In situ phase engineering during additive manufacturing enables high-performance soft-magnetic medium-entropy alloys

Area of Science:

• Materials Science
• Additive Manufacturing
• Magnetism

Background:

• Additive manufacturing (AM) offers potential for soft-magnetic multicomponent alloys in electric motors and electromobility.
• Achieving high saturation magnetic flux density (Bs) and low coercivity (Hc) simultaneously in AM soft-magnetic materials is a significant challenge.

Purpose of the Study:

• To develop an AM soft-magnetic material with enhanced magnetic properties.
• To investigate the role of nano-oxides in controlling the microstructure and magnetic performance of additively manufactured alloys.

Main Methods:

• Integration of an elemental powder mixture (Fe45Co30Ni25 with Fe2O3 nano-oxides).
• Laser powder bed fusion (LPBF) processing followed by high-temperature annealing.
• In situ Lorentz transmission electron microscopy (TEM) for microstructural analysis.

Main Results:

• Formation of a single FCC-structured Fe45Co30Ni25 MEA/FeO composite with FeO nanoparticles acting as nucleation sites.
• Achieved a high saturation magnetic flux density (Bs) of 2.05 T and a low coercivity (Hc) of 115 A m⁻¹.
• Demonstrated reduced pinning effect of grain boundaries on domain wall movement in the FCC phase compared to BCC/FCC dual phase materials.

Conclusions:

• The developed LPBF MEA/FeO composite exhibits superior soft-magnetic properties compared to other AM alloys.
• The FCC structure and FeO nanoparticles are crucial for achieving low coercivity and high performance.
• This approach advances the potential of AM for high-performance soft-magnetic materials in sustainable energy applications.