Cai Hongnian

Effect of the β Phase on Compressive Mechanical Property of CVD Tungsten

Abstract The high pure W (HPW) was deposited on the surface of purity Cu tubes through WF 6 reduction by H 2 adopting cold-wall atmospheric pressure CVD system. Results show that the compressive strength of the tungsten tube with the mixture phase deposited at 440 °C is much lower than that with only α phase deposited at 540 °C. The existence of β phase has a significant negative influence on the compressive property. After annealing treatment at 400 °C for 1 h, the β phase in the mixture will disappear, and its compressive strength reaches the level of the as-deposited α -W.

Adiabatic Shear Localization and Microcracks Initiation in an Extruded Tungsten Heavy Alloy

Abstract The influence of extrusion deformation ratio on the dynamic mechanical behavior in a tungsten heavy alloy was investigated under uniaxial compression with loading direction perpendicular to the fiber orientation. With extrusion deformation ratio increasing from 0 to 40.8%, the sensitivity of adiabatic shear banding shows an obviously rising tendency. Microcracks could be seen near the centre of the shear band and initiate at the interface of tungsten-matrix as well as the interior of tungsten. Moreover, the observation by the transmission electron microscopy reveals the dislocation pile-ups at the interface of tungsten-matrix and the presence of a microcrack propagating along the boundary and inside of the subgrain in the interior of tungsten within the shear band.

Multiscale Numerical Simulation of the Shaped Charge Jet Generated from Tungsten-Copper Powder Liner

Formation process of the shaped charge jet of W-Cu powder liner was simulated with smoothed particle hydrodynamics (SPH) method of LS-DYNA software. With the digital image process technique and macro-micro coupling method, a multiscale finite element model was established, and the high speed deformation process of the microstructure driven by explosive detonation in the liner of shaped charge was successfully simulated. The Cu phases were susceptible to serious deformation while the tungsten phase has less deformation. Besides, the temperature field of the microstructure during the shaped charge deforming was calculated, and a discussion of the deformation mechanism of the liner was given. The methods proposed in this paper would be of help in microstructure design of shaped charge materials.