Solidification Microstructure of In-situ Fe-TiC Hard Coating Synthesized by Laser Surface Treatment

Laser manufacturing is currently a hot area of research. Synthesis of hard coatings on commercial substrates, such as carbon steel, was the subject of several researches in previous decades. In this study, a new method was applied for in-situ synthesis of Fe-TiC composite coating. The TiC particles were produced by laser surface treatment of a precursor of ilmenite and graphite powders. The powder blend was mechanically activated to make the laser reduction of ilmenite possible. Variations of solidification conditions resulted in formation of a series of microstructures, from the substrate to surface. Gradients of size, morphology and distribution of particles were observed. Moreover, by progress of solidification front various microstructures were developed in the matrix, including planar, cellular, dendritic and eutectic growths. Some new microstructural aspects were also detected. Microhardness measurements verified that the formation of a graded microstructure resulted in appropriate properties

Keywords:

Laser Additive Manufacturing , Functionally Graded Material , Hard Coating , Fe-TiC Composite , In-situ Synthesis