Detailed Evolution Mechanism of Interfacial Void Morphology in Diffusion Bonding

Similar diffusion bonding of 1Cr11Ni2W2MoV stainless steel was conducted at different bonding temperatures. The interface characteristics and mechanical properties of joints were examined, and the evolution of interfacial void morphology was analyzed in detail. The results showed that there were four typical interfacial void shapes generating sequentially: the large scraggly voids, penny-shaped voids, ellipse voids and rounded voids. The variation of interfacial void shape was dominated by surface diffusion, while the reduction of void volume was ascribed to the combined effects of plastic flow of materials around voids, interface diffusion and volume diffusion. Owing to the elimination of void from the bonding interface, the sound joint obtained could exhibit nearly full interfacial contact, and present excellent mechanical properties, in which the microhardness and shear strength of joint matched those of base material.