A CONSTITUTIVE MODEL OF NANOCRYSTALLINE BIMODAL Ni-W ALLOYS

This paper presents a new composite constitutive model to quantitatively describe the constitutive behavior and its influencing factors of nanocrystalline bimodal Ni-W alloys. The simulation results show that the calculated results of the constitutive model are in good agreement with the experimental data and can be used to describe the mechanical behavior of Ni-W alloys. Based on this model, the stress-strain curve of the material is calculated, and the influences of coarse grain size and strain rate on the mechanical behavior of nanocrystalline bimodal Ni-W alloy are studied. The results show that increasing the coarse grain size will reduce the strength of the material and improve its toughness. It is further proved that the ultrafine grain region of bimodal materials mainly provides high strength, while the coarse grain region mainly provides high toughness. At the same time, although increasing the strain rate can improve the strength and hardness of the material, this strengthening effect cannot be used to improve the material properties.