Increase in the coercivity of an ensemble of (DyPr)–(CoFe)–B microparticles during their dispersion in a polymer matrix

In ensembles of annealed ferrimagnetic alloy (DyPr)–(CoFe)–B microparticles in the free state and fixed in polymer, the coercivity differs more than by an order of magnitude. The contributions of orientation locking of magnetic axes of particles and the dipole magnetic interaction between particles to the coercivity and saturation magnetization field of an ensemble are discussed. In ensembles of unannealed microparticles, the effect of their locking and dispersing in polymer is significantly weaker.     

Effect of copper concentration on atomic site occupation by Fe ions and magnetic properties of (PrDy)–(FeCo)–B alloys

The effect of small copper additions (to ～6 at %) on the distribution of iron ions in six crystallographic sites of the unit cell of the main magnetic phase (PrDy)₂(FeCo)₁₄B has been detected. An increase in the copper concentration leads to a decrease in the 8j₁ site occupation by iron ions. Independently of the presence of copper, the temperature dependences of the saturation magnetization of all samples have a minimum which can correspond to the presence of a low-temperature phase or a compensation point in grain boundary regions of the (PrDy)₂(FeCo)₁₄B main magnetic phase. The alloys under study are not additive sets of all phases in their composition, but behave as new materials with the mutual influence of phases on each other.     

Magnetization Reversal of Ferromagnetic CoFeB Films and CoFeB/Ta/CoFeB Heterostructures in the Stray Field of Fe/Fe3O4 Nanoparticles

Journal of Experimental and Theoretical Physics - The magnetization reversal of the MgO/CoFeB/Ta/CoFeB/MgO/Ta/GaAs heterostructures and the ultrathin MgO/CoFeB/MgO/Ta/GaAs films with a...     

Distribution of slip tracks in single crystals of Ni3Fe alloy

The results of an experimental investigation of the distribution of slip tracks in a primary system in single crystals of Ni₃Fe alloy, oriented for a single slip, are presented. Investigations were carried out over a range of scales which differed by three orders of magnitude. Histograms of the distances between slip tracks at different scale levels are constructed. Self-similar track distributions in the primary slip system over the range of scales investigated are established. Tomsk State Architectural-Construction University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 51–56, April, 1998.     

Patterns of the Deformation Relief in Ni3fe Alloy Single Crystals with Long-Range Atomic Order

Russian Physics Journal - Patterns of evolution of plastic deformation macrofragmentation and localization in [1.8.12] Ni3Fe ordered alloy single crystals under compression are investigated. A...     

Magnetic properties of CoFeB alloys doped with Dy and Pr

Powders of the ferrimagnetic alloy CoFeBDyPr have been synthesized by the gas atomization method. Annealing of the samples at 900°C leads to the recrystallization of the amorphous phase into the crystalline phase (Pr,Dy)₂Fe₇Co₇B, which changes the magnetic properties of the alloy (the coercive force decreases, the shape of the magnetic hysteresis loop changes, etc.). The temperature dependences of the remanent magnetization and Mössbauer spectra depend on the size of particles. This indicates the contribution from subsurface magnetic states of the phase of different chemical composition, which is identified by X-ray photoelectron spectroscopy in particles with sizes of less than 10 μm. A weakening of the dipole-dipole interaction between particles in the sample, where they are diluted in the solid organic matrix (eicosane), leads to a change in the shape of the hysteresis loop. The elimination of the mechanical mobility of particles in eicosane significantly increases (to 2.5 times) the coercive force.     

Deformation-Induced Destruction of the Long-Range Order in Single Crystals of Ni3Fe Alloy

In the present work, x-ray diffraction and electron microscopy are used to investigate the state of a Ni₃Fe single crystal during plastic deformation. It is demonstrated that the observed destruction of long-range atomic order is accompanied with splitting of superdislocations and generation of single dislocations. The change of the long-range order parameter for single crystals deformed in the [001] direction estimated from the degree of splitting of superdislocations is in good agreement with x-ray measurements of this parameter. The destruction of long-range order for intermediate deformations < 40% is well described by the model of mechanical mixing of the alloy, the main role in which is played by the mechanisms of plane defect generation by shears along slip planes.     

Contributions of Magnetic Phases to the FORC Diagram in (NdDy)(FeCo)B Magnets

Physics of the Solid State - The relationship of the micromagnetic structure, the contributions of various crystalline phases and hysterons obtained by the first order reversal curves (FORC) method...