A. N. Tabachenko

Causes of differences in diffusion coefficients determined by rotating-disk method (nickel-aluminum system)

The authors discuss the applicability of various computational formulas to the determination of diffusion coefficients by the rotating-disk method. The aluminum-nickel system is used as an example for studying the effect of impurities in the materials investigated on the equilibrium solubility and the transfer coefficients in liquid solutions. The viscosity and diffusion coefficients are measured at 700–1250°C.

Intrusion features of a high-speed striker of a porous tungsten-based alloy with a strengthening filler in a steel barrier

The complex problem of increasing the penetrating power of strikers based on highly porous tungsten composites is considered by improving their strengthening properties by alloying the hardening components under high-speed collision conditions. Using the method of liquid-phase sintering, we fabricated samples of strikers based on a porous WNiFeCo alloy (tungsten + nickel + iron + cobalt), alloyed with tungsten carbide with cobalt (WCCo8) and titanium-tungsten carbide (TiWC). Dynamic tests of the strikers from the developed alloys were carried out at the collision velocity with a steel barrier of the order of 2800 m/s. The penetration depth of the striker based on a porous WNiFeCo alloy doped with tungsten carbides is 30% higher than the penetration depth of a striker of a monolithic WNiFe-90 alloy (tungsten + nickel + iron with a tungsten content of 90%).

Spall destruction of coarse-grained and ultrafine-grained titanium on exposure to nanosecond heavy-current electron beam

This paper presents results of experimental and theoretical research of spall destruction of volume coarse-grained and ultrafine-grained titanium when using it as a generator of shock wave of nanosecond relativistic heavy-current electron beam. Computer modeling of effect of an intensive electron beam on the condensed target has been carried out taking into account destruction, phase transitions, dependence of strength characteristics of materials on internal energy. This is considered within elastic, ideally plastic Prandtl-Reiss model. The results of calculations are compared with experimental data.

Design of nanostructured cermet materials high-speed impact conditions

The means of production of nanostructured composite materials by the method of self-propagating high-temperature synthesis (SHS) with the application of pressure to the product of combustion and by the method of intensive plastic three-sided a,b,c deformation are considered. A composite material of combined structure is developed, which is a layer system, one of the layers of which is a product of the exothermic reaction of the Ti-B-Ni system in the form of an interlayer produced by pressing the heated SHS product, and the other layer is inert, the role of which is played by the metal layer. The properties of the developed materials, including the TiB2 + B4C-based ceramic metal, are studied under the conditions of high-speed impact.

Mathematical Modeling of Deformation and Fracture of Cermets under Dynamic Loading Conditions

The behavior of cermets under shock-wave loading conditions is examined. The materials under study are produced by self-propagating high-temperature synthesis. A mathematical model for calculating the stress-strain state and fracture of the TiB + B4C-based cermet is developed.

Synthesis of Two-Layer Metal–Ceramic Materials with High-Velocity-Impact Resistance Based on Refractory Compounds and Titanium

We consider the possibility of obtaining composites with increased mechanical strength resistant to high-velocity impact by means of self-propagating high-temperature synthesis (SHS) of metal–ceramic materials with graded composition–in particular, of layered type. A two-layer combined metal–ceramic material has been developed comprising NiTi-bonded titanium diboride (TiB2) layer on a metallic titanium substrate layer. The impact resistance of this composite is advantageous to that of a homogeneous titanium plate, which is manifested by the absence of a spall crater upon the impact of a spherical steel projectile and by stronger deformation and prefracture cracking of the projectile.

Development and Investigation of a Two-Layer Metal—Ceramic Material for Protective Barriers in Conditions of High-Speed Impact

The possibility of improving the physico-mechanical characteristics of composite materials used in protective structures against a high-speed impact is considered. By means of self-propagating high-temperature synthesis, a two-layer cermet is obtained: the front layer is a cermet based on titanium diboride with a titanium nickelide bond, and the back layer is a titanium alloy. The study by the computational-experimental method of the impact resistance of this composite in comparison with a homogeneous titanium plate showed a qualitative advantage expressed in the absence of a shock crater in a cermet plate after a collision with a steel spherical impactor and stronger deformation and prefracture of the impactor. The two-layer cermet has a high resistance to the penetration of the steel impactor.

Features of the destruction of homogeneous and composite barriers during high-speed interactions with rod impactors

The destruction of homogeneous and composite barriers with metal-ceramic intermediate layers that interact with WNiFe-90 alloy impactors has been investigated. A comparison of the results for different types of barriers was provided based on the weight equivalence, i.e., the equality of weight per unit barrier area along the thickness. The initial impact velocity was in the range of 0.8–1.1 km/s. The registration of the process from the moment of strike of impactor to the formation of the developed fragmentation flow behind the barrier was carried out by a high-speed video camera. The displacement–time dependences for the characteristic planes of the target configuration, i.e., the rear end of the impactor and the rear surface of the barrier were plotted by processing video film. An analysis of these dependences allowed us to identify the features of barrier destruction. The strong difference in the geometry of the zones of destruction and the dynamics of the process for monolithic and composite barriers has been noted.

Differences in the Properties of Ti–C–Mo–S Antifrictional Coatings on 40Kh and 20Kh13 Steel

The tribological and physical properties of Ti–C–Mo–S antifrictional coatings applied by a hybrid magnetron–plasma method on 40Kh and 20Kh13 steel substrates are compared. The coatings on the 40Kh and 20Kh13 steel substrates are applied in precisely the same conditions by magnetron sputtering of cathodes produced by self-propagating high temperature synthesis (SHS), with the assistance of high-density gas-discharge plasma formed by a PINK plasma source. The methods used in coating application are detailed. The coated substrates undergo frictional tests in a pin-on-disk configuration. The relative velocity of the counterbodies is 50–60 cm/s. The results show that the tribological characteristics of the coating—in particular, the wear resistance—depend significantly on the substrate. The coating life is significantly different on different substrates: specifically, the wear resistance is higher for the coating on low-carbon (about 1%) 40Kh steel than on high-chromium (about 13%) 20Kh13 steel. Optical and scanning electron microscopy of the wear tracks reveals qualitative and quantitative differences in the coating wear on 40Kh and 20Kh13 steel substrates. By means of an electronic profilometer, the coating wear in 1000 disk cycles may be assessed on the basis of the mean cross-sectional area of the wear track, which is four times greater for the 20Kh13 steel substrate. Analysis of the tribological and physical properties indicates that the difference in the properties is due primarily to the different initial chemical and phase composition and the structural differences of the substrates, which determine the properties of the alloyed surface layer and the adhesive strength of the coating to the substrate and ultimately determine the wear mechanism.

Prediction of the consequences of a high-velocity collision between meteoric particles and elements of a titanium alloy protective structure

Calculation-experimental studies of a high-velocity collision between VT1-0 titanium plates and ultrafine- and coarse-grained structures with a steel spherical impactor are illustrated. Fine-grained VT1-0 titanium plate samples have been obtained using the abc pressing method. Ballistic measurements have been performed using a 30-mm smooth-bore ballistic installation at velocities of about 2500 m/s. A high-velocity collision has been calculated in the scope of an elastoplastic model of interacting materials with regard to destruction and a different phase state at velocities reaching 15 km/s. It has been indicated that the mechanical properties of the VT1-0 alloy are improved when proceeding from a coarse-grained structure to an ultrafine- grained structure; however, in this case, the result of shock loading is hardly affected in the considered velocity range. Titanium plates can be used as screens to protect the main structure of the aircraft from a high-velocity collision.