Design of Core-Shell Structured Magnetic Microwire with Desirable Properties for Multifunctional Applications

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Amorphous Co-rich microwires exhibit promising soft magnetic and mechanical properties for sensors and composites.
• Residual stress from manufacturing degrades microwire performance.
• Conventional annealing methods often compromise mechanical integrity when improving magnetic softness.

Purpose of the Study:

• To develop an annealing technique that enhances both magnetic and mechanical properties of amorphous microwires.
• To investigate the formation of a nanocrystal-core/amorphous-shell structure.
• To establish the relationship between microstructure and properties in the novel composite structure.

Main Methods:

• Utilized a multi-step direct current annealing (MSDA) technique on as-quenched amorphous Co68.15Fe4.35Si12.25B13.25Zr2 microwires.
• Varied current intensity during annealing to control nanocrystal formation within the core.
• Analyzed the resulting core/shell microstructure and its impact on magnetic and mechanical characteristics.

Main Results:

• Successfully created a unique nanocrystal-core/amorphous-shell composite structure.
• Optimized nanocrystal density and size by adjusting annealing current intensity.
• Achieved significant improvements in soft magnetic properties and giant magneto-impedance (GMI).
• Preserved the excellent mechanical strength of the amorphous shell.

Conclusions:

• MSDA is an effective method for fabricating core/shell structures in amorphous magnetic microwires.
• The optimized nanocrystal-core/amorphous-shell structure offers superior soft magnetic and GMI performance.
• This approach provides a new pathway for developing advanced magnetic materials with tailored properties.