Mechanical properties of laser-deposited composite boride coating using nanoindentation

Nanoindentation proves to be an effective technique to measure mechanical p roperties of "composite" materials, as it has high spatial resolution that enables estimation of properties even from fine grains, particles, and prec ipitates. The elastic modulus, E, of the composite boride coating deposited on AISI 1010 steel using the laser surface engineering (LSE) process has b een computed using the nanoindentation technique. The highest E value of 47 7.3 GPa was achieved for coating in a sample that contained 0.69 volume fra ction of TiB2 particles in the coating after processing with the highest la ser traverse speed of 33 mm/s. A comparison between the theoretical and exp erimental computation of the elastic modulus suggests that theoretical elas tic modulus values are lower than computed elastic modulus, as the latter i ncludes the effect of dissolution of fine TiB2 particles in Fe matrix and m etastable phase formation such as FeaBb and TimBn. Dissolution of fine TiB2 particles in the Fe matrix in the coating region has been corroborated by transmission electron microscope (TEM) micrographs and corresponding energy -dispersive spectroscope (EDS) analysis and selected area diffraction (SAD) pattern.