Stability of Y-Ti-O nanoparticles during laser melting of advanced oxide dispersion-strengthened steel powder

The microstructural stability of Y-Ti-O nanoparticles during spot laser beam melting of oxide dispersion-strengthened steel powder is investigated. After the spot laser beam melting, Y2Ti2O7 oxide nanoparticles are successfully retained without dissolution or transformation. However, their particle size is considerably coarser than typical Y2Ti2O7 nanoparticles due to the active agglomeration of the Y-Ti-O nanoparticles, Cr-carbides, and Ar bubbles. In particular, an unexpectedly large volume of Ar bubbles embedded or attached to the Y2Ti2O7 nanoparticles is observed. The Ar gas bubbles seem to accelerate the particle agglomeration. No other phase is observed than Y2Ti2O7 oxide, Cr-carbide and Ar bubble in the sample. (C) 2015 Elsevier B.V. All rights reserved.