Effect of C on Phase Evolution, Microstructure, and Magnetic Properties of Pr2Fe14B-Type Nanocomposites Original Research Article

The phase evolution, microstructure and magnetic properties of melt-spun Pr-rich Pr11Febal.B8-yCy (y = 0–8) and Pr-lean Pr9Febal.TixB11–yCy (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 Pr11Febal.B8–yCy nanocomposites. C atoms prefers to enter 2:14:1 phase in forming Pr2Fe14(B, C). But the volume fraction of Pr2Fe17Cz, α-Fe and 1:2 carbide increases, due to the dissociation of 2:14:1 phase and the suppression of Fe3B phase, with further increase of carbon content. The optimal magnetic properties of Br = 9.4 kG, iHc = 9.3 kOe, and (BH)max = 17.3 MGOe were obtained for Pr11Febal.B6C2. In contrast, the increase of C substitution in Pr9Febal.Ti2.5B11–yCy (y=0–11) ribbons degrades the Br, iHc, and (BH)max monotonically, which is arisen from the increase of vol % of Pr2Fe17Cz and α-Fe phases, and the rapid decrease of 2:14:1 phase. In comparison with those of Pr9Febal.B11–yCy (y=0–5.5) ribbons, improved magnetic properties of (BH)max=15.3–17.8 MGOe with higher coercivity of iHc=9.7–10.8 kOe have been obtained in Ti-containing Pr9Febal.Ti2.5B11–yCy (y=0–5.5) ribbons. However, in higher Ti concentration Pr9Febal.Ti4B11–yCy, 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 Br = 9.4 kG, iHc = 11.1 kOe, (BH)max = 18.0 MGOe and α = −0.146 %/°C, β = −0.576 %/°C were achieved in Pr9Febal.Ti4B10.5C0.5 nanocomposites.