Diffusion bonding: development of theoretical model

AbstractIn previous work, a theoretical model for solid state diffusion bonding was described. Possible diffusion bonding mechanisms were identified and mass transport rate equations for each proposed in terms of both process variables (time, temperature, pressure) and material properties. However, the mechanism of mass transfer in the vapour phase was not described since, for many diffusion bonding applications, the contribution from this mechanism will not be significant. For completeness, the vapour phase mass transport rate equations now are derived. In addition, a revised model is presented for the power law creep mechanism, based on considerations of the elastic and plastic deformation of a long triangular ridge. This new approach eliminates the assumptions, implicit in the earlier work, which break down in the later stages of diffusion bonding when the interface is substantially bonded; better agreement with experimental data also is obtained.