Surface functionalization of carbonyl iron with aluminum phosphate coating toward enhanced anti-oxidative ability and microwave absorption properties

•AlPO4 layer has been succesfully deposited on the surface of carbonyl iron.•AlPO4 layer can improve the anti-oxidative ability of carbonyl iron significantly.•The presence of AlPO4 layer can optimize the matching of characteristic impedance.•Fe@AlPO4 composites exhibit substantially enhanced microwave absorption properties.•The anit-oxidative AlPO4 layer endows Fe@AlPO4 composites with durable performance.