The structures and magnetic properties of Ti-substituted Pr2(Fe,Co)14(C,B)-type nanocomposites

Abstract

The phase evolution, microstructure, and magnetic properties of ${\mathrm{Pr}}_x{\mathrm{Fe}}_{80-x}{\mathrm{Ti}}_2{\mathrm{Co}}_{10}{\mathrm{B}}_4{\mathrm{C}}_4$ $(x=9,10.5)$ melt-spun ribbons were studied. All these ribbons consist mainly of three phases, namely, 2:14:1, $\alpha \text{-}(\mathrm{Fe},\mathrm{Co})$ , and 2:17 phases. The ${}_{i}H_c$ significantly increases and $B_r$ slightly decreases with increasing Pr content. It was found that increasing Pr content from $9\text{to}10.5\mathrm{at.}\%$ 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 $\alpha \text{-}(\mathrm{Fe},\mathrm{Co})$ 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 ${}_{i}H_c$ of $10.2\mathrm{kOe}$ , remanence $B_r$ of $9.6\mathrm{kG}$ , and maximum energy product ${\left(BH\right)}_{\max }$ of $17.4\mathrm{MG}\mathrm{Oe}$ have been achieved in ${\mathrm{Pr}}_{10.5}{\mathrm{Fe}}_{69.5}{\mathrm{Ti}}_2{\mathrm{Co}}_{10}{\mathrm{B}}_4{\mathrm{C}}_4$ ribbons after optimal annealing.