Prediction of strong adhesion at the MoSi2/Fe interface

We report a spin-polarized periodic density functional theory investigation of the atomic structure, bonding, and ideal work of adhesion of the MoSi2/Fe interface, in order to explore the potential of MoSi2 as a protective coating for steel. We find that MoSi2 strongly adheres to Fe, with an ideal work of adhesion of ~ 3.85 J/m2 for two low-index, low-strain interfaces. This value will be a lower bound to measured adhesion energies, since the latter will be larger due to plasticity. This ideal adhesion energy for a ceramic coating to Fe is much stronger than predicted previously for ceramic coating materials such as ZrC and TiC. We attribute this stronger adhesion to increased covalent interfacial bonding for MoSi2/Fe compared to metal carbide/Fe interfaces (where metallic bonding plays a larger role), as evidenced by the rearrangement of electron density and the character of the local density of states upon formation of the interface.