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By the metho ds of modern physical materials science the change in structural-phase state of AlCoCrFeNi high-entropy alloy (HEA) of nonequiatomic composition obtained by the metho ds of wire arc additive technology (WAAM) after irradiation by electron beams with energy density of 10–30 J/cm2, durality of 50 µs, frequency 0.3 s–1 is studied. In the initial state the alloy had a dendritic structure indicating the inhomogeneous distribution of elements. It is shown that electron beam processing forms the structure of high-velocity cellular crystallization with cell size of 100–200 nm, along boundaries of which the nano dimensional (15–30 nm) inclusions of the second phase enriched in Cr and Fe atoms are located. [ABSTRACT FROM AUTHOR]

A mathematical model has been developed for the external uniformly distributed thermal effect on the surface of a flat bilayer element made of optical glass K108 and oxide coating with Al2O3, MgO, taking into account the temperature dependencies of their thermophysical properties (volumetric heat capacity and thermal conductivity). Critical values of external thermal impact parameters (heat flows and durations of their action) leading to the destruction of coatings (crack formation, detachment, delamination, etc.) have been determined. The problem of implementing a uniformly distributed thermal effect along the surface of the oxide coating using a system of fixed ribbon electron flows (REF) has been solved. These REFs are incorporated as a programmatically controlled module into the equipment of modern electron-beam devices. Permissible processing regimes for coating surfaces have been defined (the number of REFs, controlled parameters for each REF such as current, accelerating voltage, and distance to the processed surface). These regimes allow to improve their operational characteristics and prevent potential damage under extreme operating conditions of devices (elevated heating temperatures, thermal shock effects, etc.). Electron-beam processing of extended elements made of optical glass and ceramics, piezoceramic elements, as well as optical elements with coatings of metal oxides, is considered potentially capable of qualitatively processing their surfaces using a system of fixed REF. These REF can serve as the elemental basis in microoptics, integrated and fiber optics, functional electronics, and other fields of precision instrument engineering. [ABSTRACT FROM AUTHOR]

The effect of surface treatment using an electron beam is explored as a factor influencing the nature and the rate of fatigue fracture propagation in titanium nickelide samples undergoing cyclic stretching under a low-cycle loading regime before and after irradiation with low-energy high-current electron beam (L-EHCEB). A correlation is established between the stage of fatigue fracture propagation and the stage of forming deformation zones on the fracture surfaces in unirradiated and in irradiated samples. The surfaces of the samples are treated using the electron beam installation RITM-SP having the following parameters of electron beam: energy density ES = 3.7 J/cm2, pulse duration τ = 2.5 μs, number of pulses n = 5. The difference in propagation sequence of main fatigue fractures is revealed under cyclic stretching of unirradiated and irradiated titanium nickelide samples. Preferential mechanisms of quasi-static and fatigue fracture are established at various stages of fracture propagation. It is shown that LEHCEB treatment shifted both the onset of fatigue destruction of material and all the following stages by ΔN ≥ +3000, increasing, thereby, the cycling resistance of samples by a factor of ~1.5. The greatest impact of surface modification is observed at stage I of fatigue fracture propagation. At this stage, the low propagation rate of fatigue fractures in irradiated samples results in increasing the duration of the stage as compared with unirradiated samples. The conclusion is made that, in order to increase the resilience of titanium nickelide samples effectively using LEHCEB treatment, it is required to set up conditions to increase the number of cycles before the start of stage I and to maximize the duration of this stage. [ABSTRACT FROM AUTHOR]

The efficiency of food irradiation depends on the accuracy of the irradiation dose range that is sufficient for inhibiting microbiological growth without causing an irreversible change to the physical and chemical properties of foods. This study suggests that the concentration of hemoglobin derivatives can be used as a criterion for establishing the limit for chilled beef irradiation at which irradiation-induced oxidation becomes irreversible. The express spectrophotometry method for estimating the hemoglobin derivative concentration shows a nonlinear increase in methemoglobin concentration from 15% to 50% in beef irradiated by accelerated electrons with the doses ranging from 250 Gy to 10,000 Gy. The monitoring of the hemoglobin derivative concentration for three days after irradiation shows nonmonotonous dependencies of methemoglobin concentration in beef in the storage time since the oxidation of hemoglobin occur as a result of irradiation and biochemical processes in beef during storage. The proposed method based on the quantitative analysis of the hemoglobin derivative concentration can be used to estimate the oxidation level for irradiation of foods containing red blood cells. The study proposes a model that describes the change in hemoglobin derivative concentration in beef after irradiation considering that oxidation of hemoglobin can be triggered by the direct ionization caused by accelerated electrons, biochemical processes as a result of bacterial activity, and reactive oxygen species appearing during irradiation and storage. This research throws light on the mechanisms behind food irradiation during storage that should be taken into account for selecting the optimal parameters of irradiation. [ABSTRACT FROM AUTHOR]

