AN INVESTIGATION OF MICRO-STRUCTURE OF DT TYPE STEEL-BONDED TUNGSTEN CARBIDE

The micro characteristics of DT alloy have been given by composition analysis, mophology and structural features of various phases and by the influence of heat treatment process, therefore, the improvement of its properties has been theoretically discussed. Mutual solution and diffution carry on between tungsten carbide phase and matrix phase when the alloy is heated at high temperature. The distribution of various elements is in accord with certain rules. The result of mutual diffusion is increase of binding strength between two phases. In there are two kinds of tungsten carbide particles with different tendency of solvation, deposition and growth. They have different mophology and composition. One kind of this particles has more W diffusion into matrix and obvious tendency to form spherical particles, while the other hind of particles has less W diffusion into matrix and unobtrusive tendency to form spherical particles.It is known by comparison between them that the properties of alloys can be improved if tungsten carbide particles become spherical. Tungsten carbide phase solubilized other elements remains the oiginal structurol but the lattice parameters are less than the original WC. and lattice parameters a and c will further decrease with the increase of tempering temperature.