Diffusion Bonding of Zr-2.5Nb Zirconium Alloy and 304L Stainless Steel with Nb/Ni Hybrid Interlayer

Diffusion bonding of Zr-2.5Nb zirconium alloy and 304L stainless steel with Nb and Ni hybrid interlayer was performed at 850-1050 degrees C under 4 MPa for 30 min. From 304L side to Zr-2.5Nb side, the typical interfacial structure of the 304L/Ni/Nb/Zr-2.5Nb joints was. (Ni, Cr, Fe) solid solution/Ni/Ni3Nb IMCs/Nb/(Zr, Nb) solid solution. Of the five layers, the nano-hardness of Ni3Nb IMCs layer was the highest, reaching ~9.22 GPa for the joint bonded at 1000 degrees C. With the increase of bonding temperature, the shear strength of the joint increased first and then decreased, and the maximum strength of 84.4 MPa was obtained at 1000 degrees C. For the joint bonded at 1000 degrees C, the fracture location was between the residual Ni layer and Ni3Nb IMCs layer, and the fracture type was a mixture of brittle fracture and ductile fracture.