Abstract
The CoSn3 phase was formed along the Sn/Co interface in the Sn/Co couples reacted at 150 to 200°C. The reaction layers grew linearly with reaction time in the early stage, and then it changed to a parabolic growth when the layer reached a critical thickness. However, at the corners of the Co substrates in the Sn/Co couples, the reaction phase was the CoSn4 phase at 180°C; cracking was observed and there were no reaction phases at 200°C. The reaction phase layer showed a unique cruciform pattern. The cruciform pattern was formed either by cracking or transformation to the CoSn4 phase at the corners where stress was most intensified. With the passage of electric current from the Co toward the Sn side, the CoSn3 phase was thicker than that without the passage of electric current. A signifi cant Peltier effect has been observed which is responsible for the different reaction layer growth.