Ultrafine eutectic coatings from Fe-Nb-B powder using laser cladding

Abstract In this paper, a laser cladding process was proposed to obtain ultrafine eutectic Fe-Nb-B alloy coatings on AISI 1020 steel substrate in which the power and scanning speed were defined. The laser cladding process can be used as a rapid solidification processing route to produce single laser tracks and coatings (overlapped tracks) with pre-placed powders deposited onto a mild steel substrate in order to obtain a minimal dilution between the coating/substrate. This research aims to produce a coating of Fe74.25Nb8.25B17.5 (at.%) alloy over the AISI 1020 steel substrate by laser cladding using a pre-placed powder method to investigate the parameters on coating production, dilution, microstructure, and properties. The final goal is to find an appropriate processing parameter range to obtain coatings with high hardness and possibly good wear resistance. The microstructure and behavior of powder, cladding layers and coatings were examined by X-ray Diffractometry, Differential Scanning Calorimetry, Scanning Electron Microscopy and Transmission Electron Microscopy of selected samples prepared with a Dual Beam microscope using a Focused Ion Beam. For the processing conditions used, the coatings showed larger exothermic crystallization peaks. The results of microhardness from coatings showed values of hardness over 700 HV.