Intense Pulsed Electron Beam Research Articles

Structural phase states and properties of the layer surfaced on low-carbon steel with Fe‒C‒Cr‒Nb‒W powder-core wire followed by electron-beam processing

Structural phase states and tribological properties of the coating surfaced onto Hardox 450 martensite low-carbon steel with powder wire Fe‒C‒Cr‒Nb‒W and modified by subsequent electron-beam processing are studied by methods of modern physical material science. It is shown that irradiation of ~5 thick surfaced layer with high intensity pulsed electron beams results in the formation of ~20 μm thick surface layer with the master phases of α-Fe and NbC, Fe3C and M6C(Fe3W3C) carbides. The main difference of the surface layer modified with electron-beam processing from the unmodified volume of the surfacing is the morphology and dimensions of the second phase inclusions. In the modified layer of the surfacing the inclusions have smaller dimensions and are located in the form of interlayers along the grain boundaries. In unmodified surfacing the particles of the faceted shape located chaotically in the grain volume are the basic morphological type of the inclusions. It is noted that the small value of crystal lattice Nb parameter observed in the experiment may be caused by the high level of vacant interstitial sites having the smaller size in comparison with the occupied interstitial sites. It is established that wear resistance of the surfaced layer after electron-beam processing increases more than 70-fold relative to wear resistance of Hardox 450 steel and friction coefficient decreases significantly (~3-fold).

Mechanical Properties and Structure of the Hypereutectic Silumin Treated by an Electron Beam

Treatment of hypereutectic structure silumin (18-24 wt% of Si) by an intense pulsed electron beam of submillisecond duration is carried out. Formation of submicro- and nanocrystalline structure in the surface layer is revealed, which is caused by ultrahigh (up to 108 K/s) cooling rates of the melted layer. It is established that the modification of the silumin surface layer by an electron beam increases its hardness by 5 times.

Numerical and experimental characterization of a plasma induced on a solid target by an intense pulsed multi-MeV e-beam

We investigate the interaction of an intense pulsed multi MeV electron beam with a solid target on the ASTERIX high voltage generator using a set of numerical and experimental tools. Physical mechanisms occurring at various stages are examined, from electron beam dynamics to X-ray production, including plasma generation at the solid target surface. First, the electron beam characteristics are determined using 2D axisymmetric Particle-In-Cell calculations and a good agreement is found between calculated and measured current and voltage profiles. Calculated electron beam characteristics serve as an input to a 3D Monte-Carlo code in order to simulate the dose distribution within the solid target. The plasma produced at the target surface upon interaction with the electron beam is diagnosed and quantitatively characterized through UV-visible emission spectroscopy. Plasma species are identified and spectroscopy data are analyzed based on a 1D radiative transfer model, allowing electron density and temperature profiles to be inferred. Such combined numerical and experimental investigation is promising for gaining insight into physical mechanisms occurring upon the interaction between high energy electrons and solid targets.

Study of linearity of LYSO crystal for the high energy cosmic radiation detection (HERD) facility

The high energy cosmic-radiation detection (HERD) facility is a space mission designed for detecting cosmic ray (CR) electrons, $$\gamma $$ -rays up to tens of TeV and CR nuclei from proton to iron up to several PeV. The main instrument of HERD is a 3-D imaging calorimeter (CALO) composed of nearly ten thousand lutetium yttrium orthosilicate (LYSO, with cerium doping) crystal cubes. A large dynamic range of single HERD CALO Cell (HCC) is necessary to achieve HERD’s PeV observation objectives, which means that the response of HCC should maintain a good linearity from minimum ionizing particle (MIP) calibration to PeV shower maximum. In order to study the linearity of HCC over such a large energy range, a beam test has been implemented at the E2 and E3 beam lines of BEPC. High intensity pulsed electron beam provided by E2 line is used for producing high energy density within HCC; $$\pi ^{+}$$ /proton provided by E3 line are used for HCC calibration. The results show that no saturation effect occurs and the linearity of HCC is better than 10% from 30 MeV (1 MIP) to $$1.1\times 10^{3}$$ TeV (energy density is 93 TeV/cm $$^{3})$$ , which can meet the requirement mentioned above.

Texture formation in the surface layer of VT6 alloy targets irradiated by intense pulsed electron beams

The texture formed in the surface layer of a recrystallized VT6 titanium alloy irradiated by highcurrent pulsed electron beams (HEBs) in a melting mode is studied. It was ascertained that irradiation in the melting mode leads to the formation of compression texture and fine globular-lamellar structure in the surface layer with thickness of 20 μm with preferred orientation of α, α′, and α″ lamellae parallel or nearly parallel to the surface. Structural changes observed in the surface layer are the cause of improvement of fatigue strength of titanium alloy induced by HEB treatment.

