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

• Iron-based sandwich composite was fabricated.
• Microstructure evolution process was observed by EBSD.
• Fe2Al5 is preferable formed at 700 °C diffusion treatment.
• Only FeAl and α-Fe(Al) left after 10 h of diffusion treatment at 900 °C.

In this paper, sandwich composite (SWC) with Fe–Al soft magnetic alloy sandwiched between pure iron substrates was proposed and fabricated by hot pressing and diffusion treatment. The microstructure evolution process of the composite was investigated. Fe/Fe2Al5/Fe diffusion couple was obtained at 700 °C and subsequently kept at 900 °C for further isothermal diffusion. During the diffusion reactive process, we confirmed that major FeAl2 and minor Fe4Al13 were produced when Fe2Al5 dissolved. After 10 h of diffusion treatment, FeAl and α-Fe(Al) were the only two intermetallic phases left. Except FeAl2, the thickness of each intermetallic layer held good parabolic relationship with the diffusion annealing time.