High Current Pulsed Electron Beam Research Articles

Mechanisms of deformation induced by high-current pulsed electron beam irradiation

AA2024 aluminum alloy was irradiated by a high-current pulsed electron beam with the following parameters: beam energy ∼0.3 MeV, current ∼2000A, pulse duration ∼5·10−6 s, beam diameter ∼3 cm. The thickness of the surface remelted layer reached 100 μm. Dynamic thermal stresses caused by irradiation, induced the development of deformation processes in the irradiated layer. Based on the study of surface morphology and structural state of the remelted layer, it was shown that deformation processes occur in the surface layer by the grain boundary sliding mechanism. The level of residual stresses in the irradiated layer was low and amounted to 34 MPa.

High-current pulsed electron beam modification on microstructure and performance of Cu/CuW diffusion bonding joints

High-current pulsed electron beam modification on microstructure and performance of Cu/CuW diffusion bonding joints

Microstructure and Properties of TiN/TiCN/Al2O3/TiN Coating Enhanced by High-Current Pulsed Electron Beam

In this work, a TiN/TiCN/Al2O3/TiN coating deposited onto cemented carbide matrix by chemical vapor deposition was irradiated by high-current pulsed electron beam (HCPEB). The influence of pulse times on the phase composition, microstructure, and mechanical properties of the coating investigated. The results showed that no new phase was produced, the grain size of the coating surface was refined, the surface became flat, and the surface roughness decreased after HCPEB treatment. The TiN/TiCN/Al2O3/TiN coating presented a smooth surface with good mechanical performance after HCPEB. A maximum hardness was obtained after 15 pulses, and the 15-pulse irradiated coating showed better wear resistance. The improvement in the coating’s performance after irradiation was mainly attributed to the formation of grain refinement and crystal defects, as well as the change of stress field inside the coating. The objective of this study was to evaluate the potential of HCPEB modification in the preparation of high-performance coating by analyzing the microstructure and property of coating under different pulses.

Microstructures and improved properties of Cu–Mo alloys induced by high current pulsed electron beam irradiation

In this paper, a Cu–Mo alloying layer with improved properties was fabricated by high current pulsed electron beam (HCPEB) irradiation. The microstructure of the modified layer was investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The microhardness and friction properties were also measured. After HCPEB irradiation, nano Mo particles, solid solution, and long-period superlattice structures were generated on the surface of Cu–Mo alloys, together with the formation of defect structures. These microstructures led to a significant increase in the surface hardness. The results of sliding wear tests indicated that the HCPEB-irradiated samples exhibited better properties compared with the initial one, which was attributed to the ultrafine Mo particles and the hardened surface.

Effect of high current pulsed electron beam on surface microstructure and properties of cold-rolled austenitic stainless steel

High current pulsed electron beam (HCPEB) was used to modify the surface microstructure and performance of AISI 304 stainless steel with different cold-rolling deformation. The phase, microstructure, microhardness, and corrosion performance were characterized and analyzed after cold-rolling and HCPEB treatment. The results show that after cold-rolling, deformation-induced martensites (DMs) are generated in the deformation twin lamellae or at the intersections of multiple twin lamellae, resulting in a grid-like morphology, smaller size, and a certain orientation relationship with the parent austenite. The content of DMs increases with increasing cold-rolling deformation. After HCPEB treatment, many craters with different sizes and similar densities are produced on the sample surface, and the DMs are transformed into austenite again in the surface layer. The difference is that the grain size of the regenerated austenite after HCPEB is much smaller than that of the initial austenite (before cold-rolling). Such high-density equiaxed ultrafine grains (UFGs) of austenite formed after HCPEB present a twin feature, which is the inheritance of the orientation relationship between DMs and austenite formed during rolling. HCPEB treatment can effectively reshape the phase and microstructure of the surface layer of the cold-rolled deformed austenitic steel but reduce the surface hardness and increase pitting corrosion tendency.

A Tutorial on the One-Dimensional Theory of Electron-Beam Space-Charge Effect and Steady-State Virtual Cathode

The space-charge effects of pulsed high-current electron beams are very important to high-power particle beam accelerators and high-power microwave devices. The related physical phenomena have been studied for decades, and a large number of informative publications can be found in numerous scientific journals over many years. This review article is aimed at systematically summarizing most of the previous findings in a logical manner. Using a normalized one-dimensional mathematical model, analytical solutions have been obtained for the space-charge-limited current of both planar diode and drifting space. In addition, in the case of a beam current higher than the space-charge-limited current, the virtual cathode behavior and beam current reflection are quantitively studied. Furthermore, the criteria of steady-state virtual cathode formation are investigated, which leads to the physical understanding of the unstable nature of the virtual cathode. This review article is expected to serve as an integrated source of related information for young researchers and students working on high-power microwaves and pulsed particle beams.

Hot corrosion behavior of NiCoCrAlYSi laser cladding coating modified using high-current pulsed electron beam in different corrosive salt environments

The investigation focused on microstructural changes and hot corrosion behavior in various salt environments (Na2SO4 + 25 wt% K2SO4 and Na2SO4 + 25 wt% NaCl) at 900 °C of NiCoCrAlYSi laser cladding coatings before and after high-current pulsed electron beam (HCPEB) irradiation. HCPEB treatment effectively eliminated imperfections like micropores and segregation of the components, creating a remelted layer with high-density dislocations and nanostructure. The irradiated impacts including polishing, purification, composition homogenization, and grain refinement facilitated the development and self-repair of a compact and tenacious oxide scale. This enhanced oxide layer effectively mitigates extensive corrosive media erosion. The utilization of HCPEB treatment has shown significant potential in enhancing the hot corrosion resistance of NiCoCrAlYSi laser claddings.

