Molecular dynamics and first-principles calculations on the wetting behavior and mechanism of molten Al on nickel-infiltrated steel: A cross-scale simulation

Abstract

Wetting behavior and mechanism of melting Al on Ni-infiltrated steel were investigated using the cross-scale simulations. The molecular dynamics calculations were employed firstly to intuitively exhibit the influence of amount of nickel infiltration (on the surface of steel substrate) on wettability of Al droplet. The micro-mechanisms affecting wettability, such as the bonding characteristic and charge distribution on wetting interface, were researched using the first-principles calculations. The results indicate that, the chemical reactions occur on Al droplets/Ni-infiltrated steels wetting interfaces. With the increasing amount of Ni infiltration, the main interfacial intermetallic compound (IMC) transforms from Fe2Al5 to NiAl and finally to Ni3Al. Although the atomic bonds on Al/Fe2Al5, Al/NiAl, and Al/Ni3Al interfaces all show both ionic and covalent characteristic, the work of adhesion for the three Al/IMC interfaces follows the order of Al/Fe2Al5 > Al/NiAl > Al/Ni3Al. This phenomenon indicates that the interfacial bonding strength between Al droplet and the generated IMC decreases gradually with the increasing amount of Ni infiltration, and leading to the improving wettability because the wettability is negatively correlated with the Al/IMC bonding strength on wetting interface.