Microstructure evolution process of Ferro-Aluminum based sandwich composite for electromagnetic shielding

Area of Science:

• Materials Science
• Metallurgy
• Composite Materials

Background:

• Soft magnetic composites (SWCs) are crucial for advanced electronic applications.
• Understanding the interfacial reactions in Fe-Al based SWCs is essential for optimizing performance.
• Fabrication methods like hot pressing and diffusion treatment influence composite microstructure.

Purpose of the Study:

• To propose and fabricate a novel sandwich composite (SWC) using Fe-Al soft magnetic alloy between pure iron substrates.
• To investigate the microstructure evolution and intermetallic phase formation during the fabrication process.
• To analyze the diffusion kinetics and layer growth within the composite.

Main Methods:

• Fabrication of SWC via hot pressing and diffusion treatment.
• Microstructural analysis using diffusion couple experiments at 700 °C and 900 °C.
• Characterization of intermetallic phases (FeAl2, Fe4Al13, FeAl, α-Fe(Al)) formed during diffusion annealing.

Main Results:

• The formation of FeAl2 and Fe4Al13 intermetallic phases was observed as Fe2Al5 dissolved.
• After 10 hours of diffusion treatment at 900 °C, only FeAl and α-Fe(Al) intermetallic phases remained.
• The thickness of intermetallic layers, excluding FeAl2, exhibited a parabolic relationship with diffusion annealing time, indicating diffusion-controlled growth.

Conclusions:

• The proposed SWC fabrication process leads to the formation of specific intermetallic phases.
• Diffusion annealing time significantly impacts the growth kinetics of intermetallic layers in the Fe-Al composite.
• The findings provide a basis for tailoring the microstructure and properties of Fe-Al soft magnetic composites.