Surface modification engineering of iron-silicon-aluminum alloys: Microstructure evolution investigation and microwave absorption enhancement

Abstract

Developing highly efficient electromagnetic (EM) absorbers with a broad bandwidth remains a major challenge for reducing EM pollution originating from the ever-rising electronic and telecommunication devices. Designing core-shell structures containing a magnetic core and dielectric shell could be an effective strategy to tackle this problem. Herein, we report a surface modification strategy to synthesize the FeSiAl/phosphate core-shell materials with unique rodlike structure through a facile surface passivation process. Multilevel phosphate shells are in situ introduced for significantly facilitating the EM absorbing performance by inducing multiple interfacial polarizations and obtain ideal impedance matching. Direct evidence of the morphology and microstructure evolution of resultant FeSiAl/phosphate composites correlated to the EM properties has been systematically investigated. Due to intense synergistic effects between magnetic and dielectric loss, exceptional microwave dissipation capacity can be achieved over an ultra-wide absorption bandwidth of 9.8 GHz at 2.5 mm. • The microstructure evolution at high temperatures has been elaborated at different scales by the focused ion beam technology. • Core-shell structure enhanced the dielectric loss ability by inducing multiple interfacial polarizations and achieved ideal impedance matching. • Superb dissipation capacity has been achieved over an ultra-wide range of 9.8 GHz attributed to the magnetic-dielectric synergistic effects.