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<p>This work investigates the structural, thermal, textural, and magnetic properties of amorphous Mn<sub>72</sub>Cu<sub>24</sub>B<sub>4</sub> 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&#xa0;μm with homogeneous elemental distribution. Differential scanning calorimetry revealed a multi-stage thermal transformation: a glass transition at T<sub>g</sub> ≈ 420&#xa0;°C, followed by primary crystallization characterized by the first exothermic peak (onset at T<sub>x1</sub> = 470&#xa0;°C; peak at T<sub>p1</sub> ≈ 550&#xa0;°C), a secondary exothermic event at T<sub>x2</sub> = 720&#xa0;°C and peak at T<sub>p2</sub> ≈ 750&#xa0;°C, corresponding to boride precipitation, and an endothermic melting process (onset at T<sub>m,on</sub> = 935&#xa0;°C; peak at T<sub>p,m</sub> = 975&#xa0;°C). The supercooled liquid region ΔT<sub>x</sub> = 50&#xa0;°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<sub>p</sub> ≈ 4.6&#xa0;nm and specific surface area S<sub>BET</sub> = 40&#xa0;m<sup>2</sup>/g. Magnetic measurements at 300&#xa0;K revealed ferromagnetic behavior with coercivity H<sub>c</sub> ≈ 47.8 kA/m (0.6 kOe), saturation magnetization M<sub>s</sub> ≈ 38&#xa0;Am<sup>2</sup>/kg, remanent magnetization M<sub>r</sub> ≈ 2.5&#xa0;Am<sup>2</sup>/kg, and remanence ratio M<sub>r</sub>/M<sub>s</sub> ≈ 0.066. The combination of structural stability, mesoporosity, and soft magnetic properties suggests potential applications in sensor and energy conversion technologies.</p>

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

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  • 发表日期：

    2026年4月16日

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  • Luciano Nascimento

摘要

This work investigates the structural, thermal, textural, and magnetic properties of amorphous Mn72Cu24B4 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 Tg ≈ 420 °C, followed by primary crystallization characterized by the first exothermic peak (onset at Tx1 = 470 °C; peak at Tp1 ≈ 550 °C), a secondary exothermic event at Tx2 = 720 °C and peak at Tp2 ≈ 750 °C, corresponding to boride precipitation, and an endothermic melting process (onset at Tm,on = 935 °C; peak at Tp,m = 975 °C). The supercooled liquid region ΔTx = 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 dp ≈ 4.6 nm and specific surface area SBET = 40 m2/g. Magnetic measurements at 300 K revealed ferromagnetic behavior with coercivity Hc ≈ 47.8 kA/m (0.6 kOe), saturation magnetization Ms ≈ 38 Am2/kg, remanent magnetization Mr ≈ 2.5 Am2/kg, and remanence ratio Mr/Ms ≈ 0.066. The combination of structural stability, mesoporosity, and soft magnetic properties suggests potential applications in sensor and energy conversion technologies.