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Autori: V. Pop, O. Isnard, I. Chicinaş
Editorial: Journal of Alloys and Compounds, 361, p.144-152, 2003.
The progressive synthesis of the nanocrystalline Ni3Fe intermetallic compound by mechanical alloying of iron and nickel powders and annealing is discussed. The samples, milled under argon atmosphere for 1-24 h, were annealed for 30 min at 300 C and for 1, 2, 3, 8 and 12 h at 330 8C. The formation of the Ni3Fe intermetallic compound was observed by X-ray diffraction and magnetic measurements. Magnetic measurements were performed in a magnetic field up to 8 Tesla between 4 and 300 K. After 4 h of milling, the presence of the Ni3Fe phase is observed in the X-rays diagrams. The Ni Fe intermetallic compound is obtained after 8-10 h of milling. The heat treatment relaxes the first and second order internal stresses and favours the solid-state reaction. A Ni-Fe solid solution is observed after 1h of milling followed by annealing. The beginning of the Ni Fe phase formation was clearly performed by annealing after 3 h of milling. The annealing influence on the Ni Fe phase formation is more effective for lower annealing times. The mean size of the crystallites, after 12 h of milling and 3 h of annealing at 330 8C, is 22 +-2 nm. In order to discuss the influence of the synthesis conditions on the Ni3Fe phase formation in the whole sample, a milling-annealing-transformation (MAT) diagram is proposed.
Cuvinte cheie: Transition metal alloys; Nanostructured materials; Mechanical alloying; X-ray diffraction; Magnetic measurements