H.N. Cai

Strength-improved Zr-based metallic glass/porous tungsten phase composite by hydrostatic extrusion

Hydrostatic extrusion, as a quite rarely applied technique, is used for the deformation of the Zr-based metallic glass/porous tungsten phase composite prepared by pressure infiltration. The fracture strength increases from 1852 MPa for the as-cast composite to 2112 MPa for the as-extruded composite. An apparent work hardening behavior was also observed in the as-extruded composite. The improved mechanical properties of the as-extruded composite are proposed to contribute to the stable interface between the metallic glass phase and the tungsten phase and the high dislocation density of the tungsten phase. (c) 2007 American Institute of Physics.

Microstructure and properties of atmospheric pressure chemical vapor deposition of tungsten carbide

Tungsten carbide / tungsten coating is prepared from tungsten hexafluoride (WF6), hydrogen (H2) and dimethyl ether (DME) mixtures by chemical vapor deposition (CVD) under atmospheric pressure conditions. The cross-sectional structure and the surface morphology of the coating were observed using optical microscope and scanning electron microscopy. It is found that the tungsten layer is columnar and tungsten carbide / tungsten coating is fine grain lamellar structure. The preferential growth of tungsten was proposed to be effect of DME, and the {100} preferred orientation gradually disappeared by XRD. That the pre-deposition of tungsten on the substrate can improve the coverage of the tungsten carbide coating was observed. Finally, the cross section of the micrograph was measured at 28.77 GPa with a nano-indentation.