Vladimir E. Ovcharenko

Surface Modification of TiC–NiCrAl Hard Alloy by Pulsed Electron Beam

The mechanisms by which nanostructural states are realized in e-beam-irradiated TiC-NiCrAl cermet depending on the irradiation mode have been revealed. Mechanical testing and tribotesting have yielded criteria for a substantial (a factor of 1.5-3) increase in performance characteristics of the cermet alloy (micro- and nanohardness, cutting resistance, coefficient of friction, and bending resistance).

Improving Durability of Cermets for Metal Cutting by Generation of Subsurface Multilevel Structures

Experimental data on studying structural-phase states developed in the subsurface of TiC/Ni-Cr-Al alloy cermet under condition of superfast heating and cooling produced by pulse electron beam melting have been presented in this paper. The effect of the surface structural state multimodality on the temperature dependencies of friction and endurance of the cermet tool in cutting metal has been investigated. The effect of structural states on the cermet’s properties consists in improving its endurance for cutting metal by a factor of 20.

Modification of subsurface structure in TiC-(Ni-Cr) cermet composite under pulsed electron-beam irradiation of samples in plasmas of light and heavy inert gases

Experiments with metal ceramic alloys with various ceramic content proved that the performance degree of pulsed electron-ion-plasma irradiation as a technology of creating a surface layer multilevel structural phase condition, where particles are measured within a nano dimensional diapason, depends on ionization energy degree as well as on plasma-supporting gas atomic weight. When ionization energy falls parallel to plasma-supporting gas atomic weight growth, ceramic component particles dissolve in a metal binding melt more quickly, and an accelerated dispersion of ceramic particles to nano sized level can be observed. A multilevel structural phase condition causes friction ratio decrease, while a metal ceramic alloy surface layer wear ability increases many-folds.

Structural state scale-dependent physical characteristics and endurance of cermet composite for cutting metal

A structural-phase state developed on the surface of a TiC/Ni–Cr–Al cermet alloy under superfast heating and cooling produced by pulse electron beam melting has been presented. The effect of the surface’s structural state multimodality on the temperature dependencies of the friction and endurance of the cermet tool in cutting metal has been investigated. The high-energy flux treatment of subsurface layers by electron beam pulses in argon-containing gas discharge plasma serves to improve the endurance of metal cutting tools manifold (by a factor of 6), to reduce the friction via precipitation of secondary 200 nm carbides in binder interlayers. It is possible to improve the cermet tool endurance for cutting metal by a factor of 10–12 by irradiating the cermet in a reactive nitrogen-containing atmosphere with the ensuing precipitation of nanosize 50 nm AlN particles in the binder interlayers.

Bulk nanostructuring intermetallic composite material

The article states the results of a study of the impact rendered by the plastic strain occurring in a high-temperature synthesis product during the thermal explosion of a nickel-aluminum powder mixture on the grain structure, strength and ductility of the Ni3Al synthesized intermetallic compound.

The Structure and Properties of Hard Metals Irradiated by High-Energy Electron Beam

t has been established experimentally that irradiating the sample of tungsten carbide hard metal spray-coated by titanium layer 1-2 μm thickness by high-intensity electron beam resulted in generation of a gradient multi-phase nanostructured layer of microhardness higher than that of untreated material by a factor of 2.5.

Structural-Phase State and Strength Properties of Pressure-Synthesized Ni 3 Al Intermetallic Compound

The article studies dependences of grain size in Ni3Al intermetallic compound synthesized under pressure in 3Ni+Al powder mixture in conditions of bulk exothermal reaction upon pre-pressure acting on the powder mixture and upon a delay time of applying pressure to a high-temperature synthesis product. It is proved that an increase in the pre-pressure on the parent powder mixture reduces the grain size, and an increase in the delay time increases the grain size in the synthesized intermetallic compound. Reducing the grain size from 10 to 1.75μm increases the strength of the intermetallic compound under pressure from 336 to 482 MPa (1.4 times).

Study on TaC Reinforced Iron Matrix Surface Gradient Composites Produced In Situ

Tantalum carbide (TaC) gradient composites were fabricated via in-situ fabrication method from the tantalum plate and gray cast iron. The morphology, phase constituents, micro-hardness, and relative abrasion resistance of the composites were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-hardness tester and abrasive wear testing machine. The surface layer, which was ~160μm thick, was dense ceramic layer composed by ~90% submicron TaC particulates. The highest micro-hardness value of the dense ceramic layer was 13.84 GPa. In the sub-layer, the gradient distribution of TaC particulates reflected in the volume fraction decreased from 90% to 0%. While the micro-hardness value decreased from 10.81 GPa to 4.10 GPa. The metallurgical combination of the interface between the composites and matrix was perfect. The wear resistance of TaC reinforced iron matrix surface gradient composites increased significantly.

A General Process for In Situ Formation of Iron-Matrix Composites Reinforced by Carbide Ceramic

Ceramic particles (such as VC, NbC, TiC, and WC), which exhibit high hardness and thermal stability, can be used for in situ fabrication of carbide-reinforced iron matrix composites with high macro-hardness and toughness. In this study, we describe a novel in situ process comprising infiltration casting and heat treatment to form carbide-reinforced iron matrix composites with hard ceramic particles. Our proposed approach was used to integrate different alloy wires, which can easily form carbides, into the metal matrix and cast a known amount of carbon, such as gray cast iron, ductile cast iron, or ordinary white cast iron, to form alloy-reinforced iron matrix composites. Thermal treatment of the resulting composites allowed the alloy elements of the wire to react with carbon in the matrix to form evenly distributed carbide particles. This approach can be applied to a wide range of materials with different morphologies for fabricating composites, machining tools, and wear-resistant components.

Comparative analysis of different models of interphase boundaries in metal-ceramic composites

The paper is devoted to the comparative analysis of features of some popular mechanical models of interphase boundaries in metal-ceramic composite materials. We have numerically studied the influence of the parameters of interface models on effective strength, strain-hardening coefficient and ultimate strain of a microscopic composite fragment including adjacent areas of the matrix, inclusions and the interface zone. We have shown that the most “powerful” and flexible mechanical model of an interphase boundary is the model of an “interface shell” with a gradient of mechanical properties.