Structural, Thermal, Textural, and Magnetic Properties of Amorphous Mn–Cu–B Powder Synthesized by Mechanical Alloying

This work investigates the structural, thermal, textural, and magnetic properties of amorphous Mn 72 Cu 24 B 4 powder synthesized via mechanical alloying. X-ray diffraction confirmed a fully amorphous structure characterized by a broad diffuse halo at 2θ ≈ 45°. Scanning electron microscopy and energy-dispersive spectroscopy revealed irregular lamellar agglomerates below 10 μm with homogeneous elemental distribution. Differential scanning calorimetry revealed a multi-stage thermal transformation: a glass transition at T g ≈ 420 °C, followed by primary crystallization characterized by the first exothermic peak (onset at T x1 = 470 °C; peak at T p1 ≈ 550 °C), a secondary exothermic event at T x2 = 720 °C and peak at T p2 ≈ 750 °C, corresponding to boride precipitation, and an endothermic melting process (onset at T m,on = 935 °C; peak at T p,m = 975 °C). The supercooled liquid region ΔT x = 50 °C and γ parameter of 0.47 indicate moderate glass-forming ability and thermal stability. Nitrogen adsorption–desorption isotherms revealed a mesoporous structure with average pore diameter d p ≈ 4.6 nm and specific surface area S BET = 40 m 2 /g. Magnetic measurements at 300 K revealed ferromagnetic behavior with coercivity H c ≈ 47.8 kA/m (0.6 kOe), saturation magnetization M s ≈ 38 Am 2 /kg, remanent magnetization M r ≈ 2.5 Am 2 /kg, and remanence ratio M r /M s ≈ 0.066. The combination of structural stability, mesoporosity, and soft magnetic properties suggests potential applications in sensor and energy conversion technologies.