The paper studies application of electron beam in a technology of high-speed sintering of hard alloy billets made of secondary raw materials as well as high-performance equipment developed at the E.O. Paton Electric Welding Institute of the NAS of Ukraine for the implementation of this technology. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of 17%Cr-19%Mn-0.53%N high-nitrogen austenitic stainless steel with a 25 µm thick dispersion-hardened near-surface layer intended for orthopedic applications. It was modified using a mechanical–thermal treatment (MTT) that included both friction processing and subsequent electron beam processing. The friction processing enabled the formation of a microstructure with a high dislocation density and strain twins, and it also initiated strain aging in the near-surface layer. At this stage, the hardening was achieved via the formation of CrN particles coherent to the matrix with the face-centered cubic (FCC) lattice and via the relaxation of internal stresses. After electron beam processing, the volume fraction of the nanodispersed phases increased. In the near-surface layer, a highly dispersed microstructure with a grain size of 3 μm, reinforced with CrN and Fe2N nanoparticles, was observed using transmission electron microscopy. The MTT increased the microhardness of the surface layer, and this contributed to the enhancement in both the H/E and H3/E2 ratios. This indicated an improvement in the crack resistance of the steel under frictional loads. The MTT also enhanced both the yield point (up to 580 MPa) and the wear resistance (by 50% to 100%, depending on the applied load) compared with those of the same steel after it had undergone quenching. In addition, the wear resistance was many times greater than that of the Ti-6Al-4V alloy typically used for manufacturing orthopedic implants. After the MTT, the properties of the near-surface layer of the steel indicated its suitability for biomedical applications. [ABSTRACT FROM AUTHOR]

This study focuses on the influence of pre-planting irradiation on the development, health, and yield of seed potatoes infected with Rhizoctonia solani. The research was prompted by the need to ensure crop security and sustainability in the modern-day environment, which calls into question the future sufficiency of crop yields. Considering that the focus has shifted to non-chemical methods of crop treatment at all plant development stages in response to more stringent regulations governing potato production, it is particularly important to refine physics-based methods to suppress fungal diseases caused by Rhizoctonia solani. Irradiation of tubers with 20–150 Gy inhibited the potato development phases and the doses exceeding 150 Gy completely suppressed the potato sprouting. Doses ranging from 20 Gy to 100 Gy decreased the quantity of large tubers by 10–20% on average while the number of medium and small tubers increased by 5–15% and 3–10%, respectively. Irradiation of seed potatoes also decreased the sclerotia and non-sclerotia forms of diseases caused by Rhizoctonia solani in the harvested tubers. It was found that 1 MeV electron irradiation with doses ranging from 20 Gy to 30 Gy is the most efficient for the pre-planting treatment of seed potatoes since the penetration of low-energy accelerated electrons into the upper layers of potato tubers ensures the suppression of diseases caused by Rhizoctonia solani by at least 10% from the value of non-irradiated samples and prevents the reduction of total yield allowing for a maximum of 25% loss. [ABSTRACT FROM AUTHOR]

Abstract—The effect of electron-beam treatment (EBT) and heat treatment (HT) of silica-based aggregates and mineral additives in Portland cement mortars on the intensity of alkali-silica reactions (ASRs) with their participation, which are dangerous for concrete structures, is studied. It is established that heating to a temperature of 900°C and the EBT of sand free of alkali-reactive inclusions, leads to a significant increase in the reactivity of cement-sand mortar mixtures, which increases with an increase in the absorbed dose and a corresponding increase in the content of acid hydroxyl groups on the sand surface. In the case of sand containing reactive inclusions of chalcedony, EBT leads to an increase in reactivity, and HT, to a decrease. Treatment of microsilica and metakaolin mineral additives capable of ASR inhibition leads to an increase in their inhibitory effect. The results obtained are promising for modeling the expansion of concrete as a result of ASR and increasing their resistance to fracture in alkaline media. [ABSTRACT FROM AUTHOR]

