Structure and properties of the Fe3Al-type intermetallic alloy fabricated by laser engineered net shaping (LENS)

The microstructure and mechanical properties of the Fe3Al-0.35Zr-0.1B alloy fabricated by the Laser Engineered Net Shaping (LENS) technique are presented. Proper technological parameters of the LENS manufacturing process were selected to obtain elements with a minimal porosity and a satisfactory shape congruency. The Fe3Al based alloy samples fabricated by the LENS technique are characterized by a homogenous chemical composition and diversified grain morphology with columnar grains at the bottom and equiaxed grains at the center and edge in the analyzed sample. Phase analysis showed the presence of B2 ordered Fe3Al intermetallic and (Fe, Al)2Zr Laves phases. An isothermal annealing carried out at 450 °C for 50 h led to a phase transformation from a B2 to an equilibrium D03 phase. The Fe3Al based alloy samples with the B2 structure, directly after the LENS process and with the D03 structure after annealing, exhibited similar yield strength and ultimate tensile strength. However, the presence of the D03 structure caused a noticeable increase of elongation, especially at elevated temperatures.