Modeling the effects of interface spacing on the mechanical properties of heterogeneous laminates

In this study, a constitutive model accounting for the evolution of statistically stored and geometrically necessary dislocation (GND) densities is developed to reveal the mechanism responsible for the enhanced strength of Cu-bronze heterogeneous laminates with decreasing interface spacing when the interface spacing is smaller than twice the width of the interface affected zone (IAZ). GND density first increases with decreasing interface spacing above twice the IAZ width, then decreases significantly with a further reduction in interface spacing below twice the IAZ width where IAZs associated with adjacent interfaces overlap with each other, leading to improved tensile ductility with decreasing interface spacing above twice the IAZ width and diminished ductility below. In contrast, GND density gradient within the IAZ increases consistently with decreasing interface spacing, leading to higher back stresses which contribute to higher flow stresses that are responsible for the further enhanced strength when the interface spacing is smaller than twice the IAZ width. This work highlights the importance of interface spacing on the mechanical properties of heterogeneous laminates.