Together with the mechanical properties, the degradation rate is an important factor for biodegradable implants. The ZKX50 Mg alloy is a suitable candidate to be used as a biodegradable implant due to its favorable biocompatibility and mechanical properties. Current research investigates the degradation rate and corrosion behavior of the ZKX50 as a function of the microstructure constituents and their morphology. Since grain refinement is the main strengthening mechanism for the ZKX50, the effect of the microstructure refinement on the corrosion rate was studied by applying electron beam processing (EBP) and friction stir processing (FSP) on the ZKX50 cast alloy. To study the effect of the microstructure constituents and their morphology a subsequent solution heat treatment (HT) was applied to the processed samples. The results show that the EBP and FSP lead to a uniform and remarkably refined microstructure of the ZKX50 alloy and homogeneous distribution of the intermetallic phases. The results of electrochemical corrosion tests together with the microstructure characterization show that microgalvanic corrosion is the predominant mechanism that occurs between the Ca2Mg6Zn3 intermetallic phase and α-Mg matrix. According to the results attained through the electrochemical tests, the EBPed-HT ZKX50 alloy shows higher corrosion resistance compared to all other conditions immersed in 0.5 wt.% NaCl solution. The dissolution and spheroidizing of Ca2Mg6Zn3 particles during the solution heat treatment provides higher corrosion resistance mainly by decreasing the microgalvanic corrosion. The microstructure of the heat-treated samples does not show a significant grain coarsening which can degrade the enhancement of the mechanical properties achieved by the EBP and FSP.

The objective of this work is to study for the first time the combination of electron beam (EB) surface structuring and plasma electrolytic oxidation (PEO) with the aim of providing a multiscale topography and bioactive surface to the Ti6Al4V alloy for biomedical applications. Ca and P-containing coatings were produced via 45 s PEO treatments over multi-scale EB surface topographies. The coatings morphology and composition were characterized by a means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The effect on the previous EB topography was evaluated by means of a 3D optical profilometry and electrochemical response via potentiodynamic polarization tests. In general, the PEO process, morphology, composition and growth rate of the coatings were almost identical, irrespective of the topography treated. Minimal local differences were found in terms of morphology, and the growth rate were related to specific topographical features. Nevertheless, all the PEO-coated substrates presented essentially the same corrosion resistance. Electrochemical tests revealed a localized crevice corrosion susceptibility of all the bare EB topographies, which was successfully prevented after the PEO treatment. [ABSTRACT FROM AUTHOR]

The AK5M2 aluminum alloy was investigated following surface modification involving deposition of a titanium film with subsequent electron beam irradiation. The strength characteristics of the alloy according to tension to failure are determined. Changes in the crystal lattice period of the Al and Al3Ti phases depending on the electron beam energy density are investigated and analyzed. Based on the experimental results, the most effective modes of electron beam processing were selected to increase the obtained mechanical properties of the alloy. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of 17%Cr-19%Mn-0.53%N high-nitrogen austenitic stainless steel with a 25 µm thick dispersion-hardened near-surface layer intended for orthopedic applications. It was modified using a mechanical–thermal treatment (MTT) that included both friction processing and subsequent electron beam processing. The friction processing enabled the formation of a microstructure with a high dislocation density and strain twins, and it also initiated strain aging in the near-surface layer. At this stage, the hardening was achieved via the formation of CrN particles coherent to the matrix with the face-centered cubic (FCC) lattice and via the relaxation of internal stresses. After electron beam processing, the volume fraction of the nanodispersed phases increased. In the near-surface layer, a highly dispersed microstructure with a grain size of 3 μm, reinforced with CrN and Fe2N nanoparticles, was observed using transmission electron microscopy. The MTT increased the microhardness of the surface layer, and this contributed to the enhancement in both the H/E and H3/E2 ratios. This indicated an improvement in the crack resistance of the steel under frictional loads. The MTT also enhanced both the yield point (up to 580 MPa) and the wear resistance (by 50% to 100%, depending on the applied load) compared with those of the same steel after it had undergone quenching. In addition, the wear resistance was many times greater than that of the Ti-6Al-4V alloy typically used for manufacturing orthopedic implants. After the MTT, the properties of the near-surface layer of the steel indicated its suitability for biomedical applications.

