The Effect of High-Temperature Annealing on the Magnetic and Structural Properties of (MnFePSi)-Based Glass-Coated Microwires

In this paper, the impact of annealing at different temperatures (973 K, 1073 K, and 1123 K for 1 h) on the magnetic and microstructural properties of MnFePSi-based glass-coated microwires is studied. Annealing significantly influences the magnetic and microstructural properties of Mn–Fe–P–Si glass-coated microwires. XRD analysis reveals that increasing the annealing temperature leads to a notable increase in the Fe2P phase content, reaching a maximum at 1123 K, while simultaneously reducing the presence of secondary phases observed in the as-prepared sample. The reduction in secondary phases in Mn–Fe–P–Si-based microwires, grain size, and internal stress relaxation have a profound impact on their magnetic behavior. High coercivity values are observed in both the as-prepared and annealed samples. However, annealing at higher temperatures (1073 K and 1123 K) results in a significant reduction in coercivity, decreasing from 1200 Oe for the sample annealed at 973 K to 300 Oe and 150 Oe, respectively. In addition, the sample annealed at 1123 K for 1 h shows a notable paramagnetic behavior for loops measured from 200 K to 300 K. Meanwhile, the other samples show ferromagnetic behavior for all measured temperatures from 5 to 300 K. This study highlights the significant potential for tailoring and modifying various magnetic properties of Mn–Fe–P–Si glass-coated microwires, including metamagnetic phase transitions, magnetic behavior, and the control of magnetic response (hardness/softness). Such tailored properties make Mn–Fe–P–Si glass-coated microwires promising candidates for a wide range of applications.