Enhanced corrosion resistance of Fe40Ni38Mo4B18 and Nd15Fe77B8 by laser glazing

Laser glazing, using a KrF excimer laser (> = 248 nm, >a = 22 ns), has been used to improve the corrosion resistance properties of crystallized Fe40Ni38Mo4B18 (Metglas 2826 MB) and the permanent magnet material Nd15Fe77B8. The formation of an amorphous layer was confirmed by conversion-electron Mossbauer Spectroscopy (CEMS), and the thickness of the amorphous layer was determined from the attenuation of the x-rays diffracted from the underlying crystalline material. The variation with laser fluence of the amorphous layer thickness on the Metglas were measured. The corrosion properties of the original, crystalline and laser glazed Metglas were measured potentiodynamically in acid electrolyte. Similar voltametric characteristics were obtained for the laser glazed surface and original Metglas, both showing a lower current in the passive region than the crystalline material. Laser glazing of the Nd15Fe77B8 also produced a significant reduction in the rate of corrosion in base and neutral solutions