Coercivity mechanism and magnetization reversal process in nanocomposite Pr${}_2$Fe${}_{14}$B/α-Fe alloy with phosphorous addition

An investigation is conducted for the coercivity mechanism in as-spun Pr${}_2$Fe${}_{14}$B/α-Fe ribbons containing different phosphorus (P) prepared at a wheel speed of 30 ms${}^{-1}$. With the increase of P addition, the volume of the amorphous phase in the ribbons is increased, and the grain size of Pr${}_2$Fe${}_{14}$B is decreased. The hysteresis loops of the ribbons with 0.1 at% P exhibit a homogeneous magnetization reversal process similar to single-phase magnet, demonstrating that soft magnetic grains are fully coupled with the hard ones. The highest coercivity of 12.0 kOe (300 K)-38.0 kOe (100 K) is achieved in the ribbon with 0.3 at% P-addition, which shows weak exchange coupling interaction between grains, and the high coercivity comes mainly from the decoupled hard phase. The values of the microstructure parameter α${}_k$α${}_{ex}$ in all compositions are less than 0.3 and imply that the main coercivity mechanism is the mixture of the nucleation of reverse domain and domain wall pinning. The minor hysteresis loops and initial magnetization curves show the dominant domain wall pinning in the ribbon with 0-0.1 at% P, nucleation and pinning in the ribbon with 0.3 at% P, and dominant domain nucleation in the ribbon with 0.5 at% P. (© 2023 Wiley‐VCH GmbH)