A CuZnMnNiSi alloy interlayer reinforced W alloy/304 stainless steel composite with excellent interfacial strength

Diffusion bonding was successfully applied to join 90 W-7Ni-3Cu (W alloy) with 304 stainless steel (304SS) using CuZnMnNiSi high-entropy alloy (HEA) foil as an interlayer, and the effect of bonding temperature on micro-structure and strength of joints was investigated. The present study shows that a sound W alloy/CuZnMnNiSi/ 304SS joint with sufficient mutual diffusion across the interfaces is obtained at a relatively lower bonding temperature of 900 degrees C. It is revealed by SEM and HRTEM that the interlayer elements preferentially diffuse into the base materials due to their smaller atomic radius and high activity. At the W alloy/interlayer interface, the Zn and Mn elements in the interlayer diffuse into the (Ni, Cu)ss phase to form (Ni, Cu, Zn, Mn)ss solid solution, while the W phase/interlayer phase forms a semi-coherent bonding. At the interlayer/304SS interface, the Cu and Zn elements in the interlayer diffuse into the 304SS to produce a & gamma;-(Fe, Cu, Zn)ss supersaturated solid solution layer, while the interlayer phase/& gamma;-Fe phase also generate a semi-coherent bonding. In addition, Cu0.64Zn0.36 particles which are judged to be precipitated form the & gamma;-(Fe, Cu, Zn)ss supersaturated solid solution during the cooling process are discovered in the diffusion layer. The joint bonded at 900 degrees C shows an excellent tensile strength of 403 MPa with good ductility. The tensile fracture occurs at the interface of 304SS/interlayer, showing a mixed fracture mode of intergranular fracture and plastic fracture.

Automated summary

Diffusion bonding was used to join 90 W-7Ni-3Cu alloy with 304 stainless steel using CuZnMnNiSi high-entropy alloy as an interlayer. The study found that a strong joint with mutual diffusion across the interfaces can be achieved at a bonding temperature of 900 degrees C. SEM and HRTEM analysis revealed the preferential diffusion of interlayer elements into the base materials due to their smaller atomic radius and high activity. The joint exhibited excellent tensile strength of 403 MPa and good ductility, with the tensile fracture occurring at the interface of 304SS/interlayer.