Vanadium influence in NdFeBAl melt-spun magnets

Permanent magnets based on R-Fe-B and R-Fe-C alloys

“…No galvanic corrosion takes place in these magnets, owing to the negligible small difference of corrosion potentials (Shimotomai et al 1994). The improvement of the corrosion resistance was also found with the addition of Nb, Al (Le Breton and Teillet 1991), Cr, Co, Al and Nb (Szymura et al 1991b, Dy and Al (Kim and Jacobson 1987), Ga (Knoch et al 1990, Grieb et al 1991b, V and Al (Tanguy et al 1996), Cu (Szymura et al 1993) as well as other elements. The refractory boride phases, linking the magnetic grain, first prevent the corrosion diffusion through the Nd-rich phase, and then the release of the surface magnetic grain from the bulk magnet (Tenaud et al 1991, Kobe-Besenicar et al 1994.…”

“…Research was also performed on the effects of alloying elements in diminishing the corrosion and oxidation behaviour of Nd-Fe-B permanent magnets (Jacobson and Kim 1987, Tokunaga et al 1987b, Van Mens et al 1987, Chin et al 1988a, Doser and Keeler 1988, Balla et al 1990b, c, Kim et al 1990, Knoch et al 1990, Shimotomai et al 1990, Tenaud et al 1990a, Zhou G F et al 1990c, Grieb et al 1989b, Hirosawa et al 1991a, Le Breton and Teillet 1991, Szymura et al 1991a, c, Tokuhara and Hirosawa 1991, Kobe-Besenicar et al 1994, Shimotomai 1994, Tanguy et al 1996. The corrosion resistance is improved by stabilization of the Nd-rich grain boundary phase by addition of alloying elements.…”