| Due to the excellent soft magnetic properties and extensive application perspective of Fe-based nano-alloys, we have studied the preparation and the relationship between microstructure and magnetism of nanocrystalline FeSiBNbCu thin films, and the mechanical alloying behavior and the characteristics of the phase separation after subsequent heat treatment of Fe-Ni-Ge ternary system. The main results are as follows:1. Using radio frequency magnetron sputtering, we have successfully deposited FeSiBNbCu thin films with a-Fe(Si) nanocrystallite embedded in the amorphous matrix just by changing preparation parameters, without any post-annealing. High sputtering power was found to be an effective method to directly prepare nanocrystalline thin films with no heat treatment.2. The influence of the sputtering power on the microstructures of FeSiBNbCu thin films was investigated. The results showed that FeSiBNbCu thin films were mostly amorphous when deposited with low sputtering power. As the sputtering power was high, a-Fe(Si) and a-Fe(B) nanocrystallites separated out from the amorphous matrix and were highly oriented along Fe(110) plane. Thus the embedded structure was directly formed without thermal annealing. With increasing the sputtering power, the volume fractions of crystalline phases increased whereas the amorphous phase correspondingly decreased. However, in the range of the sputtering power from 100 to 150W the growth of nanocrystallites dominated during the variation in the microstructure of the thin film whereas the volume fractions of nanocrystallites remained almost unchanged. The occupation probability of the B atoms around the Fe atom in the a-Fe(B) phase also increased with the sputtering power, consequently leading to the reduction of the hyperfine field of the a-Fe(B) phase. For the sputtering power of 50, 100, 150 and 200W, the corresponding hyperfine fields of the a-Fe(B) phase were 235, 229, 223 and 218kOe, respectively.3. The microstructure had a distinct effect on the orientation of magnetic moments in FeSiBNbCu thin films. It has been found that the angle β included between the orientation of magnetic moments and the normal to the film plane varied with the microstructure of the thin film. When the thin film was mainly of theamorphous structure, the orientation of magnetic moments was almost parallel to the film plane. With the formation of nanocrystalline embedded structure, the angle included between the magnetic moment orientation and the normal to the film plane gradually reduced. However, the magnetic moment orientation hardly changed with the growth of nanocrystallites in the thin film.4. The alloying behavior of Fe-Ni-Ge ternary system was discussed by mechanical alloying. When the milling time was short, the sample consisted of fcc-Ge solid solution, bcc-Fe(Ni), bcc-Fe(Ge) solid solutions, bcc-Fe disordered solid solution and the Ni-rich FeNiGe paramagnetic phase. As the milling time was prolonged, fcc-Ge solid solution disappeared, and the atomic configurations of the other phases also changed. The relative content of the paramagnetic phase decreased with increasing the milling time, while that of ferromagnetic phases, including bcc-Fe(Ni), bcc-Fe(Ge) solid solutions and bcc-Fe disordered solid solution, correspondingly increased. The average hyperfine field of the sample increased from 160.90kOe to 178.93kOe with increasing the milling time from 50h to 70h. The saturation magnetization of the sample had the same variation trend.5. During the annealing process of the ball-milled sample, the phase composition changed. The study on the characteristics of the phase separation indicated that after heat treatment there coexisted two phases, namely, the Ni-rich FeNiGe paramagnetic phase and Ni-poor FeNiGe ferromagnetic phase. These two phases were both of Fe3Ge2-like B82 hexagonal structure. For the Ni-poor FeNiGe phase, the number of the Ni atoms that occupied the 2d site was very small, so that this Ni-poor phase was still ferromagnetic, which was the same as the Fe3Ge2 phase...
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