Nanohardness of wear-resistant surfaces after electron-beam treatment

The nanohardness, Young’s modulus, and defect substructure of the metal layer applied to Hardox 450 low-carbon martensitic steel by high-carbon powder wire (diameter 1.6 mm) of different chemical composition (containing elements such as vanadium, chromium, niobium, tungsten, manganese, silicon, nickel, and boron) and then twice irradiated by a pulsed electron beam are studied, so as to determine the correct choice of wear-resistant coatings for specific operating conditions and subsequent electron-beam treatment. The metal layer is applied to the steel surface in protective gas containing 98% Ar and 2% CO2, with a welding current of 250–300 A and an arc voltage of 30–35 V. The applied metal is modified by the application of an intense electron beam, which induces melting and rapid solidification. The load on the indenter is 50 mN. The nanohardness and Young’s modulus are determined at 30 arbitrarily selected points of the modified surface. The defect structure of the applied metal surface after electron-beam treatment is studied by means of a scanning electron microscope. The nanohardness and Young’s modulus of the applied metal after electron-beam treatment markedly exceed those of the base. The increase is greatest when using powder wire that contains 4.5% B. A system of microcracks is formed at the surface of the layer applied by means of powder wire that contains 4.5% B and then subjected to an intense pulsed electron beam. No microcracks are observed at the surface of layers applied by means of boron-free powder wire after intense pulsed electron-beam treatment. The boron present increases the brittleness. The increase in strength of the applied layer after electron-beam treatment is due to the formation of a structure in which the crystallites (in the size range from tenths of a micron to a few microns) contain inclusions of secondary phases (borides, carbides, carboborides). The considerable spread observed in the nanohardness and Young’s modulus is evidently due to the nonuniform distribution of strengthening phases.

СТРУКТУРА И СВОЙСТВА ПОВЕРХНОСТИ НАПЛАВКИ, ОБЛУЧЕННОЙ ИНТЕНСИВНЫМ НИЗКОЭНЕРГЕТИЧЕСКИМ ИМПУЛЬСНЫМ ЭЛЕКТРОННЫМ ПУЧКОМ

To substantiate the selection of a coatings material conforming to the operating conditions of the products and the subsequent electron-beam processing conditions, the authors studied the microhardness, Young’s modulus and the microstructure of modified surface layer deposited on the martensitic low-carbon Hardox 450 steel with the high-carbon powder wires of various chemical composition (No. 258 (NbC-G), No. 720 (DT-DUR), No. 760 (DT-DUR)) and further modified by the irradiation with the intense pulsed electron beam using the two-step method. The formation of fused layer on steel surface was carried out in the shielding gas environment containing 98 % Ar, 2 % CO 2 , with the welding current of 250–300 A and the arc voltage of 30–35 V. The modifying of a fusion layer was carried out by irradiating the fusion layer surface with a high-intensity electron beam in the mode of melting and high-speed crystallization. The load on the indenter was 50 mN. The Young’s modulus microhardness was determined in 30 arbitrarily selected points of the modified surfacing surface. The structure of modified by electron beam surfacing surface was studied with the scanning electron microscopy methods. It is determined that the increase in strength properties of the modified by the electron beam weld layer is caused by the formation of a sub-microsized structure, the hardening of which is caused by the quenching effect and the presence of the second phase inclusions (borides, carboborides, carbides). It was found that the maximum hardening effect is observed when surfacing with a flux-cored wire containing 4.5 % of boron. The study shows that the microcracks systems are formed on the surfacing surface formed by a wire, the elemental composition of which includes 4.5 % of boron, and additionally irradiated with the intense pulsed electron beam. While the surface surfacing formed by the powdered wires free of boron after the pulsed electron beam treatment demonstrated the absence of microcracks on the modified surface. The authors determined the significant spread in nanohardness and Young’s modulus values that was apparently conditioned by the nonuniform distribution of strengthening phases.

Comprehensive surface treatment of high-speed steel tool

One of the promising directions of hardening of high-speed steel tool is the creation on their surface of the layered structures with the gradient of physic-chemical properties between the wear-resistant coatings to the base material. Among the methods of such surface modification, a special process takes place based on the use of pulsed high-intensity charged particle beams. The high speed of heating and cooling allows structural-phase transformations in the surface layer, which cannot be realized in a stationary mode. The treatment was conducted in a RITM-SP unit, which constitutes a combination of a source of low-energy high-current electron beams “RITM” and two magnetron spraying systems on a single vacuum chamber. The unit enables deposition of films on the surface of the desired product and subsequent liquid-phase mixing of materials of the film and the substrate by an intense pulse electron beam. The article discusses features of the structure of the subsurface layer of high-speed steel M2, modified by surface alloying of a low-energy high-current electron beam, and its effect on the wear resistance of the tool when dry cutting hard to machine Nickel alloy. A significant decrease of intensity of wear of high-speed steel with combined treatment happens due to the displacement of the zone of wear and decrease the radius of rounding of the cutting edge because of changes in conditions of interaction with the material being treated.

