Mechanical property and numerical simulation on W-Ni-Fe alloys

Tungsten alloy is a type of particulate reinforced composites and has wide military and civilian applications. It can be used as kinetic energy penetrator, radiation shielding material, balance mass in aerospace, vibrating material in cell phones, etc. These alloys are characterized by the high strength, high density and high toughness resulting from their special microstructural features. Because of their good strength as well as ductility, these alloys have been extensively studied for a variety of promising applications. So far, most studies mainly focused on the understanding of their densification mechanism, the two-phase microstructure evolution mechanism during sintering, and the relationship between the microstructure and mechanical properties. The two-phase composite structure of tungsten alloy determines that the macroscopic deformation and fracture behavior have close relation with the microstructure of the composites. Therefore, it is important to investigate the relationship between the microstructure and the mechanical properties of the composites under different loadings, which provides practical values for the improvement of the mechanical properties and the optimization of tungsten alloys. In the current paper, MTS and SHPB techniques are used to investigate the mechanical properties of 91wt.% tungsten alloys. Based on the experimental results, finite element models of unit cells with typical structures of tungsten alloys are established. Fixed point iteration method is adopted to provide real displacement conditions for the finite element models. The effects of the microstructure parameters, such as particle size and volume fraction, on the mechanical characteristics of tungsten alloys under different tensile loadings, are examined and the corresponding stress-strain relations are obtained. The comparison of numerical predictions and the experimental results shows a good agreement. The numerical simulations demonstrate that tungsten alloys are rate-independent materials. The aspect ratios of tungsten particle have no obvious influence on the mechanical behavior of tungsten alloys, and the yield stress increase with the mass fraction of tungsten particles.