The structures and magnetic properties of Ti-substituted Pr_2(Fe,Co)_(14)(C,B)-type nanocomposites

摘要

The phase evolution, microstructure, and magnetic properties of Pr_xFe_(80-x)Ti_2Co_(10)B_4C_4 (x = 9,10.5) melt-spun ribbons were studied. All these ribbons consist mainly of three phases, namely, 2:14:1, alpha-(Fe,Co), and 2:17 phases. The _iH_c significantly increases and B_r slightly decreases with increasing Pr content. It was found that increasing Pr content from 9 to 10.5 at. percent leads to marked grain refinement in the ribbons. Increasing Pr content also helps suppress the formation of metastable 2:17 phase and the grain growth of the alpha-(Fe,Co) phase during the annealing treatment, thus avoiding the formation of extensive soft magnetic regions. The refined and uniform structure tends to enhance the exchange-coupling interaction between magnetic grains, which results in a significant improvement of the demagnetization-curve shape and magnetic properties accordingly. High coercivity _iH_c of 10.2 kOe, remanence B_r of 9.6 kG, and maximum energy product (BH)_(max) of 17.4 MG Oe have been achieved in Pr_(10.5)Fe(69.5)Ti_2Co_(10)B_4C_4 ribbons after optimal annealing.