SURFACE NANOHARDNESS OF WEAR RESISTANT SURFACING IRRADIATED BY ELECTRON BEAM

The nanohardness, Young elastic modulus and defect substructure of the layer surfaced on the low carbon martensite Hardox 450 steel by the high carbon power wires with diameter of 1.6 mm of different chemical composition (containing such elements as V, Cr, Nb, W, Mn, Si, Ni, B) and two times additionally irradiated by the pulse electron beam were studied for the purpose of substantiated selection of coating material corresponding to the product operation conditions and the modes of subsequent electron beam treatment. The formation of the fused layer on the steel surface was carried out in the shielding gas medium containing 98 % Ar, 2 % CO 2 , with a welding current of 250 – 300 A and a voltage on the arc of 30 – 35 V. Modification of the deposited layer was carried out by irradiating the surface of the deposited layer by a high-intensity electron beam in the mode of melting and high-speed crystallization. The load on the inductor was 50 mN. Determination of the nanohardness and Young elastic modulus was carried out at 30 arbitrarily chosen points of the modified surface. The defect structure of the surface modified by of an electron beam of the surfacing was studied by scanning electron microscopy. A multiple increase in nanohardness and Young elastic modulus of the welded layer was revealed during electron-beam treatment according to the base material. It was found that the maximum hardening effect is observed at surfacing by a flux-cored wire containing 4.5 % of boron. It is shown that on the weld deposit surface formed by the wire with 4.5% of boron and additionally irradiated with an intense pulsed electron beam, the formation of a microcrack system on the surface of irradiation was revealed. Investigations of weld deposits, formed by non-boron-containing powder wires, have shown the absence of microcracks on the modified surface after pulsed electron beam treatment. The increase in the strength properties of the deposited layer modified by the electron beam is due to the formation of structures which crystallite sizes vary from tenths of a micrometer to one micrometer and contain second phases (borides, carbides, carbborides). A significant spread of the values of the nanohardness and the Young elastic modulus was established, which was apparently due to the inhomogeneous distribution of the strengthening phases.

Combined surface modification of commercial aluminum

The paper analyzes research data on the structure and properties of surface layers of commercially pure A7-grade aluminum subjected to treatment that combines deposition of a thin metal film, intense pulsed electron beam irradiation, and nitriding in low-pressure arc plasma. The analysis shows that the combined method of surface modification provides the formation of a multilayer structure with submicro- and nano-sized phases in the material through a depth of up to 40 μm, allowing a manifold increase in its surface microhardness and wear resistance (up to 4 and 9 times, respectively) compared to the material core. The main factors responsible for the high surface strength are the saturation of the aluminum lattice with nitrogen atoms and the formation of nano-sized particles of aluminum nitride and iron aluminides.

Surface characterization and tribological properties of WC-Ni cemented carbide irradiated by high intensity pulsed electron beam

Surface characterization of WC-13Ni cemented carbide irradiated by high intensity pulsed electron beam (HIPEB) at energy density of 3–34 J/cm2 with 10 pulse was investigated by using scanning electron microscope (SEM), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and Vickers tester. The surface tribological properties were measured by a block-on-ring tribometer. It was found that the HIPEB irradiation induced surface remelting and Ni selective ablation, resulting in the phase transformation from hexagonal α-WC to metastable phases, i.e. face centered cubic β-WC1-x and hexagonal α-W2C, and the formation of some defects such as microcracks and blow holes, and then the microstructural changes provided hardening and softening in different degree on the irradiated surface. The friction coefficient of irradiated samples reduced from 0.8 of the original WC-13Ni cemented carbide to 0.5, and the specific wear rate decreased to 3.8 × 10−7 mm3/Nm from 1.2 × 10−6 mm3/Nm, showing the surface tribological properties of HIPEB irradiated WC-13Ni cemented carbide is not only related to the surface hardening, but also with the surface microstructure.

Energy spectrum analysis for intense pulsed electron beam

AbstractAs the energy spread of intense pulsed electron beams (IPEB) strongly influences the irradiation effects, it has been of great importance to characterize the IPEB energy spectrum. With the combination of Child–Langmuir law and Monte Carlo simulation, the IPEB energy spectrum has been obtained in this work by transformation from the accelerating voltage applied to the diode. To verify the accuracy of this simple algorithm, a magnetic spectrometer with an imaging plate was designed to test the IPEB energy spectrum. The measurement was completed with IPEB generated by explosive emission electron diode, the pulse duration, maximum electron energy, total beam current being 80 ns, 450 keV, and 1 kA, respectively. The results verified the reliability of the above analysis method for energy spectrum, which can avoid intercepting the beam, and at the same time significantly improved the energy resolution. Some calculation and experimental details are discussed in this paper.

