Laser metal deposition and selective laser melting of Fe-28 at.% Al

The iron aluminide Fe3Al has been successfully processed by selective laser melting (SLM) and laser metal deposition (LMD). Process parameters have been determined by which defect free and dense (>99.5%) samples were produced. However, due to the low thermal conductivity of Fe3Al, preheating the substrate to 200 °C was necessary to prevent cracking during cooling. Microstructural characterization by electron backscatter diffraction (EBSD) showed that in spite of the high cooling rates large elongated grains grew in the building direction, more distinctive for SLM than for LMD. These grains show a continuous change in the crystallographic orientation. Evaluation of the compressive flow stress showed that the anisotropic microstructure results in anisotropic mechanical properties, depending whether the samples are loaded in building direction or perpendicular to it. The alloy shows a very high strength up to 600 °C and - concerning the coarse microstructure - becomes d uctile already at low temperatures.