Etude des propriétés mécaniques et structurales d'alliages de types Fe-W-C- élaborés par la métallurgie des poudres

Abstract

In order to characterize Fe-W-C alloys fabricated by powder metallurgy process, different experimental techniques including: X ray diffraction, optical microscopy, differential thermal analysis, micro-hardness and wear tests were used. The results obtained, show that the microstructure of the sintered samples principally depends on their chemical composition. It is mainly composed of (c.c) solid solutions in the case of agglomerate contents equal to 5 wt % W and carbon additions lower than 1 wt%. When contents of W and C are increased, microstructure of compacts became bainitic with a more or less homogeneous M6C carbides. The micrographie examination revealed the presence of a residual porosity; essentially consisting in secondary pores characterized by irregular shapes and important sizes. Furthermore hardness and wear tests carried out on different samples permitted to point up the influence of different parameters (microstructure, grain size, relative density, residual porosity...) on the properties of the sintered samples. In particular, highest values of microhardness and wear resistance have been obtained in the case of Fe-20w-l .5%C samples.