Orateur
Description
Structure, hyperfine, thermal stability, and magnetic properties of the mechanically alloyed Fe47.5Co50Ni2.5 (Fe47.5) and Fe50Co47.5Ni2.5 (Fe50) powders were investigated by using X-ray diffraction (XRD), 57Fe Mössbauer spectrometry, differential scanning calorimetry, and vibrating sample magnetometer, respectively. The XRD results show the existence of bcc α-Fe type, bcc FeCo, and hcp Co-type structures. 57Fe Mössbauer spectrometry confirms the formation of Fe- and Co-rich environments. The average hyperfine magnetic field and the saturation magnetization exhibit different behaviors up to 24 h but a similar trend after 48 h of milling for both samples. The variation of the coercivity is different up to 12 h of milling but identical after 24 h of milling for both samples. The addition of 2.5wt.%Ni lowers the disordered-to-ordered (Tα→α′) and α → γ (Tα→γ) phase transformation temperatures. The structure of ball-milled and heat-treated samples consists of bcc α-Fe type (a = 0.2864–0.2874 nm) and FeCo (a = 0.2853–0.2858 nm) phases with crystallite sizes of approximately 39–54 nm. The saturation magnetization increases to about 201–220 emu/g, and the coercivity decreases to approximately 35–57 Oe after thermal annealing. According to the squareness Mr/Ms ratio, the as-milled and heat-treated powders are multidomain.
| Affiliation de l'auteur principal | Laboratoire de magnétisme et de spectroscopie des solides (LM2S)- Faculty of Science- Department of Physics- Badji Mokhtar University |
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