From barrier to dislocation source and transmitter: atomistic insights into the inverse effect of semi-coherent interfaces during nanoindentation of BCC metal bilayers
Year: 2026
Type: article
Abstract: Semi-coherent interfaces are widely recognized as effective barriers to dislocation motion and are therefore considered as a key strengthening element in metallic multilayers. However, whether this role remains unchanged under different nano-indentation loading directions is still largely unexplored. Using molecular dynamics simulations, this work demonstrates that the mechanical response of semi-coherent bcc interfaces is fundamentally governed by the indented layer. By simply reversing the indentation direction in Fe/V bilayers, the interface undergoes a remarkable transition from a dislocation barrier to an active dislocation source and transmitter. This transition is driven by the decomposition of the pre-existing <100> misfit dislocations into mobile 1/2<111> dislocations within the V substrate, while the indented Fe layer remains elastically deformed. As a result, interface-mediated plasticity induces pronounced softening when the Fe layer thickness falls below a critical value, in contrast to the strengthening observed for the V/Fe bilayer. The same deformation mechanisms are identified in Ta–W bilayers, demonstrating that the observed inverse interface effect is not material-specific but represents a general characteristic of bcc semi-coherent interfaces. These findings provide a new atomistic framework for understanding and tailoring the mechanical response of multilayered materials through interface engineering.
Institutions: University Ferhat Abbas of Setif, Ruhr University Bochum
Language: English
Subfield: Metals and Alloys
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W7204440212