The magnetic anisotropy of Fe 25 Ni 75 nanocrystallites in the range of 10～20 nm was measured by the law of approach to saturation. The samples were prepared by mechanical alloying process, and the average ...The magnetic anisotropy of Fe 25 Ni 75 nanocrystallites in the range of 10～20 nm was measured by the law of approach to saturation. The samples were prepared by mechanical alloying process, and the average crystal size was determined by X ray diffraction. The effective magnetic anisotropy of these fine particles is found in an order of 10 6 erg/cm 3 that is much greater than that of normal crystal size of particles. The dependence of magnetic anisotropy on the particle size was studied. It has been demonstrated that the strain anisotropy occupies the most of the total magnetic anisotropy, and the internal strain is a critical factor for their magnetic properties.展开更多
Fe 100- x Ni x alloys of ultrafine particle with the average grain size of about 10 nm were synthesized by mechanically alloying process. The samples were investigated by X ray diffraction and measure...Fe 100- x Ni x alloys of ultrafine particle with the average grain size of about 10 nm were synthesized by mechanically alloying process. The samples were investigated by X ray diffraction and measurements of the saturation magnetization and coercivity force. Both b.c.c and f.c.c phase exist within a wide range for Fe 100- x Ni x , while x ≤45. The effective magnetic anisotropy K e was measured by applying the law of approach to saturation. The value of K e decreases with an increase of Ni content. It is noticed that the strain anisotropy makes a large contribution to the magnetic anisotropy. The estimation of grain size leads to the determination of the single domain critical size and domain wall energy. The exchange stiffness and exchange integral deduced from the relationship between the effective magnetic anisotropy and domain wall energy are in agreement with that calculated by other methods.展开更多
文摘The magnetic anisotropy of Fe 25 Ni 75 nanocrystallites in the range of 10～20 nm was measured by the law of approach to saturation. The samples were prepared by mechanical alloying process, and the average crystal size was determined by X ray diffraction. The effective magnetic anisotropy of these fine particles is found in an order of 10 6 erg/cm 3 that is much greater than that of normal crystal size of particles. The dependence of magnetic anisotropy on the particle size was studied. It has been demonstrated that the strain anisotropy occupies the most of the total magnetic anisotropy, and the internal strain is a critical factor for their magnetic properties.
文摘Fe 100- x Ni x alloys of ultrafine particle with the average grain size of about 10 nm were synthesized by mechanically alloying process. The samples were investigated by X ray diffraction and measurements of the saturation magnetization and coercivity force. Both b.c.c and f.c.c phase exist within a wide range for Fe 100- x Ni x , while x ≤45. The effective magnetic anisotropy K e was measured by applying the law of approach to saturation. The value of K e decreases with an increase of Ni content. It is noticed that the strain anisotropy makes a large contribution to the magnetic anisotropy. The estimation of grain size leads to the determination of the single domain critical size and domain wall energy. The exchange stiffness and exchange integral deduced from the relationship between the effective magnetic anisotropy and domain wall energy are in agreement with that calculated by other methods.
