Pulsed-laser atom probe studies of a precipitation hardened maraging TRIP steel

A precipitation hardened maraging TRIP steel was analyzed using a pulsed laser atom probe. The laser pulse energy was varied from 0.3 to 1.9 nJ to study its effect on the measured chemical compositions and spatial resolution. Compositional analyses using proximity histograms did not show any significant variations in the average matrix and precipitate compositions. The only remarkable change in the atom probe data was a decrease in the ++/+ charge state ratios of the elements. The values of the evaporation field used for the reconstructions exhibit a linear dependence on the laser pulse energy. The adjustment of the evaporation fields used in the reconstructions for different laser pulse energies was based on the correlation of the obtained cluster shapes to the TEM observations. No influence of laser pulse energy on chemical composition of the precipitates and on the chemical sharpness of their interfaces was detected.

Research highlights
► Changing the laser pulse energy in pulsed-laser atom probe could induce some changes in the analysis results of complex steels.
► Decreases in the evaporation fields and the ++/+ charge state ratios were detected with raising laser energy.
► Chemical composition of the intermetallic precipitates and the interface sharpness were not influenced by changing the laser energy.