures, while alloying‐element‐controlled reactions determine the type and distribution of interfacial precipitates, where Nb‐induced Zener pinning stabilizes a fine‐grained structure (~10 μm) and promotes rapid interface healing. After sufficient interfacial void closure has been achieved, alloying‐element‐controlled interfacial reactions mainly determine the type and distribution of interfacial precipitates, with Fe initiating reactions and Nb suppressing brittle Zr(Fe, Cr) ₂ while promoting Zr(Fe, Nb) ₂ formation. These mechanisms collectively determine joint properties. The Zr–Sn–Nb joint achieves the highest strength (356 MPa) but reduced corrosion resistance. In contrast, the Zr–Sn joint exhibits the best corrosion resistance while maintaining relatively high shear strength. This work provides insight into alloying–microstructure–interface relationships in zirconium alloy bonding.