Mechanical properties of Ag-Ni super-laminates produced by rolling

Multilayer materials which have the layer thickness with nano-scale or meso-scopic scale have been produced by the repeated process of diffusion bonding and rolling. We call these multilayers 'super-laminates'. The strength of Ag-Ni super-laminates increases with the decreasing layer thickness. The ultimate tensile strength reached 1000 MPa for the laminates which have a layer thickness < 10 nm. The strength of super-laminates is concerned with the layer thickness and can be estimated by Orowan type equation. The microstructures of the specimens were stable for annealing treatment at temperatures below 673 K. The softening occurred for the specimens annealed at temperatures > 673 K due to the structural change. This repeated rolling process may be expected to produce super high strength materials with ductility by introducing the proper heat treatment. (C) 1997 Elsevier Science S.A.