The efficiency of food irradiation depends on the accuracy of the irradiation dose range that is sufficient for inhibiting microbiological growth without causing an irreversible change to the physical and chemical properties of foods. This study suggests that the concentration of hemoglobin derivatives can be used as a criterion for establishing the limit for chilled beef irradiation at which irradiation-induced oxidation becomes irreversible. The express spectrophotometry method for estimating the hemoglobin derivative concentration shows a nonlinear increase in methemoglobin concentration from 15% to 50% in beef irradiated by accelerated electrons with the doses ranging from 250 Gy to 10,000 Gy. The monitoring of the hemoglobin derivative concentration for three days after irradiation shows nonmonotonous dependencies of methemoglobin concentration in beef in the storage time since the oxidation of hemoglobin occur as a result of irradiation and biochemical processes in beef during storage. The proposed method based on the quantitative analysis of the hemoglobin derivative concentration can be used to estimate the oxidation level for irradiation of foods containing red blood cells. The study proposes a model that describes the change in hemoglobin derivative concentration in beef after irradiation considering that oxidation of hemoglobin can be triggered by the direct ionization caused by accelerated electrons, biochemical processes as a result of bacterial activity, and reactive oxygen species appearing during irradiation and storage. This research throws light on the mechanisms behind food irradiation during storage that should be taken into account for selecting the optimal parameters of irradiation.

This study focuses on the influence of pre-planting irradiation on the development, health, and yield of seed potatoes infected with Rhizoctonia solani. The research was prompted by the need to ensure crop security and sustainability in the modern-day environment, which calls into question the future sufficiency of crop yields. Considering that the focus has shifted to non-chemical methods of crop treatment at all plant development stages in response to more stringent regulations governing potato production, it is particularly important to refine physics-based methods to suppress fungal diseases caused by Rhizoctonia solani. Irradiation of tubers with 20–150 Gy inhibited the potato development phases and the doses exceeding 150 Gy completely suppressed the potato sprouting. Doses ranging from 20 Gy to 100 Gy decreased the quantity of large tubers by 10–20% on average while the number of medium and small tubers increased by 5–15% and 3–10%, respectively. Irradiation of seed potatoes also decreased the sclerotia and non-sclerotia forms of diseases caused by Rhizoctonia solani in the harvested tubers. It was found that 1 MeV electron irradiation with doses ranging from 20 Gy to 30 Gy is the most efficient for the pre-planting treatment of seed potatoes since the penetration of low-energy accelerated electrons into the upper layers of potato tubers ensures the suppression of diseases caused by Rhizoctonia solani by at least 10% from the value of non-irradiated samples and prevents the reduction of total yield allowing for a maximum of 25% loss.

The electroerosion-resistant coatings of CuO–Ag and ZnO–Ag systems were obtained on the Cu surface. Formation of coating was caused by the processing of copper surface with plasma formed in electrical explosion of silver foil with weighed sample of copper oxide or zinc oxide. After electroexplosion spraying, the electron-beam treatment of coatings was performed. The nanohardness, Young modulus, wear resistance, friction coefficient, and electrical erosion resistance of the formed coatings were studied. All studied properties exceed those of copper. Electrical erosion coatings were studied by the methods of scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. It became possible to achieve the high level of operational properties of electrical erosion coatings due to their nanostructurization. Structure of coating is formed by cells of high-speed crystallization. The size of cells varies within the range from 150 nm to 400 nm. The cells are separated by interlayers of the second phase whose thickness varies as 15–50 nm. By method of atomic force microscopy, the separate particles of ZnO or CuO of different shapes and 10–15 nm in size chaotically located in silver matrix were revealed as well as spherical particles of ZnO or CuO in size of 2–5 nm. The total thickness of coatings is 60 μm. The complex of studies we have carried out permits to recommend the integrated processing for strengthening the switch copper contacts of powerful electrical networks.

