Structure, Microstructure, Hyperfine, Mechanical and Magnetic Behavior of Selective Laser Melted Fe_92.4Si_3.1B_4.5 Alloy

Abstract

A disordered ε-FeSi crystalline structure was produced by selective laser melting in Fe92.4Si3.1B4.5 powder alloys fabricated with different laser powers at a laser scanning speed of 0.4 m/s. The phase formation, microstructure, roughness, microhardness, and hyperfine and magnetic properties were studied using X-ray diffraction, scanning electron microscopy, atomic force microscopy, a profilometer, a microdurometer, transmission 57Fe Mössbauer spectrometry and vibrating sample magnetometry. The aim of this work was therefore to study the effect of laser power on the phase formation, microstructure, morphology, and mechanical, hyperfine and magnetic properties. The XRD patterns revealed the coexistence of a bcc α-Fe0.95Si0.05, a tetragonal Fe2B boride phase and a disordered ε-FeSi type structure. The existence of the disorder was confirmed by the presence of different FeSi environments observed in the Mössbauer spectra. The Fe2B boride contained about 51–54% of Fe atoms. The porosity and roughness decreased whereas laser power increased. The sample produced with a laser power of 90 W had a smooth and dense surface, high microhardness (~1843 Hv) and soft magnetic properties (saturation magnetization Ms = 200 emu/g and coercivity Hc = 79 Oe).

Keywords

• Fe-Si-B alloys
• selective laser melting
• magnetic behavior
• XRD
• mechanical properties