Dissolution process of surface oxide film during diffusion bonding of metals

• DOI: 10.1007/bf00543942
• Publication Date: 2004-11-22T15:24:40Z
• Authors: Y. Takahashi; T. Nakamura; K. Nishiguchi
• Keywords: 0203 mechanical engineering; 02 engineering and technology

Two models of the dissolution process of surface oxide film in metals (copper and titanium) are described in order to estimate the dissolution time t s required for the oxide film to dissolve in the metals completely. One is based on impurity diffusion (model 1). The other is given by reaction diffusion (model 2). Model 1 was applied to estimate t s in copper and α-titanium but model 2 for t s of β-titanium because of the formation of α-phase. In these models, the dissolution process is assumed to be controlled by the oxygen diffusion in metals. Bonding tests were performed in order to verify the calculated results. The experimental results suggest that model 1 is valid in Cu-Cu bonding. Also, as for β-titanium, no retardation of the bonding process was observed. This was in agreement with model 2. However, for α-titanium below 1000 K, the retardation time was much longer than the dissolution time calculated by model 1, i.e. the retardation below 1000 K cannot be dictated by the diffusion-controlled process. A new model is therefore proposed. The dissociation rate of the oxide film is taken into account in the new model. This new model can explain the retardation of the bonding process.