Fabrication of Fe-Cr-Al Oxide Dispersion Strengthened PM2000 alloy using Selective Laser Melting**

The expansion in application of the selective laser melting (SLM) process for fabrication of new alloy materials continues. However, to date, there has been no investigation of the effect of this process on the final microstructure of ‘melt sensitive’ powder alloys such as mechanically alloyed oxide dispersion strengthened (ODS) FeCrAl. In this study commercial PM2000 powder, a ferritic ODS alloy strengthened by a fine dispersion of nano-scale yttria particles, was used in a layer based SLM rapid prototyping process to manufacture thin walls. Laser input power and scan speeds were varied between 10-50W and 0.1-0.3ms, respectively. Electron channelling contrast images of the resulting microstructures revealed a columnar grain structure aligned perpendicular to the surface of the build substrate. Measurements of the diameter of yttria particles retained in the walls using transmission electron microscopy indicated that agglomeration and coarsening had taken place for samples processed at the slowest scan speed. By contrast ODS particles retained in a wall made at twice the slowest scan speed showed no evidence of agglomeration and appeared to have coarsened to a lesser extent, exhibiting a smaller mean diameter. This opens the possibility of using these alloys in novel applications processed using rapid prototyping technologies.