Mechanisms of Wetting in Reactive Metal/Oxide Systems

Abstract

AbstractIt is shown that for metal/oxide systems with weak or moderate reactivity, wetting depends mainly on parameters related with the detailed chemistry and structure of interfacial reaction products rather than on parameters related with the intensity of interfacial reactions. Consequently, wetting can be promoted by alloying a metal matrix M with a reactive solute B capable of modifying in a favourable sense the metal/oxide interface. This can be achieved via two mechanisms depending on the value of the Wagner's interaction parameter εBo. When εBo<0 (moderate interactions between solute B and dissolved oxygen), the solute B can modify the liquid-side of the interface by adsorption, an effect that can be strongly enhanced by oxygen coming from dissolution of the oxide substrate. When εBo<<0 (strong O-B interactions in M), the solute B can lead to the formation, at the solid-side of the interface, of a new phase. When this new phase features metallic bonding wetting can be strongly improved.