Together with the mechanical properties, the degradation rate is an important factor for biodegradable implants. The ZKX50 Mg alloy is a suitable candidate to be used as a biodegradable implant due to its favorable biocompatibility and mechanical properties. Current research investigates the degradation rate and corrosion behavior of the ZKX50 as a function of the microstructure constituents and their morphology. Since grain refinement is the main strengthening mechanism for the ZKX50, the effect of the microstructure refinement on the corrosion rate was studied by applying electron beam processing (EBP) and friction stir processing (FSP) on the ZKX50 cast alloy. To study the effect of the microstructure constituents and their morphology a subsequent solution heat treatment (HT) was applied to the processed samples. The results show that the EBP and FSP lead to a uniform and remarkably refined microstructure of the ZKX50 alloy and homogeneous distribution of the intermetallic phases. The results of electrochemical corrosion tests together with the microstructure characterization show that microgalvanic corrosion is the predominant mechanism that occurs between the Ca 2 Mg 6 Zn 3 intermetallic phase and α-Mg matrix. According to the results attained through the electrochemical tests, the EBPed-HT ZKX50 alloy shows higher corrosion resistance compared to all other conditions immersed in 0.5 wt.% NaCl solution. The dissolution and spheroidizing of Ca 2 Mg 6 Zn 3 particles during the solution heat treatment provides higher corrosion resistance mainly by decreasing the microgalvanic corrosion. The microstructure of the heat-treated samples does not show a significant grain coarsening which can degrade the enhancement of the mechanical properties achieved by the EBP and FSP. [ABSTRACT FROM AUTHOR]

The increasing use of light alloys owing to their high performance makes magnesium alloys very attractive for the use in automotive and biomedical applications. However, it is well known that magnesium and its alloys have poor corrosion resistance in different atmospheric and aqueous environments. As a means of improving corrosion resistance through the microstructure modification, electron beam processing (EBP) was applied on the as-cast AZ91 magnesium alloy. To evaluate the microstructure influence on the corrosion-resistant, the EB processed samples underwent a solution heat treatment and an artificial aging heat treatment. Four different obtained microstructures were investigated by standard microscopy and electrochemical corrosion tests to evaluate the microstructure and its effects on the corrosion resistance of AZ91 alloy. The EBPed specimens show a significant microstructure refinement and homogenous distribution of β-phase at the grain boundaries surrounded by supersaturated α-Mg which acts as a barrier against corrosion. The electrochemical corrosion test of the samples immersed in 3.5 wt% NaCl after 4 weeks indicates that the EBP improves the corrosion resistance of the alloy due to the nobler corrosion potential of supersaturated α-Mg and more stable protective hydroxide films compared to the heat-treated and as-cast conditions.

Vacoflux-49 (Fe-49% Co-49% V-2%) is used in torque, sonar and gyroscopic sensors applications due to excellent magnetic properties (high saturation magnetisation, low coercivity and high Curie temperature). In this study, the shape, size and characteristics of different thermal zones and the microstructural evolution during electron beam melting and welding of Vacoflux-49 material are studied. The experimental studies on melting have been carried out with under-focussed, focussed and over focussed electron beam. In the case of the under-focussed and over-focused beam, no evaporated zone is found. In the case of focussed beam, a shallow conical-shaped evaporated zone, a choked funnel-shaped fusion zone, a conical shaped partially melted zone and the heat-affected zone are observed. The solidified melt pool in terms of shape, size and microstructure of different zones are investigated for the focussed beam. The grains in the fusion zone appear wavy having crest and trough. The fusion zone microstructure also shows the formation of solidification rings. From the electron beam welding experiments performed for joining two Vacoflux-49 plates (continuous welding), it is found that the weldment shape is similar to the spot melting and re-solidification experiments. The grain growth in different zones in the welding sample is also examined.

The study reports on the electron-beam processing (energy of accelerated electrons 17 keV, electron beam energy density ES = 10, 20, 30, 40, and 50 J/cm2, pulse duration 50 and 200 μs) of Al-10wt%Si-2wt%Cu alloy (silumin) surface. The important outcome to emerge from the study is a correlation between surface microhardness and electron beam energy density. As revealed, a maximal microhardness value is at ES = (30–40) J/cm2, being more than 1.6 times higher than the characteristic of the untreated material. The research has pointed out the electron-beam processing of silumin at ES = 10 J/cm2 causes the intensive destruction and microcracking along grain boundaries with particles of intermetallic compounds, as well as the globularization of cementite lamellae in eutectics. The irradiation of silumin by an electron beam (ES = 30–50 J/cm2) is shown to bring about the origination of micropores in the surface of samples, the dissolution of silicon, the globularization of intermetallic inclusions; in addition, a sub-micro-sized crystal structure of high-speed cellular crystallization forms. Finally, the electron-beam processing of silumin leads to the saturation of Al-based crystal lattice with alloying and impurity elements.