Structural and Phase Transformations in Ti-B<sub>4</sub>C System Formed when Melting the Composition Film/Substrate by an Intense Electron Beam

The "(Ti) film/(В4С ceramics) substrate" system was investigated after irradiation by an intense pulse electron beam. It was found that the multiphase structure crystallized on the eutectic reaction was formed in the surface layer of the film/substrate system. It was shown that high-speed metallization of the surface layer in the В4С ceramics leads to increase of its fracture toughness.

Structural Phase Transformations of the Surface Layer of SiC Ceramics Irradiated by Intense Electron Beam

Experimental investigations have been carried out to determine structural and phase transformations of a surface layer in SiC ceramics samples irradiated by an intense pulse electron beam of submillisecond duration. It was shown that electron beam modification of the surface layer of the SiC ceramics was followed by improvement of mechanical characteristics of the material. The suggestions have been made to explain this effect.

Increase of Fatigue Life of Titanium VT1-0 after Electron Beam Treatment

The processing of commercially pure titanium VT1-0 with high intensity pulsed electron beam was carried out and the mode of irradiation allowing the increase in fatigue life of the material was revealed. Structure investigations of modified layer and fracture surface of commercially pure titanium samples subjected to fatigue multicycle tests were implemented. By methods of scanning electron microscopy the structural transformations responsible for increase in fatigue life of titanium irradiated with high intensity pulsed electron beam were revealed. It was shown that irradiation of commercially pure titanium of grade VT1-0 with high intensity electron beam (25 J/cm2, 150 μs, 3 pulses) resulted in the refinement of grain structure, formation of multilayer structure. Irradiation facilitated the formation of additional structural levels of micro and nanosize range in surface layer.

Fractography of Fatigue Fracture Surface in Silumin Subjected to Electron-Beam Processing

The surface modification of the eutectic silumin with high-intensity pulsed electron beam has been carried out. Multi-cycle fatigue tests were performed and irradiation mode made possible the increase in the silumin fatigue life more than 3.5 times was determined. Studies of the structure of the surface irradiation and surface fatigue fracture of silumin in the initial (unirradiated) state and after modification with intense pulsed electron beam were carried out by methods of scanning electron microscopy. It has been shown, that in mode of partial melting of the irradiation surface the modification process of silicon plates is accompanied by the formation of numerous large micropores along the boundary plate/matrix and microcracks located in the silicon plates. A multi-modal structure (grain size within 30-50 μm with silicon particles up to 10 μm located on the boundaries) is formed in stable melting mode, as well as subgrain structure in the form of crystallization cells from 100 to 250 μm in size). Formation of a multi-modal, multi-phase, submicro- and nanosize structure assisting to a significant increase in the critical length of the crack, the safety coefficient and decrease in step of cracks for loading cycle was the main cause for the increase in silumin fatigue life.

Modification of the titanium film–aluminum substrate system by a high-intensity pulsed electron beam with a submillisecond duration

Numerical simulation of the thermal processes that occur during doping of an Al surface with titanium by the method of liquid-phase mixing of a film–substrate system using an intense pulsed electron beam is carried out. As a result of our studies, it is shown that melting of the Ti-film–Al-substrate system makes it possible to form a multiphase submicrocrystalline structure with high strength and tribological properties in the surface layer.

Structure and Properties of a Titanium Film – Aluminum Substrate System Alloyed by an Intense Pulsed Electron Beam

The structure and properties of a Ti film – Al substrate system alloyed by an intense pulsed electron beam are studied. It is shown that electron beam melting of this system provides the formation of a multiphase submicrocrystalline structure with high strength and tribological properties in the surface layer. Irradiation modes, which allow an increase in the microhardness of the material and a decrease in its wear rate, are defined. Physical substantiation of this phenomenon is given.

Numerical Simulation of Thermal Processes Involved in Surface Alloying of Aluminum with Titanium by an Intense Pulsed Electron Beam

The temperature fields arising in a Ti film – Al substrate system and bulk Ti specimen irradiated with a submillisecond intense electron beam are calculated in the one-dimension approximation. It is found that the temperature fields in the irradiated bulk Ti specimen and Ti film – Al substrate system differ greatly. Electron beam irradiation conditions which allow solid-phase and liquid-phase alloying of aluminum with titanium are defined

The Analysis of the Mechanisms for Plasticization of Boron Carbide Ceramics Irradiated by an Intense Electron Beam

Is has been shown that irradiation of the sintered ceramics on the basis of boron carbide with an intense pulsed electron beam leads to formation of non-porous polycrystalline structure. The specific elements of a sub-grain structure of the irradiated ceramics are micro-twins. It has been determined that the main failure mechanism of the sintered ceramics is an intercrystalline fracture. The irradiation of ceramics has led to mainly transcrystalline fracture.