Wetting of molten Bi–Sn alloy on amorphous Fe78B13Si9

Wetting behavior of amorphous Fe78B13Si9 substrate by molten Bi–Sn alloy was investigated by sessile drop technique. Liquid–solid reaction and the crystallization reaction occur in the reactive zone of the liquid/solid interface. We found that the equilibrium contact angle on amorphous Fe78B13Si9 substrate does not decrease monotonically with increasing temperature. Pre-annealing of amorphous Fe78B13Si9 made the equilibrium contact angle increase with the increase of the pre-annealing temperature. We propose that the crystallization reaction in the interface provides an additional driving force for the observed spreading process. By analyzing wetting kinetics, three wetting stages were identified in the wetting process.