Effect of C on Phase Evolution, Microstructure, and Magnetic Properties of Pr 2Fe 14B-Type Nanocomposites

Abstract

The phase evolution, microstructure and magnetic properties of melt-spun Pr-rich Pr 11Fe bal.B 8- y C y ( y = 0–8) and Pr-lean Pr 9Fe bal.Ti x B 11– y C y ( x = 0, 2.5 and 4; y = 0–11) ribbons have been investigated intensively. A slight substitution of C for B ( y=2) was proven to be effective in improving the magnetic properties of Pr-rich Pr 11Fe bal.B 8– y C y nanocomposites. C atoms prefers to enter 2:14:1 phase in forming Pr 2Fe 14(B, C). But the volume fraction of Pr 2Fe 17C z , α-Fe and 1:2 carbide increases, due to the dissociation of 2:14:1 phase and the suppression of Fe 3B phase, with further increase of carbon content. The optimal magnetic properties of B r = 9.4 kG, i H c = 9.3 kOe, and ( BH) max = 17.3 MGOe were obtained for Pr 11Fe bal.B 6C 2. In contrast, the increase of C substitution in Pr 9Fe bal.Ti 2.5B 11– y C y ( y=0–11) ribbons degrades the B r, i H c, and ( BH) max monotonically, which is arisen from the increase of vol % of Pr 2Fe 17C z and α-Fe phases, and the rapid decrease of 2:14:1 phase. In comparison with those of Pr 9Fe bal.B 11– y C y ( y=0–5.5) ribbons, improved magnetic properties of ( BH) max=15.3–17.8 MGOe with higher coercivity of iH c=9.7–10.8 kOe have been obtained in Ti-containing Pr 9Fe bal.Ti 2.5B 11– y C y ( y=0–5.5) ribbons. However, in higher Ti concentration Pr 9Fe bal.Ti 4B 11– y C y , ribbons, a slight substitution of C for B ( y = 0.5–1) is beneficial in improving the coercivity and magnetic energy product, simultaneously. The optimal properties of B r = 9.4 kG, i H c = 11.1 kOe, ( BH) max = 18.0 MGOe and α = −0.146 %/°C, β = −0.576 %/°C were achieved in Pr 9Fe bal.Ti 4B 10.5C 0.5 nanocomposites.