Effect of crystallization on the structural and magnetic properties of amorphous Mn–Cu–B powder

This work examines the structural, thermal, textural, and magnetic properties of amorphous Mn₇₂Cu₂₄B₄ powder produced by mechanical alloying. X-ray diffraction confirmed a fully amorphous structure with a broad halo at 2θ ≈ 45°. Electron microscopy revealed irregular lamellar agglomerates below 10 μm with homogeneous elemental distribution. Thermal analysis showed a glass transition at Tg ≈ 420°C, primary crystallization (onset Tx₁ = 470°C), a secondary exothermic event related to boride precipitation (Tx₂ = 720°C), and an endothermic melting process (onset Tm,on = 935°C). The supercooled liquid region (ΔTx = 50°C) and γ parameter (0.47) indicate moderate glass-forming ability. Nitrogen adsorption revealed a mesoporous structure with average pore diameter of 4.6 nm and surface area of 40 m²/g. Magnetic measurements at 300 K showed ferromagnetic behaviour with coercivity of 47.8 kA/m, saturation magnetisation of 38 Am²/kg, and remanence ratio of 0.066. The combination of structural stability, mesoporosity, and soft magnetic properties suggests potential for sensors and energy conversion applications.