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Abstract: The two-phase metallic composites, composed by the metallic particulate reinforcing phase and the metallic matrix phase, have attracted a lot of attention in recent years for their excellent material properties. However, the constitutive modeling of two-phase metallic composites is still lacking currently. Most used models for them are basically oriented for single-phase homogeneous metallic materials, and have not considered the microstructural evolution of the components in the composite. This paper develops a new constitutive model for two-phase metallic composites based on the thermally activated dislocation motion mechanism and the volume fraction evolution. By establishing the relation between microscopic volume fraction and macroscopic state variables (strain, strain rate and temperature), the evolution law of volume fraction during the plastic deformation in two-phase composites is proposed for the first time and introduced into the new model. Then the new model is applied to a typical two-phase tungsten-based composite – 93W–4.9Ni–2.1Fe tungsten heavy alloy. It has been found that our model can effectively describe the plastic deformation behaviors of the tungsten-based composite, because of the introduction of volume fraction evolution and the connecting of macroscopic state variables and micromechanical characteristics in the constitutive model. The model's validation by experimental data indicates that our new model can provide a satisfactory prediction of flow stress for two-phase metallic composites, which is better than conventional single-phase homogeneous constitutive models including the Johnson–Cook (JC), Khan–Huang–Liang (KHL), Nemat-Nasser–Li (NNL), Zerilli–Armstrong (ZA) and Voyiadjis–Abed (VA) models. [Copyright &y& Elsevier]

Abstract: This paper develops a new constitutive model for HCP metals subjected to high strain, high strain rate and high temperature based on the theory of thermally activated dislocation motion in crystal materials. The constitutive parameters of the material are determined by a new efficient method composed of a global genetic algorithm and a local penalty-function algorithm, which guarantees that the constitutive parameters are a globally optimal solution in their theoretically allowed ranges. The application of the model to Ti6Al4V alloy shows that in the high strain rate regime, the model prediction is much more accurate than those by the Johnson–Cook and Zerilli–Armstrong models. [Copyright &y& Elsevier]