Phase evolution and magnetic properties of Pr xFe 82− x− yTi yCo 10B 4C 4 ( x = 9–10.5; y = 0, 2) nanocomposites

Abstract

The phase evolution and magnetic properties of Pr x Fe 82− x− y Ti y Co 10B 4C 4 ( x = 9–10.5; y = 0, 2) melt-spun ribbons have been investigated. The effects of wheel speed and annealing on the crystallization and magnetic properties of the ribbons are discussed in detail. It was found that Ti substitution enhances the glass forming ability of the Pr 2(Fe, Co) 14(C, B)-type ribbons. For a high wheel speed V s (18 m/s), the Ti-substitution ribbons consist of a significant fraction of amorphous phase, and show typical two-step magnetic behavior, while most of the Ti-free ribbons are mainly composed of the crystalline 2:14:1, α-(Fe, Co) and 2:17 phases. With decreasing wheel speed, all ribbons are fully crystallized, and a larger fraction of the magnetically hard 2:14:1 phase is formed. The content of metastable 2:17 phase in the ribbons decreases with increasing Pr and Ti substitution. A B r of 9.5 kG, i H c of 9.8 kOe, and ( BH) max of 16.0 MGOe were obtained in the as-spun Ti-substituted Pr 10.5Fe 69.5Ti 2Co 10B 4C 4 ribbon prepared at V s = 15 m/s. For all the as-spun, Ti-free ribbons prepared at various V s, the ( BH) max is lower than 10 MGOe owing to a poor shape of the demagnetization curve. Ti substitution also helps suppress the grain growth of 2:17 phase during the annealing process, and simultaneously promotes the growth of magnetically hard 2:14:1 phase. The annealing treatment significantly improves the magnetic properties of the Ti-substituted ribbons with higher Pr contents. No obvious improvement of magnetic properties was found in the Ti-free ribbons after annealing.