Role of gradient heterogeneous interfaces in synergetic strengthening and toughening of layered CuCrZr/Cu composites

Layered CuCrZr/Cu composites with different densities of gradient heterogeneous interfaces were designed and prepared by powder metallurgy combined with rolling and aging. The prepared layered CuCrZr/Cu composites achieved better comprehensive properties than the homogeneous CuCrZr alloy. The evolution of local strain was analyzed by high resolution digital image correlation (DIC). A strain-transfer from CuCrZr layer to adjacent Cu layers appears at the gradient heterogeneous interface, which relieves the strain localization of CuCrZr layers in layered CuCrZr/Cu composites. The incompatible deformation between the gradient heterogeneous microstructures across the layer interface leads to the generation and accumulation of geometrically necessary dislocations (GNDs), which results in extra work hardening and hetero-deformation induced (HDI) strengthening. The increase in the density of gradient heterogeneous interfaces can enhance the interface constraint behavior and produce a greater HDI strengthening effect, which tends to improve the work hardening ability and HDI stress of layered CuCrZr/Cu composites. Furthermore, various crack propagation modes of crack deflection, multiple cracks and crack blunting caused by uneven stress/strain partition at the gradient heterogeneous interface of layered CuCrZr/Cu composites were characterized by in-situ tensile tests.