<p>In this work, two compositions Fe<sub>72</sub>Si<sub>16</sub>B<sub>5</sub>Nb<sub>7</sub> and Fe<sub>75</sub>Si<sub>13</sub>B<sub>5</sub>Nb<sub>7</sub> were elaborated by mechanical alloying (MA) of the elemental high-purity powder mixture. The morphological, microstructural, and thermal properties were analyzed using scanning electron microscopy (SEM) attached with energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), and differential scanning calorimetry (DSC). The magnetic and hyperfine properties of the mixture elements during MA (0-64&#xa0;h) were investigated by vibrating sample magnetometer (VSM) and Mössbauer spectroscopy (MS). Structural analysis by Rietveld refinement of the XRD pattern of the samples milled 4&#xa0;h reveals the coexistence of various structures; Fe<sub>3</sub>Si, bcc-Fe, Fe<sub>23</sub>B<sub>6</sub>, and a small amount of Nb and Si, for the samples milled 16&#xa0;h 32&#xa0;h and 64&#xa0;h the that the structure became much more and more amorphous, and the amorphous phase becomes the dominant phase. The DSC of the annealing of sample Fe<sub>72</sub>Si<sub>16</sub>B<sub>5</sub>Nb<sub>7</sub> milled 64&#xa0;h shows that the crystallization of the amorphous phases, and the activation energy determined using Kissinger's equation was 611.84 ± 10&#xa0;KJ/mol. Mössbauer spectroscopy analysis confirmed a progressive amorphization of the material, accompanied by a reduction in the <i>α</i>-Fe crystalline phase content. In addition, for sample Fe<sub>75</sub>Si<sub>13</sub>B<sub>5</sub>Nb<sub>7</sub> milled 64&#xa0;h, the Mössbauer spectroscopy exhibits a paramagnetic doublet with a relatively small area fraction and a singlet, possibly assigned to the <i>γ</i>-Fe phase not detected by XRD. The VSM measurements show the hysteresis loops as a sigmoidal sharp, typically of nanomaterial or amorphous with little magnetic domain. The evolution of the coercivity and the saturation magnetization with milling time are discussed regarding different phenomena, such as residual stress, grain refinement, amorphous phase formation, surface anisotropy, defect density, and particle surface irregularities. </p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Microstructure, Thermal, and Magnetic Properties of Nanocrystalline/Amorphous Fe(Si,B,Nb) Powders Synthesized by Mechanical Alloying

  • Selma Khouiled,
  • Abdelhak Chebli,
  • Martin Cesnek,
  • Joan Josep Suñol,
  • Baris Avar

摘要

In this work, two compositions Fe72Si16B5Nb7 and Fe75Si13B5Nb7 were elaborated by mechanical alloying (MA) of the elemental high-purity powder mixture. The morphological, microstructural, and thermal properties were analyzed using scanning electron microscopy (SEM) attached with energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), and differential scanning calorimetry (DSC). The magnetic and hyperfine properties of the mixture elements during MA (0-64 h) were investigated by vibrating sample magnetometer (VSM) and Mössbauer spectroscopy (MS). Structural analysis by Rietveld refinement of the XRD pattern of the samples milled 4 h reveals the coexistence of various structures; Fe3Si, bcc-Fe, Fe23B6, and a small amount of Nb and Si, for the samples milled 16 h 32 h and 64 h the that the structure became much more and more amorphous, and the amorphous phase becomes the dominant phase. The DSC of the annealing of sample Fe72Si16B5Nb7 milled 64 h shows that the crystallization of the amorphous phases, and the activation energy determined using Kissinger's equation was 611.84 ± 10 KJ/mol. Mössbauer spectroscopy analysis confirmed a progressive amorphization of the material, accompanied by a reduction in the α-Fe crystalline phase content. In addition, for sample Fe75Si13B5Nb7 milled 64 h, the Mössbauer spectroscopy exhibits a paramagnetic doublet with a relatively small area fraction and a singlet, possibly assigned to the γ-Fe phase not detected by XRD. The VSM measurements show the hysteresis loops as a sigmoidal sharp, typically of nanomaterial or amorphous with little magnetic domain. The evolution of the coercivity and the saturation magnetization with milling time are discussed regarding different phenomena, such as residual stress, grain refinement, amorphous phase formation, surface anisotropy, defect density, and particle surface irregularities.