Highly enhanced microwave absorption properties of CoFeBSiNb metallic glasses through corrosion

Highlights: • The CoFeBSiNb soft magnetic MGPs with porous surface structures were obtained. • The permittivity increases obviously due to the increase of specific surface area. • The MGPs with zero magnetostriction exhibit strong microwave absorption properties. The CoFeBSiNb soft magnetic metallic glasses with strong glass forming ability were selected as microwave absorption materials for the first time. The metallic glass powders (MGPs) were prepared through milling and hydrochloric acid treatments. The effects of mass fraction of MGPs in wax composites and corrosion treatment on the microwave absorbing properties were investigated in details. The results demonstrated that the complex permittivity and permeability of the composites increased gradually as the MGPs mass fraction increased. Through chemical corrosion, the complex permittivity of the metallic glasses apparently increased, which due to the strengthened interfacial polarization caused by the porous surface structures. As a result, the minimum value of reflection loss (RL) for the composites containing 60 wt% of MGPs corroded for one hour under pH = 2 reached −45.2 dB at 14.64 GHz with a thickness of only 2.3 mm and the bandwidth reached 14 GHz for RL < −10 dB or 6.2 GHz for RL < −20 dB.