Observation and characterisation of the surface hardness enhancement of the laser remelted NiCrBSi coating

The hardness enhancement on the surface of the laser remelted NiCrBSi coating was observed and characterised by employing X-ray photoelectron microscopy and nanoindentation techniques. The result indicates that, under the line energy density of 80 J/mm, there is an agglomeration of the borides on the top 20 μm of the remelted coating that significantly enhanced the surface hardness as high as 1.5-fold stronger to 13 GPa than that of the main body of 8.5 GPa. Owing to the high concentration of the borides, the elemental distribution of the remelted surface has been modified significantly. In addition by varying the laser energy, the depth of the surface enhanced regions can be modified.