Abstract:A binary Fe-Al alloyed layer was synthesized on 45 steel by means of double glow plasma surface alloying technique. The corrosion-resisting layer prepared is composed of a sedimentary layer and a diffusion layer, with a total thickness of about 180 μm. The aluminum content of the alloyed layer shows gradual change from surface to the inside of substrate. The ideal profile is beneficial to the metallurgical bonding of the surface alloying layer with substrate materials. The microstructure of both layers consists of the Fe-Al intermetallic compound, which is FeAl with B2 structure in the sedimentary layer and Fe₃Al with incompletely ordered DO₃ structure in the diffusion layer. The protective film exhibits high micro-hardness. In comparison with the substrate of 45 steel, the corrosion resistance of the aluminized sample is much higher in 2.0% Na₂S and 0.05 mol/L Na₂SO₄ + 0.5 mol/L NaCl mixed solutions.

Key words: plasma surface alloying; Fe-Al intermetallic; 45 steel; corrosion resistance