Forming Ability of the 2-14-1 Phase in Melt-Spun Fe-Nd-(C, B) Alloys

The forming ability of the Nd2Fe14(C, B) phase was investigated in melt-spun Fe90-zNd10(C, B)(z) (z=3, 5, 7, 9) alloys in which the ratio of carbon to boron was changed. The cooling rate of the molten sample was varied by changing the surface velocity of a single roller apparatus. It was confirmed that the substitution of a small amount of boron promotes the formation of the 2-14-1 phase in the samples z = 3 to 7. The 2-14-1 phase is formed instead of Nd2Fe17Cx phase with the substitution of 1 mol% boron abruptly. With increasing boron substitution, the Curie temperature of the 2-14-1 phase increases from 533 to 586 K, indicating the boron replacement of carbon in the 2-14-1 phase. On the other hand, in the alloys of the samples z = 9, the volume fraction of the 2-14-1 phase increases with increasing boron substitution gradually, and the Curie temperature of the phase is almost constant (586 K) regardless of the ratio of carbon to boron in the alloys. The result indicates that carbon atoms are scarcely dissolved in the 2-14-1 phase. The magnetic properties are improved by the substitution of 15 to 40% carbon for boron as compared with the ternary Nd-Fe-B alloys. The (BH)(max) value reaches maximal 136 kJ/m(3) in the sample Fe83Nd10CB6.