INFLUENCE OF COPPER AMOUNT ON THE PACK BORONIZING BEHAVIOUR OF Fe-Cu BINARY ALLOYS

Abstract

The Fe-Cu binary alloys prepared with the addition of 1, 2, 4, 8 and 16 at. % copper along with pure iron were pack boronised at 1000 degrees C' for 3 h. The microstructure, chemical composition, phase contents and microhardness of the formed boride layers were characterized by means of XRD, (Scanning Electron Microscopy-Energy Dispersive X-ray Diffraction) SEM-EDS and Vickers Microhardness measurements. The increasing amount of Cu in the Fe-Cu alloys resulted in change of boride morphology and boride crystals growing towards the substrates become thinner and longer with saw tooth morphology. Copper atoms has neither formed a CuxBy compound nor made a solid solution in Fe-B. However, copper rich precipitates were accumulated parallel to the growth direction of the boride crystals. The amount and size of these precipitates increased with the increase of Cu in Fe-Cu alloys. The boron rich FeB phase formation was favored and total boride layer thickness increased though the hardness of the boride layer decreased with the increase of Cu in the substrates.