Yu. K. Kovneristyi

Permeability, diffusion, and solubility of hydrogen in Cr−Ni and Cr−Mn austenitic steels

Conclusions1.Alloying of Cr−Mn and Cr−Ni austenitic steels has almost no effect on the kinetic coefficients of the interactions with hydrogen.2.Oxidation of Cr−Mn and Cr−Ni austenitic steels leads to a substantial reduction of hydrogen permeation at temperatures below 600° in comparison with unoxidized steels. At temperatures above 600° the hydrogen permeation of oxidized and unoxidized steels is practically the same, which is due to the instability of oxides under the influence of hydrogen, high vacuum, and high temperature.

Nanocrystalline Fe-P-Si alloys

Annealing Fe-P-Si amorphous alloys was found to produce nanocrystalline particles and raise the microhardness of the alloys by a factor of 2 to 3. The most significant strengthening was observed in the alloys containing the smallest amounts of Si and P and the largest amount of the α-Fe-based phase. As shown by x-ray diffraction and electron microscopy, the alloy consisting entirely of nanocrystalline phases with a particle size of about 25 nm crystallizes in three steps.

Mössbauer Study of Nanoscale Crystallization in Amorphous Fe–P–Si Alloys during Annealing

The crystallization behavior of amorphous Fe–P–Si alloys is studied by Mössbauer spectroscopy and physicochemical analysis. The resulting materials are found to contain nanocrystalline particles of complex composition, characterized by a doublet and several sextets in the Mössbauer spectrum. In the alloys containing 6 or 10 at. % Si, crystallization leads to the precipitation of pure Fe, which increases Si mobility and, accordingly, the rate of particle growth.

Physicochemical Properties of Amorphous and Crystalline Fe–P–Mn and Fe–P–Mn–V Alloys

Annealing Fe–P–Mn and Fe–P–Mn–V soft-magnetic amorphous alloys prepared from ferrophosphorus waste leads to the formation of fine-particle crystalline phases. The associated structural hardening is more pronounced in alloys with stronger interatomic interactions. The dissolution of Mn and V inhibits the growth of Fe3P particles, which become smaller than the α-Fe particles.

Fe-P-M (M = Si, Mn, V) alloys: Viscosity in the liquid state and tendency to amorphization

The viscosity of Fe-P-M (M = Si, Mn, V) melts was measured. The effects of the alloying elements on melt viscosity and the tendency of the alloys to amorphize were shown to increase in the order Si → Mn → V. By combining alloying elements, amorphous alloys were prepared which crystallize in three and four steps, yielding multiphase materials.

Formation of a nanocrystalline structure in an iron-base amorphous alloy under the influence of a pulsed magnetic field

Processing the amorphous Fe77P13Si5Mn2.4V0.2C2.4 alloy with one or four 1-ms magnetic pulses of energyE = 1, 5, or 7 kJ was found to reduce the size of coherently scattering domains and notably raise the strength of the alloy, especially atE = 5 kJ. Mössbauer spectroscopy and x-ray diffraction data demonstrate that annealing at 773 K for 10 min and pulsed magnetic processing withE = 5 kJ give rise to the formation of a large number of nanocrystalline phases containing Fe atoms in various states.

Nanoscale crystallization in the amorphous alloy Fe79P14.2Si4.4Mn2.2V0.2 upon pulsed photon annealing

The effect of pulsed photon annealing with energy densities from 1.4 to 42 J/cm2 for various lengths of time on the structure of the amorphous alloy Fe79P14.2Si4.4Mn2.2V0.2 was studied by x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The results demonstrate that short-term irradiation with low energy densities leads to surface relaxation of the amorphous alloy, increases the strength of the surface layer, and reduces the internal-friction peak. Longer term photon annealing leads to crystallization of the alloy throughout the sample thickness.

Nanoscale Crystallization in Amorphous Fe–P–Mn Alloys

Mössbauer effect measurements and physicochemical analysis demonstrate that annealing of amorphous Fe–P–Mn alloys leads to the formation of a nanocrystalline structure.

Amorphization behavior and nanocrystalline structure of Fe-P-Si-V alloys

It is found that Fe–P–Si–V alloys tend to be in an amorphous state on cooling at a rate of 105to 106K/s. As compared to Fe–P–Si alloys, the crystallization behavior of the Fe–P–Si–V alloys is more complex owing to the formation of both metastable and equilibrium silicides. The metastable phases are nanocrystalline, as evidenced by transmission electron microscopy, which ensures a noticeable strength gain.

Nanocrystals in Fe–P–Si–Mn Alloys

Annealing Fe–P–Si–Mn amorphous alloys is found to produce a few nanocrystalline phases, with a strength gain no higher than that in Fe–P–Si alloys. This crystallization behavior is accounted for by the formation of two metastable silicides whose growth rates during annealing are higher than those of the equilibrium phases.