Interface-mediated plasticity of nanoscale Al–Al2Cu eutectics

Abstract

Laser surface re-melted Al–Al2Cu eutectic alloy with α-Al and θ-Al2Cu nanoscale lamellae exhibits high strength and good plasticity at room temperature, implying that the nanoscale θ-Al2Cu lamellae plastically co-deform with α-Al. Microscopy characterization reveal that plastic deformation of θ-Al2Cu lamellae is accommodated by localized shear on unusual slip planes of {121}Al2Cu. Herein, we elucidate interface-mediated deformation mechanisms of nanoscale Al–Al2Cu eutectics and investigate the structure and properties of the {001}Al‖{001}Al2Cu interface using atomistic simulations. Simulation results reveal that the interface is composed of two sets of misfit dislocations with the displacement shift complete vectors as Burgers vectors. We then conduct simple shear simulations to explore shear response and corresponding mechanisms of the Al–Al2Cu interface, and reveal that interfacial shear is accomplished through the gliding of misfit dislocations on the interface. Plasticity of nanoscale θ-Al2Cu lamellae is examined to be associated with localized shears on {121}Al2Cu planes, which are ascribed to the continuity of slip systems across Al–Al2Cu interfaces and accumulated lattice dislocations at interfaces.