Nickel Powders Modified Nanocoating Strengthened Iron Plates by Surface Mechanical Attrition Alloy and Heat Treatment

Added with Ni powders, an enhanced thick Fe-Ni alloy nanocoating was fabricated mechanically on pure iron plate by using cycling surface mechanical attrition alloy treatment (SMAAT). The nanocoatings were analyzed and characterized by optical microscope (OM), X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectra. The hardness of the nanocoating was tested. Owing to the combination of deposition, wear, deformation and defect-enhanced diffusion processes, the repeated heat treatment combined with SMAAT can effectively increase the thickness and improve the performance of the nanocoatings. The process not only refined the surface crystallinity of Fe-Ni alloy, but also promoted the fabrication of the FeNi3 and NiFe2O4 alloy phases. As a result, the average thickness of the nancoatings has been doubled after the process of 3-cycle treatment. The microhardness in the near-surface region and bonding between coating and target was considerably enhanced.