In wear resistant sintered materials, wear property is mainly dependent on the property of the hard phase dispersoid and the state of the bonding between the matrix and the dispersoids. In order to examine the feasibility of using WC particles as a dispersoid, the behavior of WC in ferrous alloy matrix during sintering was studied.
Pure Fe powder and alloy steel powder were used as matrix material, and these powders were blended with WC and graphite powder.
With the variation of additives and sintering conditions, the dissolution phenomena of WC particles were investigated by observing microstructural change of the WC particles and the matrix. Also the distribution of alloying elements decomposed from WC dispersoids was investigated by using a X-ray microanalyser.
In Fe-WC-C system containing more than 0.8% carbon and in (Fe-Cr-Mo-V)-WC-C system containing more than 1.5%, all of the WC particles were partially dissolved and the matrix around WC particles was transformed into hard phase such as fine pearlite, bainte and martensite. In Fe-WC-C system containing less than 0.8% carbon and (Fe-Cr-Mo-V)-WC-C system containing less than 1.5%, all of the WC particles were transformed into carbide particles consist of outer layer, $\eta$ carbide, and inner layer, $W_2C$ carbide. The shape of the carbide particles were changed by dissolution of the outer layer, $\eta$ carbide. Also the matrix around the carbide particles was changed into hard phase as observed in the case of matrix with higher carbon content.
From this experimental results of the present study, it is concluded that the morphology of WC dispersoid and the state of bonding between matrix and dispersoid can be optimized by choosing proper matrix material and carbon content in the matrix so as to improve wear property of sintered material which contains WC as a dispersoid.
