Modeling of bonding pressure based on the plastic deformation mechanism of interfacial voids closure in solid-state diffusion bonding

The model of the diffusion bonding pressure was established using the analysis calculation method and further verified by the finite element analysis (FEA) and the experiments. The normalized temperature was defined as the ratio of temperature and the melting point of the base materials. And the normalized bonding pressure was defined as the ratio of the applied bonding pressure and the yield strength at the bonding temperature. The contribution of the plastic deformation to the void closure expressed a linear relationship with the normalized bonding pressure, of which the slope was $\sqrt{3}$. The relationship was appropriate in TiAl6V4, pure copper C11000, aluminium alloy AA6061, stainless steel SUS 304, and Ni-based alloy Inconel 617 using analysis calculation. The diffusion bonding pressure design range can be summarized as σ_n = 0.05–0.577. Subsequently, the analytic computational model was verified by FEA. The results showed that the maximum stress was concentrated in the position of the void neck. And the linear relationship between the normalized bonding pressure and the bonded ratio was also tenable. There was a stable static error existed between FEA and the analytic computational analysis. Furthermore, the experimental verification showed the verification and accuracy of the analytic computational analysis results.