Amorphous iron nanoparticles formed on aluminum surfaces during thermomechanical treatment

•After thermomechanical treatment, Fe nanoparticles were observed on AA1100 surface.•The Fe nanoparticles possessed an amorphous microstructure.•Fe nanoparticles were linked to intermetallic particle debris on the surface.

Iron nanoparticles were observed on the surface of commercial purity aluminum alloys after thermomechanical treatment using a hot rolling tribo-simulator with a roll surface roughness (Ra) of 0.01 µm. These nanoparticles were spherical in shape and possessed an amorphous structure. They were observed lying on the oxide layer of the alloy surface and on crack faces. Iron nanoparticles have not been previously reported on aluminum surfaces under this thermomechanical condition. The surface of the hot rolled aluminum alloy was also covered with fractured iron-rich intermetallic particles embedded into the surface and caught within cracks.