It is shown that at low temperatures, quantum oscillations of nanoscale structural inhomogeneities (the vertical Bloch line and the Bloch point) occur in the domain walls of cylindrical magnetic domains formed in a uniaxial magnetic film with strong magnetic anisotropy. The conditions for the excitation of these oscillations are determined.
Quantum effects such as tunneling through pinning barrier of the Bloch Point and over-barrier reflection from the defect potential of one have been investigated in ferromagnets with uniaxial strong magnetic anisotropy. It is found that these phenomena can be appeared only in subhelium temperature range.
We have studied the structure and mechanical properties of eutectic alloys β-NiAl + γ-Re of the ternary system Ni − Al − Re. We have established that the best combination of mechanical characteristics, determined by local loading with a rigid indentor, is exhibited by the alloy containing 2.5 at.% Re, the structure of which consists of the eutectic β-NiAl + γ-Re. Rhenium inclusions can inhibit movement of cracks in the material, and also can play the role of traps for cracks. Brittle intercrystallite fracture is characteristic of the alloy consisting of one-phase intermetallic NiAl. Mixed fracture is typical of the eutectic alloy β-NiAl + γ-Re, with transcrystallite cleavage predominating. We have shown that plastic interlayers of a rhenium phase within the microstructure increase the crack resistance of a detonation coating made from eutectic alloys β-NiAl + γ-Re.Nickel aluminide NiAl, having (along with high scaling resistance (up to 1400°C)) a density 1.35 times lower and a thermal conductivity 4 times higher than nickel superalloys, is a promising compound to use as a basis for developing new structural materials and protective coatings for gas turbine engines for aviation [1][2][3]. Major factor holding back widespread use of materials based on nickel aluminide is lack of plasticity at room temperature and low crack resistance.Progress in improvement of the class of materials under consideration is mainly connected with development of the optimal composite structure by introducing alloying components into their composition: Cr, Mo, Nb, V, Ti, Ta, etc.[4-6]. One such promising component is rhenium, which as we know [9-11] has an unusual combination of unique characteristics: high modulus of elasticity, high recrystallization temperature, high fatigue strength. From experience using rhenium in superalloys, we know [3,4] that introducing rhenium into a material may simultaneously increase both the strength and the plasticity. Moreover, rhenium makes it possible to form eutectic structures that often have more fortunate combination of characteristics, compared with other structural composites. A slight amount of rhenium is contained in an NiAl solid solution (0.2 at.%) [9].Our previous investigations [11] allowed us to determine the limits of the region of existence for eutectic alloys β-NiAl + γ-Re that are two-phase in crystallization. From this region, we have selected alloys containing from 0.2 to 3.0 at.% rhenium in order to assess the mechanical properties of β-NiAl + γ-Re eutectic alloys and coatings sprayed from powders, obtained from the ingots by mechanical crushing.
EXPERIMENTAL SECTIONThe alloys were melted in an electric arc furnace with a nonconsumable tungsten electrode on a water-cooled copper hearth in a purified argon atmosphere. The elemental distribution in the structure was determined using a Camebax SX-50 electron probe microanalyzer (France). In order to assess the mechanical properties of the materials, we used the method of local loading by a rigid indentor [9], including plotting of the...
On the basis of the method of gyrotropic Thiele forces, we build a formalism that allows the determination of the effective mass of the nanoscales structural elements of the domain wall (DW): vertical Bloch line and Bloch point in uniaxial ferromagnets. As shown, the effective mass of these magnetic inhomogeneities depends on the value of the gyrotropic domain wall bend that is created by their movement.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-0861-z) contains supplementary material, which is available to authorized users.
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