A numerical Monte Carlo study of the nonequilibrium behavior of multilayer magnetic superstructures consisting of alternating magnetic and nonmagnetic nanolayers is performed. The calculated two-time ...autocorrelation function and the staggered magnetization of the structure at its evolution starting from various initial states are analyzed. The analysis reveals aging effects characterized by a slowing down of the relaxation and correlation characteristics in the system with the waiting time. It is shown that, in contrast to bulk magnetic systems, the aging effects in magnetic superstructures arise not only near the ferromagnetic ordering temperature
T
c
in the films but also within a wide temperature range at
T
≤
T
c
.
The results of the influence of thermocyclic forging and annealing in the range of 100 ÷ 900 °C on the microstructure, coercive force and linear expansion of steel 10. Hot cyclic forging was carried ...out on slabs 900×700×500 mm in size on the hydraulic press with a force of 20 MN under industrial conditions of ZSMK OJSC (Novokuznetsk). Subsequently, the billets were rolled on a 3 mm thick sheet at OAO NMZ (Novosibirsk). The use of preliminary thermocyclic deformation increases the coercive force by no more than 8%. The possibility of reducing the coercive force of sheet steel made using thermocyclic forging was shown to be almost 3 times lower than the initial untreated state due to subsequent annealing at 900 °C for 10 hours. In addition, this annealing mode reduces the average linear expansion temperature coefficient of sheet steel by 6% in the temperature range of the test 50-450 °C.
The Monte Carlo simulation of the critical behavior of multilayer structures based on anisotropic Heisenberg mode are presented. The non-equilibrium critical relaxation of structures consisting of ...two magnetic layers with dipolar interlayer interaction is studied. The investigation of non-eqilibrium critical behavior of multilayer structure wich correspond to the nanoscale superlattice Co/Cr demonstrates that the aging effects can be observed in a wider temperature range than for bulk magnetic systems.
Al – 11% Si hypoeutectic alloy and Al – 20% Si hypereutectic alloy are studied after two-stage modification of the surface, which combines electroerosion alloying and subsequent irradiation with a ...pulsed electron beam. The structure of the surface layer is determined after two variants of two-stage treatment. The two-stage treatment of alloy Al – 11% Si yields a multi-element multiphase layer with a thickness of about 80 μm and a submicro-nanocrystalline structure. The surface of alloy Al – 20% Si acquires two layers (a surface one and an intermediate one) differing in the structure from the silumin. The surface layer contains many phases and is up to 1 μm thick. The transition layer with a thickness of up to 40 μm is formed from rapid-crystallization cells produced by the high-rate cooling of the fused layer of alloy Al – 20% Si. The cells are separated by thin sublayers composed of chiefly silicon nanosize particles.
The lifetime of the neutron is one of the key physical quantities used to determine the weak interaction parameters and to test predictions of the theory of primary nucleosynthesis. The lifetime of ...the neutron has been measured in the reported experiment by the method of storing neutrons in a material trap with a gravitational valve. Fomblin grease UT-18 hydrogen-free fluorine polymer has been used as coating. The resistance of the coating to repeated cooling down to 80 K combined with heating up to 300 K has been studied. The probability of losses in the trap is as small as 1.5% of the neutron decay probability. The lifetime of the neutron τ
n
= (881.5 ± 0.7
stat
± 0.6
syst
)s obtained at the new step is in good agreement with a commonly accepted value of (880.2 ± 1.0) s presented by the Particle Data Group.
A series of piston hypereutectic silumins based on Al - (15 ÷ 20) % Si alloyed with copper, magnesium, nickel, and chromium was studied. The alloys were modified with phosphorus and ...hydrogen-containing reagents to increase the deformability and mechanical properties. The experimental ingots, cast in the steel mold, had dimensions: diameter 190 mm, height 500-550 mm, weight 32-40 kg. The mechanical properties and temperature coefficient of linear expansion (TCLE) of the experimental ingots and forgings made from them are determined. Temporary tensile strength and relative elongation of deformed ingots from hypereutectic silumins were 227-306 MPa and 5.7-7.5%, respectively. The optimal heat treatment of deformed silumins was determined: quenching with step heating and aging, which allows the strength of forgings to be increased up to 370-470 MPa. Moreover, the ductility indicators remain at a high level, and the average TCLE of the alloys is (18.0 ÷ 19.2) ·10−6 К−1 in the range of 50 ÷ 200 °C.
The effect of melt hydrogen treatment on structure, morphology, and on physical and mechanical properties of hypereutectic alloy Al – 15% Si in cast and deformed conditions is studied. A melt is ...treated with hydrogen by different methods, i.e., with wet asbestos, in a steam atmosphere, and flushing with hydrogen prepared by alkali decomposition with aluminum. Ingots are deformed plastically by open forging and rolling. Alloy microstructure is studied by metallographic, electron microscopic, x-ray diffraction, and dilatometric analyses. Alloy density and microhardness are measured. Alloy atomic hydrogen content is studied by vacuum heating. It is shown that hydrogen treatment improves cast alloy structural parameters and deformability, raises post-deformation strength by a factor of 1.3 – 1.4, and lowers linear expansion coefficient.
In this paper, a new "single-wall" scheme of a high-speed wingless jet aircraft without compressor, which has the smallest, practically "zeroed" external friction and heat and mass transfer ...resistance with an active external near-wall boundary layer and tangential injection of the superheated steam from a cooling jacket SCC walls was proposed. Moreover, due to the limited flow rate of the combustible laminar sublayer vapor injection and the laminar "scaly" sublayer zeroed friction, the average Mach number of the vortex external near-wall boundary layer will be only 2% less than the Mach number of the flight speed. This circumstance allows not to merge the frontier layer of the hull ("fuselage"), as is done on the overwhelming majority of the aircrafts, but to use the energy and mass of the near-wall boundary layer as a normal incoming air flow.
The article describes the welding process study with the subsequent control of cooling for full-profile rail joints, produced by passing alternating electric current pulses after welding. The welding ...mode influence on the welded joint quality was investigated. Welding was carried out on a resistance butt welding machine MCP-6301 in conditions of the rail welding company OOO RSP-M (RSP-29). For research, the samples of P65 type full-profile rails of DT350 category 600 mm long were cut out. The isothermal holding conditions after welding were controlled using a personal computer with a change in the program of the SIMATIC S7-300 industrial controller and the software SIMATIC STEP 7, which allows modes of controlled cooling to be set. The control program was written in the LAD graphic language. To search for optimal modes of controlled cooling, a complete factor experiment
N
= 2
k
was carried out. Non-heat-treated joints were tested for three-point static bending according to the state standard STO RZD 1.08.002 – 2009 “Railway rails, welded by electric contact method”. Static bending tests were carried out on the press of PMS-320 type. Values of the force arising during bending
P
bend
and the bending deflection
f
def
at which the control sample is destroyed, were determined. The maximum values of these indicators were also determined if the sample was not destroyed during the tests. During the experiments, regression models were obtained for output parameters of the bending force and bending deflection. Sample macrostructure and metal hardness distribution on rolling surface of the rails welded joint were studied. A new method of resistance butt welding was developed, which makes it possible to obtain a welded connection of P65 type rails of DT350 category with properties that exceed the technical requirements of the mentioned state standard.
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