Effect of Ga, Si and Nb additions on the phases and magnetic properties of melt-spun Nd-Fe-B alloys

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

“…The effect of niobium additions on the microstructure of Nd-Fe-B magnets has been intensively studied (Baily and Harris 1985, Parker et al 1987a, b, Tokunaga et al 1987a, c, Xiao Y et al 1987b, Yoneyama et al 1987, Schrey 1988, Zhou G F et al 1988, Allibert 1989, Rodewald and Wall 1989, Withey et al 1989, Hirosawa et al 1990c, Tenaud et al 1990a, Zhou S X et al 1990, Freeman et al 1991, Bala et al 1992, Jinfang 1992, Ahmed et al 1994, Seeger et al 1994. Different Nb-containing phases were reported in the literature.…”

“…The Nb 26 Fe 32 B 42 ternary phase was found to originate (nucleate) in the heart of the free iron phase which provides strong evidence for the role of Nb in the removal of free iron from microstructure. Nb-containing precipitates prevent matrix grains from growing or making possible nucleation sites during solidification (Tokunaga et al 1987b, Rodewald and Wall 1989, Zhou S X et al 1990, Jinfang et al 1992.…”

“…Used in combination with other elements, for example, Dy and/or Co additions, Nb has been shown to significantly increase the coercivity of Nd-Fe-B-based magnets (Bailey and Harris 1985, Tokunaga et al 1987b, Xiao et al 1987b, Yoneyama et al 1987, Withey et al 1989, 1992, Zhou S X et al 1990. In Nb-and (NbGa)-containing (NdDy)-(FeCo)-B magnets, a phase (Fe,Co)NbB, having CoNbB-type orthorhombic structure was found (Zhou G F et al 1988, Bala et al 1992.…”