First-principles study of tensile and shear strength of an Fe2Al5//Fe interface

The interfacial strengths of a low misfit Fe2Al5//Fe interface structure found at aluminum-steel joints has been studied using density functional theory. An interface between Fe and Fe2Al5 was selected based on a criteria of low lattice misfit and number of atoms. Through virtual tensile testing of bulk Fe2Al5 and the interface structures we show that the energy-displacement curve can be well described by including extra polynomial terms in the Universal Binding Energy Relation (UBER). It is shown that the Fe2Al5//Fe interface has a higher tensile strength than the bulk Fe2Al5 phase. We also find that the shear deformation process potentially can be initiated from an Fe-terminated interface.