Preparation and characterization of melt-spun nickel-based alloys containing heavy metals

Abstract

The solidification behaviour and morphology of some nickel-based hardfacing alloys containing heavy metals such as tungsten have been studied by scanning electron microscopy and transmission electron microscopy. These alloys are very sensitive to different cooling rates (from as cast to melt spinning). At low cooling rates, these alloys present as primary phases, i.e. the stable carbide M 7C 3 or the double carbide M 6C (η type), according to the silicon content. For high cooling rates, the alloys occur as either amorphous (high silicon content) or microcrystallized structures depending on silicon level. In this latter case, the solid solution Ni(α) and the metastable carbide M 23C 6 are observed.