Laser-induced graphite superhardness and transformation into amorphous carbon in a near-surface layer of cast iron

An analysis of the microstructure and Raman spectra shows that the formation of superhard structures in a near-surface layer of cast iron, observed upon a special laser treatment of the gray iron surface covered by a thin layer of inductor (copper), is related to the transformation of graphite (present in the cast iron) into amorphous carbon. A possible mechanism of this process is proposed, which includes the stages of graphite transition into a liquid phase, supercooling of the liquid carbon, and its transformation into a condensed amorphous phase.