Constitutive modeling of mechanical behaviors in gradient nanostructured alloys with hierarchical dual-phased microstructures

Recent experimental studies have proved that by interface design and microstructural control of metals with the heterogeneous dual/multi-phases, one can significantly improve their mechanical properties such as fatigue resistance, strength, and plasticity. In this work, a mechanism and microstructure-based theoretical model is developed to describe the constitutive and failure behaviors of hierarchical dual-phased gradient Cu–Zr alloys. In the framework of micromechanical model, the constitutive relations of crystalline and amorphous phases are employed, and the contributions of gradient structure, dual-phase structure, back stress, and microcracks are taken into account. The theoretical results demonstrated that the proposed model can describe the constitutive behavior and mechanical properties of hierarchical dual-phased gradient Cu–Zr alloys very well, and that the simulations agree well with the experimental data. The present model is further applied to predict the mechanical properties of Cu–Zr alloys with various distributions of the grain sizes and volume fractions of microstructures. The findings of this work could be helpful to provide the theoretical basis for achieving synergy of high strength and high ductility in metallic materials by controlling the gradient distribution and dual-phases microstructures.