Soft-Magnetic Behavior of Fe-Based Nanocrystalline Alloys Produced Using Laser Powder Bed Fusion

Abstract

Herein, an extensive experimental study is presented on the influence of the major process parameters of the laser powder bed fusion (LPBF) technique on the bulk density and soft-magnetic properties of Fe-based bulk metallic glasses (BMGs). For this purpose, 81 samples are manufactured using the combinations of different process parameters, that is, layer thickness (t: 50–70 μm), laser power (P: 70–130 W), laser scan speed (v: 900–1100 mm s−1), and hatch spacing (h: 20–40 μm). High bulk density (≥99%) is achieved utilizing low P and v combined with low h and t in order to decrease energy input to the powder, preventing cracks associated with the brittle nature of BMGs. Furthermore, it is indicated that h = 30 μm and v = 1000 mm s−1 play a determining role in acquiring high saturation magnetization (≥200 Am2 kg−1). Due to the laser scanning nature of the process, two distinct microstructures evolve, melt-pool (MP) and heat-affected zone (HAZ). According to thermal modeling performed in this study, laser power has the major effect on the thermal development in the microstructure (thermal gradient evolved between the two hatches and the cooling rate from MP through HAZ).