Effect of Alloying Elements on Growth Behavior of Intermetallic Compounds at the Cold-Sprayed Coating/Steel Interface During Immersion in Aluminum Melt

The formation of the intermetallic compounds at the interface between cold-sprayed coatings and steel as well as interaction between coatings and aluminum melt was investigated. Coatings of AA7075 (AlZn5.5MgCu) and AA4145 (AlSi10Cu4) were deposited on the sheets of the deep drawing steel DC04. The coated samples were then immersed in the aluminum melt AlSi9Mn at the temperature of T = 610 °C for different durations in the range 30 s < t < 10 min. The reaction layer growth was examined metallographically and by means of scanning electron microscope with energy-dispersive spectroscopy. Furthermore, the intermetallic phases were identified by X-ray diffraction analysis and characterized by microhardness measurements. For both coatings, β-AlFeSi phases were shown to be the major constituent in the reaction zone. The growth kinetics of the intermetallic phases appeared to be similar for AA4145 and AA7075 coatings, while their morphology was completely different.