E. S. Savchenko

CHARGE SPECTRUM OF HEAVY AND SUPERHEAVY COMPONENTS OF GALACTIC COSMIC RAYS: RESULTS OF THE OLIMPIYA EXPERIMENT

The aim of the OLIMPIYA experiment is to search for and identify traces of heavy and superheavy nuclei of galactic cosmic rays (GCR) in olivine crystals from stony–iron meteorites serving as nuclear track detectors. The method is based on layer-by-layer grinding and etching of particle tracks in these crystals. Unlike the techniques of other authors, this annealing-free method uses two parameters: the etching rate along the track (V etch) and the total track length (L), to identify charge Z of a projectile. A series of irradiations with different swift heavy ions at the accelerator facilities of GSI (Darmstadt) and IMP (Lanzhou) were performed in order to determine and calibrate the dependence of projectile charge on V etch and L. To date, one of the most essential results of the experiment is the obtained charge spectrum of GCR nuclei within the range of Z > 40, based on about 11.6 thousand processed tracks. As the result of data processing, 384 nuclei with charges Z ≥ 75 have been identified, including 10 nuclei identified as actinides (90 < Z < 103). Three tracks were identified to be produced by nuclei with charges 113 < Z < 129. Such nuclei may be part of the Island of Stability of transfermium elements.

Effect of external actions on the magnetic properties and corrosion resistance of Co 70.5 Fe 0.5 Cr 4 Si 7 B 18 amorphous alloy

Variations in the magnetic characteristics (specific saturation magnetization and coercive force) of Co–Fe–Cr–Si–B amorphous alloy (AA) are studied after high-pressure torsion (HPT) and heat treatment. The behavior of AA magnetic properties is analyzed with respect to structural transformations caused by external actions. The corrosion resistance of AA upon transitioning from an amorphous to a crystalline state is investigated. The established optimum annealing and HPT conditions yield a satisfactory combination of the magnetic properties and corrosion resistance of the investigated alloy.

Effect of Magnetic Pulse Processing on the Structure and Magnetic Properties of Ferrites

The effect a pulsed magnetic field has on the crystal structure and macroscopic magnetic parameters of hexagonal ferrites BaFe12O19 and SrFe12O19 are studied. It is shown that changes in the physical properties of ferrites are due to the ordering of cation vacancies on the boundaries of hexagonal and spinel blocks that minimize local distortion of the oxygen polyhedrons. Violation of the collinear ordering of the magnetic moments of iron ions in the nonequivalent positions of SrFe12O19 ferrite is observed, due to the selective localization of such vacancies (and thus violations of the magnetic relationships in Fe–O–Fe).

Formation of High-Coercivity State in Fe2NiAl Alloy During Decomposition of Solid Solution Under Quenching from Liquid State and Subsequent Annealing

The methods of transmission electron microscopy, atomic force microscopy, x-ray diffraction, and magnetic measurements were used to study the laws of formation of the microstructure and magnetic properties in Fe2NiAl (alni) alloy after quenching from liquid state and subsequent annealing at 500 – 780°C. The microstructure of rapidly hardened flakes is characterized by the presence of inhomogeneities less than 10 nm in size and boundaries of anti-phase domains. Annealing of the flakes is accompanied by their discontinuous decomposition, which causes growth of the colonies comprising alternating plates of β′ andβ2′

Decomposition of the solid solution and the formation of a high-coercivity state in Fe2NiAl alloy upon cooling at the critical rate

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The Effect of the Rate of Cooling from High-Temperature Single-Phase Region on the Microstructure and Magnetic Properties of AlNi Alloys

phases on grain boundaries.

Peculiarities of the spinodal decomposition and magnetic properties in melt-spun Fe2NiAl alloy during aging

The systematic investigation of changes in the phase composition and magnetic properties is carried out for amorphous melt spun Fe83B17 alloy after annealing at 450°C for 1 h and for microcrystalline single roll melt Fe75B25 alloy after annealing at 530°C for 1–18 h.

Evolution of the microstructure and magnetic properties of as-cast and melt spun Fe2NiAl alloy during aging

Transmission electron microscopy and magnetic measurements are used to study the formation of the microstructure and magnetic properties of Fe2NiAl (alni) alloy upon cooling at the critical rate (V ∼ 2°/min) from the region of single-phase solid solution (1240°C). Cooling is interrupted by water quenching caused by temperatures Тquench. The periodical modulated structure formed during sample cooling at the critical rate guarantees the strongest possible coercive force (Нс = 670 Oe). The decomposition of the solid solution below 900°C includes a stage of primary modulated structural failure upon continuous cooling to temperature Тquench ∼ 850°C, which corresponds to the weakest coercive force on the Нс(Тquench) curve. The periodical modulated structure is recovered when the temperature falls further; this is accompanied by an increase in the coercive force (up to Нс = 670 Oe) after cooling to 20°C.