The structural-phase states, microhardness, and tribological properties of hypoeutectic silumin after electron-beam treatment are studied by the methods of contemporary physical materials science. The object of the study is hypoeutectic АК10М2Н-type silumin containing 87.88 wt.% of Al and 11.1 wt.% of Si as the base components. The silumin surface is subjected to electron-beam treatment in six various regimes distinct in the density of electron-beam energy. The microhardness measurements of the modified silumin-surface layers enabled to determine three optimal impact regimes (with electron-beam energy densities of 25, 30, and 35 J/cm2), when the modified-layer microhardness exceeds that for the cast silumin. The obtained parameters are as follow: 0.86 ± 0.41 GPa for the cast state; 0.93 ± 0.52 GPa for 25 J/cm2; 0.97 ± 0.071 GPa for 30 J/cm2; 0.96 ± 0.103 GPa for 35 J/cm2. As found, the electron-beam treatment with the optimal parameters results in the formation of the surface whose mechanical and tribological characteristics sufficiently exceed corresponding values for the cast state of silumin. The atomic-force microscopy data correlate with the results on microhardness. The samples treated in the presented regimes are characterised with the fine-grained cellular structure and have the least roughness of the treated layer (of 17–33 nm) and substrate (of 45–57 nm) as compared to other regimes. As revealed, in the treated layer, the fine-grained, graded, and cellular structure is formed, and it transforms into the mixed-type structure when deepening away from the surface of treatment. Depending on the parameters of electron-beam treatment, the thickness of homogenized layer varies and reaches the maximum values of 100 μm at the energy density of 35 J/cm2. As detected, the modified layer is free from intermetallides and consists of the nanocrystalline structure of cellular crystallization. As assumed, these two factors are responsible for the increased mechanical and tribological characteristics of the modified layer. The formation mechanism for structure of cellular and columnar crystallization consisting in the initiation of thermocapillary instability over the ‘evaporated substance/liquid phase’ interface is offered. The mathematical model of the thermal effect of electron beam on the silumin-surface layers is developed.

Background: This technical brief discusses material degradation issues and potential remedies related to advanced thermoset composites manufacturing using a new out-of-autoclave consolidation and curing process called Electron Beam processing with Specialized Elastomeric Tooling for Resin Infusion (EB-SETRI). To provide context, the design process for EB-SETRI tooling based on finite element structural analysis and Monte Carlo simulations of EB attenuation within tooling materials is briefly described. Of particular interest in this paper is the elastomeric mask, since it exhibits significant changes in mechanical properties based on prior work. Methods: Samples of five different silicone blends (four different durometers and two different catalysts) and one urethane (elastomeric mask materials of choice) were irradiated by an EB source with 3.0-MeV maximum power to simulate the conditions experienced by EB-SETRI tooling during processing. Changes in surface hardness and compression modulus were measured using ASTM D575 and D2240 as a function of dosage. Results: Urethane embrittles and becomes unusable even at low dosages, whereas silicone generally hardens to a maximum level at higher dosages, presumably due to increased crosslinking density, and stiffens (modulus increases) linearly. The embrittlement of silicone is shown to be a result of the EB irradiation and not due to a temperature increase from energy absorption. Conclusions: Changes in elastomer mechanical properties confound process performance as a result, and several concepts for dealing with these changes are suggested. Although the experimental focus is on EB-SETRI, results apply to any manufacturing process that combines the use of EB irradiation and elastomers. [ABSTRACT FROM AUTHOR]

