Reactive wetting of low carbon steel by Al 4043 and 6061 alloys at 600-750 °C

Wetting of low carbon steel by two industrial grades Al (4063 and 6061) alloys was investigated by the modified sessile drop method at temperatures between 600 and 750 degrees C under high vacuum. The formation of intermetallics which would lead to the replacement of the oxidized surface by a clean surface, and further induces the spreading. The formation of precursor film in the wetting of Al 6061/steel was caused by subcutaneous infiltration mechanism. The different chemical compositions in Al alloys also lead to the different interfacial structures and spreading dynamics. The Mg in Al 6061 alloy reduces the oxide film and then make molten Al is easier to infiltrate into the steel substrate; the high affinity of the Si in Al 4043 alloy at Al/steel interface which induced the segregation of Si. The reduction reaction by the Mg in Al 6061 and the reaction between Al and Fe caused the apparent activation energy for spreading is almost an order of magnitude larger than Al 4043. (C) 2016 Elsevier B.V. All rights reserved.