Microstructure Evolution And Mechanic Properties Of Tungsten Alloy Rod By Extrusion Under High Speed Loading

As an important kind of penetrator material, tungsten-based alloy will carry the high strain rate and impact pressure when impacting the target, resulting in the alloy deformation, even failure immediately. Forming process, sintering process and aspect ratio of the samples have an important influence on the dynamic mechanical properties of the tungsten-based alloy. Focusing on the above-mentioned core question, the research on the mechanical behavior, failure mechanism and its influencing factors of93W-Ni-Fe alloy under the dynamic loading of high strain rate were studied in this paper.Yield strength of alloy in the quasi-static was tested with universal testing machine (Instron3369), the microstructure of samples compressed was analyzed by optical microscope and Scanning Electron Microscope (JSM-6360LV), respectively, the micro-hardness of tungsten grains and matrix phase was detected by Switzerland CSM Ultra Nanoindentation Tester (UNHT). The results showed that:1. The plasticity of the93W-Ni-Fe alloy was excellent at high speed loading, all the samples had never be destroyed in the whole test.2. The flow stress of93W-Ni-Fe alloy raised rapidly and yielded quickly as the strain increasing, the strain-strengthening effect was offset by the thermal softening effect, which resulted in the true stress-strain curve inclining to equilibrium.3. Tungsten grains of microwave sintered alloy were finer and distributed more uniformly in matrix phase, the deformation proportion of matrix phase was much bigger in dynamic compression, thermal softening effect was more obvious, the true strain-stress curve was more gentle, which improved adiabatic shearing sensitivity of the alloy; there were obvious adiabatic shear bands on the radial section of the forward extruded, otherwise screw extruded microwave sintered samples was45°to the impact direction when the impact pressure was8atm.4. The deformation area of adiabatic shearing appeared in the screw extruded alloy when the impact pressure was6atm, which became much more obvious when the impact pressure was increased to8atm and the deformation of tungsten grains was more intense at the same time. Screw extruded tungsten-based alloy had better adiabatic shearing sensitivity.