In this study, W–Zr surface alloys (SAs) were synthesized by low-energy high-current electron beam (LEHCEB) processing of preliminary deposited tungsten films on zirconium substrates in a single vacuum cycle. Then, their microstructure, as well as both chemical and phase compositions were investigated. Also, computer simulation of the dynamics of temperature fields was carried out. After LEHCEB processing of the Zr substrate with the preliminary deposited W film, the constituent element distributions were non-uniform over the surface of the W–Zr SA at the energy density of 3.5 J/cm2. Rising the energy density up to 5.5 J/cm2 resulted in a smoother and more homogeneous W–Zr SA. At the energy density of 3.5 J/cm2, the average tungsten content over the surface was 53 ± 39 at.%, while it was only 26 ± 2 at.% at 5.5 J/cm2. All W–Zr SAs consisted of the W phase (in different proportions), tungsten-rich solid solutions in the stabilized β-Zr phase, and the W 2 Zr intermetallic compound. The contents of the β-Zr and W 2 Zr phases enhanced with rising the energy density due to a greater amount of dissolved tungsten. Based on the obtained results, a scheme was proposed describing the formation of the SAs upon LEHCEB processing. • Tungsten films deposited on zirconium substrates were processed with electron beams. • Surface alloys consisted of β -Zr phase, fragments of the W films and W 2 Zr compound. • β -Zr solid solutions contained the maximum possible contents of dissolved tungsten. • Patterns and mechanisms of the formation of the surface alloys were discussed. [ABSTRACT FROM AUTHOR]

Copyright of Progress in Physics of Metals / Uspehi Fiziki Metallov is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasing use of light alloys owing to their high performance makes magnesium alloys very attractive for the use in automotive and biomedical applications. However, it is well known that magnesium and its alloys have poor corrosion resistance in different atmospheric and aqueous environments. As a means of improving corrosion resistance through the microstructure modification, electron beam processing (EBP) was applied on the as-cast AZ91 magnesium alloy. To evaluate the microstructure influence on the corrosion-resistant, the EB processed samples underwent a solution heat treatment and an artificial aging heat treatment. Four different obtained microstructures were investigated by standard microscopy and electrochemical corrosion tests to evaluate the microstructure and its effects on the corrosion resistance of AZ91 alloy. The EBPed specimens show a significant microstructure refinement and homogenous distribution of β-phase at the grain boundaries surrounded by supersaturated α-Mg which acts as a barrier against corrosion. The electrochemical corrosion test of the samples immersed in 3.5 wt% NaCl after 4 weeks indicates that the EBP improves the corrosion resistance of the alloy due to the nobler corrosion potential of supersaturated α-Mg and more stable protective hydroxide films compared to the heat-treated and as-cast conditions. [ABSTRACT FROM AUTHOR]

Vacoflux-49 (Fe-49% Co-49% V-2%) is used in torque, sonar and gyroscopic sensors applications due to excellent magnetic properties (high saturation magnetisation, low coercivity and high Curie temperature). In this study, the shape, size and characteristics of different thermal zones and the microstructural evolution during electron beam melting and welding of Vacoflux-49 material are studied. The experimental studies on melting have been carried out with under-focussed, focussed and over focussed electron beam. In the case of the under-focussed and over-focused beam, no evaporated zone is found. In the case of focussed beam, a shallow conical-shaped evaporated zone, a choked funnel-shaped fusion zone, a conical shaped partially melted zone and the heat-affected zone are observed. The solidified melt pool in terms of shape, size and microstructure of different zones are investigated for the focussed beam. The grains in the fusion zone appear wavy having crest and trough. The fusion zone microstructure also shows the formation of solidification rings. From the electron beam welding experiments performed for joining two Vacoflux-49 plates (continuous welding), it is found that the weldment shape is similar to the spot melting and re-solidification experiments. The grain growth in different zones in the welding sample is also examined. [ABSTRACT FROM AUTHOR]

The ability of electrons and atomic hydrogen (AH) to remove residual chlorine from PtCl2 deposits created from cis-Pt(CO)2Cl2 by focused electron beam induced deposition (FEBID) is evaluated. Auger electron spectroscopy (AES) and energy-dispersive X-ray spectroscopy (EDS) measurements as well as thermodynamics calculations support the idea that electrons can remove chlorine from PtCl2 structures via an electron-stimulated desorption (ESD) process. It was found that the effectiveness of electrons to purify deposits greater than a few nanometers in height is compromised by the limited escape depth of the chloride ions generated in the purification step. In contrast, chlorine atoms can be efficiently and completely removed from PtCl2 deposits using AH, regardless of the thickness of the deposit. Although AH was found to be extremely effective at chemically purifying PtCl2 deposits, its viability as a FEBID purification strategy is compromised by the mobility of transient Pt–H species formed during the purification process. Scanning electron microscopy data show that this results in the formation of porous structures and can even cause the deposit to lose structural integrity. However, this phenomenon suggests that the use of AH may be a useful strategy to create high surface area Pt catalysts and may reverse the effects of sintering. In marked contrast to the effect observed with AH, densification of the structure was observed during the postdeposition purification of PtCx deposits created from MeCpPtMe3 using atomic oxygen (AO), although the limited penetration depth of AO restricts its effectiveness as a purification strategy to relatively small nanostructures.

