Structure and Magnetic Properties of Hot Pressed NiFe Powder

The aim of this work is to investigate the structure and magnetic properties of compacted microcrystalline NiFe (81 wt.% of Ni) powder. Bulk samples were prepared by compaction of milled NiFe (81 wt.% of Ni) ribbon. We found that after compaction of the powder displacement of domain walls becomes more dominant and the coercivity decreases and is comparable with the coercivity of conventional permalloy. The coercivity of the bulk material before heat treatment is lower than that for powder and that is why we can assume that the magnetic "contact" is restored after compaction. Annealing of bulk samples reduces the losses due to the relaxation of internal stresses induced by milling and compaction

Low Frequency Core Losses Components of FeNiMo Powder Compacted Materials

The relations of core losses with the frequency of FeNiMo alloys were investigated. The core energy losses were determined by the measurements of dc and ac hysteresis loops as functions of frequency (1 Hz-50 Hz). The usual three-component concept of separation of core losses consisting of hysteresis, eddy current and anomalous losses was used to explain the influence of the powder particle size on core loss frequency dependences

Soft Magnetic Properties in Bulk Permalloy Alloys Fabricated by a Warm Consolidation

Soft magnetic properties of bulk NiFe and NiFeMo alloys consolidated by hot compaction were studied. During annealing the compacts residual stresses diminish by relaxation and soft magnetic properties improve. The lowest coercivity of bulk NiFe and NiFeMo alloys are 11. 0 and 11. 2 A/m, respectively, while the total losses are 1. 81 and 1. 42 W/g at f=10 kHz and $B_\text{max}$ =0. 2 T

Magnetic Properties of Crystalline NiFe Alloy Prepared by High-Energy Ball Milling and Compacting

The structure and magnetic properties of compacted microcrystalline NiFe (81 wt% of Ni) powder is investigated. The powder of NiFe alloy prepared by ball milling of ribbon (prepared by melt spinning) remains single phase material suitable for compaction in order to prepare soft magnetic material. The bulk samples were consolidated by uniaxial compaction of the powder in vacuum. By measuring of AC and DC magnetic properties it was found out that in bulk samples the displacement of domain walls is the dominant magnetization process, while rotation of magnetization vectors prevails in powder material

Structure and Magnetic Properties of Hot Pressed NiFe Powder

The aim of this work is to investigate the structure and magnetic properties of compacted microcrystalline NiFe (81 wt. % of Ni) powder. Bulk samples were prepared by compaction of milled NiFe (81 wt. % of Ni) ribbon. We found that after compaction of the powder displacement of domain walls becomes more dominant and the coercivity decreases and is comparable with the coercivity of conventional permalloy. The coercivity of the bulk material before heat treatment is lower than that for powder and that is why we can assume that the magnetic "contact" is restored after compaction. Annealing of bulk samples reduces the losses due to the relaxation of internal stresses induced by milling and compaction

Magnetic Properties of Crystalline NiFe Alloy Prepared by High-Energy Ball Milling and Compacting

The structure and magnetic properties of compacted microcrystalline NiFe (81 wt% of Ni) powder is investigated. The powder of NiFe alloy prepared by ball milling of ribbon (prepared by melt spinning) remains single phase material suitable for compaction in order to prepare soft magnetic material. The bulk samples were consolidated by uniaxial compaction of the powder in vacuum. By measuring of AC and DC magnetic properties it was found out that in bulk samples the displacement of domain walls is the dominant magnetization process, while rotation of magnetization vectors prevails in powder material

Isobaric Thermal Expansion and Isothermal Compression of Powdered NiFe Based Alloys Studied by In-Situ EDXRD

The aim of the present work was to study the isothermal compression and isobaric thermal expansion behaviour of ball-milled NiFe (81 wt.% of Ni) and NiFeMo (79 wt.% of Ni, 16 wt.% of Fe) alloy and follow its phase evolution when exposed to high pressure and temperature. In-situ pressure-temperature energy dispersive X-ray (EDXRD) diffraction experiments were performed at the MAX80 instrument (beamline F2.1). The compressibility of NiFe alloy at 400 °C was evaluated for pressure values of up to 3.5 GPa. The EDXRD spectra revealed the presence of cubic FeNi_{3} phase as determined from the shift of (111), (200) and (220) reflection lines in corresponding EDXRD spectra

Isobaric Thermal Expansion and Isothermal Compression of Powdered NiFe Based Alloys Studied by In-Situ EDXRD

The aim of the present work was to study the isothermal compression and isobaric thermal expansion behaviour of ball-milled NiFe (81 wt.% of Ni) and NiFeMo (79 wt.% of Ni, 16 wt.% of Fe) alloy and follow its phase evolution when exposed to high pressure and temperature. In-situ pressure-temperature energy dispersive X-ray (EDXRD) diffraction experiments were performed at the MAX80 instrument (beamline F2.1). The compressibility of NiFe alloy at 400 °C was evaluated for pressure values of up to 3.5 GPa. The EDXRD spectra revealed the presence of cubic FeNi_{3} phase as determined from the shift of (111), (200) and (220) reflection lines in corresponding EDXRD spectra

Magnetic Properties of Sintered Fe₅₀Co₅₀ Powder Cores

We investigated coercivity, total losses and complex permeability of sintered Fe-Co powder cores to detect magnetization processes performing in ac magnetic field. The Fe-Co solid solution alloy powders with 50:50 wt% ratio were prepared by 1, 15, and 20 h alloyed mixture of pure chemical elements in planetary ball mill. The resulting powder was subsequently sintered into a disk form. The compaction was performed at a pressure of 800 MPa for 5 min at temperatures of 400°C, 500°C and 600°C in vacuum oxidation protective atmosphere, with pressure of 5×10¯³ Pa. The best magnetic properties exhibit sample prepared from 1 h alloyed powder, compacted at 600°C

Influence of Milling and Compaction Processes οn Magnetic Properties of FeCo Powder

Magnetic and structural studies were performed on $Fe_{50}Co_{50}$ material. The samples (disk-shaped, diameter: 10 mm, thickness: 2.5 mm) were fabricated by compaction of powder under pressure of 800 MPa for 5 min at temperatures 300-600°C. The powder was obtained by milling of $Fe_{50}Co_{50}$ alloy swarfs in high-energy planetary mill. The milling time varied from 1 h to 40 h. In the course of milling process the mean size of alloy pieces was decreasing from about 0.5 mm to 0.05 mm (scanning electron microscopy), which provided more compact structure after compression. The annealing process during compaction strongly reduces a coercive field of the samples. Parameters of conversion electron Mössbauer spectra are almost the same for all samples, which points to not significant changes of atomic and magnetic order after milling and compacting