The temperature dependence of the magnetization of rapidly quenched amorphous Fe–Ni–Si–B alloys was studied by the magnetometry method. The Curie temperatures were determined, and the exchange interaction parameters was calculated: the constants of spin-wave stiffness and exchange stiffness, the root mean-square range of the exchange interaction. The nearest neighboring distance between transition metal atoms was estimated based on the magnetic characteristics.
X-ray diffraction analysis, ellipsometry, and optical microscopy have been used to study aluminum alloy samples (of Al and Al-2.3% V) fabricated by 3D printing using selective laser melting. The mechanical properties of the resultant products have been compared. The strength and plastic properties of parts made from pure Al and Al-2.3% V alloys have been found to be insensitive to heat treatment. The addition of vanadium to pure Al showed that the Al-2.3% V alloy has significantly improved performance properties compared to those of primary aluminum, without affecting its initial plasticity.
The surface of an AM60 (Al—5.5, Zn—0.2, Cu—0.009, Fe—0.005, Si—0.1, Ni —0.002, Mn—0.3 wt
The structural, electrical, and magnetic properties of lithium zinc ferrite prepared by ceramic technology have been studied. The composition of lithium zinc ferrite is Li0.4Fe2.4Zn0.2O4 with 1 and 2 wt % bismuth oxide. The addition of Bi2O3 prior to sintering of the samples has been shown to affect the structural, electrical, and magnetic properties of the ferrite. A significant increase in density from 4.47 to 4.65 g/cm(3) and a decrease in porosity from 4.8 to 2.3% have been observed when the concentration of bismuth oxide has been increased to 2 wt %. The Bi2O3-containing samples have higher specific electrical resistivity compared to that of the additive-free lithium zinc ferrite. The introduction of bismuth oxide has reduced the specific saturation magnetization from 70.55 to 54.76 G cm(3)/g. The Curie temperature has not changed significantly. An optimal combination of macroscopic properties of ferrite has been found at 1 wt % Bi2O3 concentration.
The electrical resistivity of 12Х18Н10Т stainless steel specimens was measured in the course of compression and heating under stepwise shock compression. A mathematical simulation of the obtained experimental data was conducted. The simulation allowed switching to specific values and reconstructing the volume–temperature dependence of the electrical resistivity of steel at high pressures of 25–65 GPa and temperatures of 350–950 K. Semi-empirical regularities were identified that permit the prediction of the total effect of a decrease in the electrical resistivity of 12Х18Н10Т steel upon compression and its increase upon heating. The outcomes of the electrical resistivity tests on shock-compressed and heated steel are evaluated in comparison with the existing literature data on similar experiments conducted under atmospheric pressure and high temperatures.
The process of precipitation of Al3Zr particles in cast Al–(0.25–0.4) wt
Based on the replica exchange algorithm of the Monte Carlo method, the influence of an external magnetic field on phase transitions and thermodynamic properties of the two-dimensional antiferromagnetic Potts model with the number of spin states q = 4 on a hexagonal lattice was studied. The studies were conducted in the range of external magnetic field values of 0.0 ≤ h ≤ 10.0. The magnetic field is measured in relative units of exchange interaction between nearest neighbors |J1|. The magnetic structures of the ground state were obtained, and the nature of phase transitions in the considered field range was analyzed. It has been established that in the intervals 0.0 ≤ h ≤ 3.0 and 6.0 ≤ h ≤ 6.5 a first-order phase transition is observed. It is shown that at the external magnetic field values h = 3.5 and 5.5, the system is frustrated, and in the magnetic field intervals 4.0 ≤ h ≤ 5.0 and 7.0 ≤ h ≤ 8.5, the system approaches the frustration regime. It was found that strong magnetic fields (h ≥ 9.0) suppress the phase transition in the system.
For a polycrystalline material with a hexagonal close-packed lattice, a model is proposed that allows estimating the yield strength at a given texture. The plasticity properties of an individual grain are described by the generalized von Mises criterion. The most widespread averaging approaches are considered to determine the yield strength of a polycrystal. An original averaging method for a heterogeneous medium under plastic deformation conditions is proposed that takes into account the presence of undeformed grains whose share is determined by means of the percolation theory. Using each approach, the problem about tension/compression of a homogeneous rod of square cross-section is solved for two limiting cases: no texture and rigid basis texture. The calculation results are juxtaposed with the available literature data. The effect of the texture on the yield strength is considered. A qualitative explanation of generating a texture is given.