The structure, phase composition and tribological properties of surface layers of hypoeutectic silumin after the complex processing including the electroexplosion alloying with the yttrium oxide powder in different regimes and the subsequent electron beam processing have been analyzed by the methods of modern physical material science. With respect to the initial silumin the ≈20-fold increase in the wear resistance and ≈1.5-fold decrease in the friction coefficient have been detected. The complex processing is accompanied by the formation of the multiphase submicro—nanocrystalline layer up to 80 μm in thickness enriched by yttrium and oxygen atoms responsible for the multiple increase in the wear resistance. At the complex processing according to the first regime of electroexplosion alloying (EEA) (Y2O3 powder mass—0.0589 g, discharge voltage—2.8 kV) with the subsequent electron beam irradiation, the major phase of the modified layer is the solid solution based on Al (≈71.2 mass %), the remaining phases are SiO2, YAlO3, YSi2. The 1.5-fold increase in the mass of Y2O3 powder at EEA and 1.1-fold decrease in the discharge voltage is accompanied by the increase in the quantity of phases, the significant (more than 2.5-fold) decrease in the content of the solid solution based on Al, the ≈2.2-fold increase in the content of silicon oxide, the presence of yttrium oxide and metallic yttrium. [ABSTRACT FROM AUTHOR]

Copyright of Progress in Physics of Metals / Uspehi Fiziki Metallov is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The structural phase states and silumin's defect substructure of silumin hypoeutectoid composition subjected to electron beam processing with the following parameters: energy density—25 J/cm2, pulse duration—150 µs, number of pulses—3, pulsed repetition rate—0.3 Hz were analyzed by methods of modern physical material science. The irradiation of the surface leads to the melting of the surface layer, the structure formation of high-speed cellular crystallization of submicron dimentions and the repeated precipitation of the second phase particles. The cells formation of two types: those free from precipitations of the second phase and those containing the lamellar eutectic Al–Si was revealed. The cells are separated by the second phase interlayers containing the particles of Cu15Si14Al4Cu9, silicon and copper. As the distance from the surface of irradiation increases the layer containing the second phase inclusions of quasi—equilibrium shape are defined along with the crystallization cells. It is indicative of the occurance of the globularization processes of silumin's structure on electron beam processing. [ABSTRACT FROM AUTHOR]

By the method of modern physical material science (optic microscopy scanning and transmission electron microscopy) the analysis of structural phase states, the morphology of the second phase inclusions and defect substructure of Al-Si alloy (silumin) of hypoeutectic composition, subjected to electron beam processing was done with the following parameters: energy density 25-35 J/cm2, beam length 150 µs, pulse number - 3, pulse repetition rate - 0.3 Hz, pressure of residual gas (argon) 0.02 Pa. The surface irradiation results in the melting of the surface layer, the dissolution of boundary inclusions, the stricture formation of high speed cellular crystallization of submicron sizes, the repeated precipitation of the second phase nanodimentional particles. With the increased distance from the irradiation surface the layer containing the second phase inclusions of quasi-equilibrium shape along with the crystallization cells was revealed. It is indicative of the processes of Al-Si alloy structure globalization on electron beam processing. [ABSTRACT FROM AUTHOR]

Focused electron beam induced processing (FEBIP) is a suite of direct-write, high resolution techniques that enable fabrication and editing of nanostructured materials inside scanning electron microscopes and other focused electron beam (FEB) systems. Here we detail continuum techniques that are used to model FEBIP, and release software that can be used to simulate a wide range of processes reported in the FEBIP literature. These include: (i) etching and deposition performed using precursors that interact with a surface through physisorption and activated chemisorption, (ii) gas mixtures used to perform simultaneous focused electron beam induced etching and deposition (FEBIE and FEBID), and (iii) etch processes that proceed through multiple reaction pathways and generate a number of reaction products at the substrate surface. We also review and release software for Monte Carlo modeling of the precursor gas flux which is needed as an input parameter for continuum FEBIP models.