Laser Powder Bed Fusion Processing of Aluminum Powders Containing Iron and Nickel

Abstract

The variety of aluminum alloys currently used in laser powder bed fusion additive manufacturing (PBF-AM) is limited, yet the demand for such materials is growing. The AM community is particularly keen on aluminum alloys that offer enhanced thermal stability. Traditionally, this trait has been instilled through transition metal additions that form stable aluminides. This project seeks to devise new PBF-AM materials in this context starting with a precursory study into the effects of iron and nickel additions. Here, gas atomized Al-1Fe and Al-1Ni (wt.%) powders were processed via PBF-AM over a range of volumetric energy densities achieved through systematic adjustments to laser power, scan speed, and hatch spacing. The microstructure (OM, SEM, EDS, XRD) and physical properties (hardness, density, surface roughness) of the products were characterized. Results indicated that Al-1Fe was more responsive to processing as it densified to 99.0% of full theoretical and had a hardness of 95 HRH. Conversely, Al-1Ni only reached 97.8% theoretical density and a peak hardness of 78 HRH. It was also more prone to solidification cracking. Energy density values of at least 32.5 J mm-3 were necessary to achieve peak density and hardness.