Effects of laser beam profiles on the microstructure and magnetic properties of L-PBF soft magnetic alloys

Abstract

The growing demand for environmentally sustainable technologies has intensified research into high-frequency motors and transformers, where Fe-Si soft magnetic alloys play a crucial role due to their exceptional magnetic properties. However traditional manufacturing methods limit geometric freedom and degrade alloy performance capabilities, hindering the development of advanced applications. To overcome these issues, laser powder bed fusion (L-PBF) offers a promising route by enabling complex shapes, yet mitigating eddy current losses remains challenging at elevated frequencies. As a preliminary study, this work investigates the effect of adjusting laser beam profiles (Gaussian versus ring) on the eddy current losses and magnetic properties of Fe-Si alloys produced by L-PBF. A microstructural analysis demonstrates that the ring beam produces a broader, shallower melt pool, fostering coarser grains and a pronounced < 100 > crystallographic texture along the build direction. These microstructural features significantly reduce the coercivity and core loss of the material, strongly highlighting their effectiveness in addressing the aforementioned challenges related to the eddy current. Additionally, the ring beam increased the build rate by approximately 108%, clearly illustrating enhanced productivity without compromising quality. This study confirms that modifying the laser beam profile effectively controls eddy current losses, enhancing the magnetic performance of Fe-Si soft magnetic alloys fabricated via additive manufacturing.