In-situ spectroscopic analysis of laser induced plasma for monitoring of composition during direct metal deposition process

Real time chromium and iron elemental analysis during a laser direct metal deposition process was carried out using optical emission spectroscopy. Mixtures of pure chromium powder and iron powder with different weight ratios were deposited onto a substrate by delivering the powder mixtures co-axially with a high power CO₂ laser. Laser beam, powder, and substrate interaction zone was locally shielded by argon and helium inert gas to protect the process from oxidation. The laser induced plasma in both ultra violate region and visible region was monitored by a high speed spectrometer. Composition ratios of chromium and iron in the deposited structure are verified using energy dispersive X-ray spectroscopy (EDX) and are related to the spectral line intensity ratios of the two elements. The calibration curve shows a linear relationship between the composition ratios and the line intensity ratios.