A model for dislocation behavior during deformation of Al/Al3Sc (fcc/L12) metallic multilayers Original Research Article

In previously published work, we have reported on the microstructure and indentation hardness of nanoscale Al/Al3Sc multilayers. In this paper, the large increases in hardness that were observed with decreasing aluminum layer thickness are analyzed in detail and several simple dislocation mechanisms are proposed to describe the behavior. Strengthening can be explained by assuming that yielding occurs first by forming dislocation loops in the aluminum layers—the dislocations are constrained by layers of Al3Sc. We show that the anti-phase boundary (APB) energy of the L12 Al3Sc structure can be used to quantify the resistance of the interfaces in the multilayer structure to dislocation motion and that the thickness of the Al3Sc layer also plays an important role in determining the strengthening response.