The Positron Spectroscopy of the Zr–1Nb Alloy after Modification by High-Current Pulsed Electron Beam

The Positron Spectroscopy of the Zr–1Nb Alloy after Modification by High-Current Pulsed Electron Beam

The effect of low-energy high-current pulsed electron beam irradiation on the structure, phase composition and mechanical properties of Ni3Al and Ni3Al-TiC composites

Using scanning and transmission electron microscopy, X-ray diffraction, indentation and bending tests we studied the evolution of microstructure, phase composition and mechanical properties of TiC-free Ni3Al and Ni3Al-TiC composites (TiC content was 10 and 30 vol%) fabricated by self-propagating high-temperature synthesis (SHS) under pressure induced by low-energy high-current pulsed electron beam (LEHCEB) irradiation with the surface energy density of 8, 12 and 18 J/cm2. It was found that the irradiation results in the improvement of phase composition of the near-surface layer by way of the increase of yield of SHS reaction. LEHCEB irradiation enables formation of nanocomposite structure in the near-surface layer of Ni3Al-TiC composites with decreased grain size of Ni3Al matrix, refined TiC particles and increased volume fraction of TiC. This structure leads to the increase of microhardness but decrease of strength under bending. Two mechanisms of TiC particles refining are suggested. The effect of surface energy density on the manifestation degree of the found phenomena is discussed. The contribution of different hardening mechanisms to the overall hardening is considered.

Improved mechanical and tribological properties of TiAlN coatings by high current pulsed electron beam irradiation

High current pulsed electron beam (HCPEB) irradiation is an important surface engineering technique, which has been proved to be valid in modifying the surface microstructure and properties of various materials. In this work, HCPEB was employed to irradiate TiAlN coatings. The microstructure, mechanical and tribological properties of both original and irradiated TiAlN coatings were investigated. The results showed that the surface roughness of the TiAlN coatings first increased with 5 pulses of HCPEB irradiation, and then gradually declined with a further increase in pulse numbers. Compared with the original coating, the coating irradiated by 15 pulses demonstrated superior hardness (up to 33.4 GPa) and adhesion strength (112N), excellent wear resistance (wear rate of 3.3 × 10−6 mm3/Nm) and low friction coefficient (0.37). It is believed that the grain refinement, formation of the transition zone and adjustment of residual stresses after 15 pulses of HCPEB treatment are responsible for the improvement in both mechanical and tribological properties of the TiAlN coatings. These findings might suggest the potential applications of HCPEB irradiation for surface modification and hardness improvement of hard nitride coatings.

Ultrafast transformation of natural graphite into self-supporting graphene as superior anode materials for lithium-ion batteries

Graphite possesses remarkable potential as an anode material for lithium-ion batteries, thanks to its superb electrical conductivity and eco-friendliness. Nevertheless, challenging issues persist, such as its low maximum theoretical lithium storage capacity and constraints associated with the regular layered structure, which impede its practical application and advancement. In this regard, we proposed a novel approach to enhance the energy storage performance of lithium-ion batteries, involving the modification of natural graphite through irradiation with a high-current pulsed electron beam (HCPEB). Microscopic observations revealed that during the in-situ transformation of graphite particles into self-supporting graphene nanosheets, the high temperature generated by HCPEB irradiation led to the formation of structural defects, including Stone Wales and double vacancy defects. Consequently, the modified natural graphite electrode (particle size 12 μm) exhibited a reversible capacity of 420.4 mAh/g at 0.2C and maintained 94.5% of its reversible capacity after 500 cycles. In comparison to unmodified graphite (particle size 12 μm), the SEI film displayed enhanced stability, significantly improving cycling performance. These findings demonstrated that the defective graphene nanosheet structure enhances lithium storage activity sites, enlarges layer spacing, and enhances lithium storage performance. This study presents an efficient and environmentally friendly method for producing superior anode materials for lithium-ion batteries.

Effect of High-Current Pulsed Electron Beam Irradiation on the Microstructure and Mechanical Properties of Multilayered TiN/TiCN/Al2O3 Coatings

Effect of High-Current Pulsed Electron Beam Irradiation on the Microstructure and Mechanical Properties of Multilayered TiN/TiCN/Al2O3 Coatings

Microstructural evolution of thermally grown oxide of an arc ion plated MCrAlX coatings after high-current pulsed electron beam treatment

An arc ion-plated NiCoCrAlYHfSi coating modified by a high-current pulsed electron beam (HCPEB) was examined in this study. The dynamic growth behavior and formation mechanisms of the thermally grown oxide (TGO) of the original and modified coatings were thoroughly compared by isothermal oxidation at 1050 °C. HCPEB irradiation led to the transformation of the rough original coating into a flat, smooth, and dense structure. Furthermore, Y-Al nanoparticles and high density of dislocations were also obtained in the modified layer. These modification characteristics can establish favorable conditions for the rapid accumulation and stable growth of the protective Al2O3 particles. With the extension of oxidation time, the CrO3 formed in the oxide film left many small pits after volatilization, but these pits were filled with Al2O3 particles. Compared with the oxide film of the original coating, the TGO of the modified coating is flat, continuous, and dense, and its growth rate is notably slower. Also, the growth of Ni, Cr, and Co rich oxides was expectantly restrained. Obviously, the HCEPB technique has the capacity to change the growth behavior of the TGO and significantly enhance the coating's resistance to high-temperature oxidation.

Hot corrosion behavior of NiCoCrAlY laser cladding coating on 17-4PH stainless steel before and after high-current pulsed electron beam irradiation

In this study, we employed high-current pulsed electron beam technology (HCPEB) to modify NiCoCrAlY coatings that were created via laser cladding on 17-4PH stainless steel. We compared and analyzed the hot corrosion behavior of the coatings before and after HCPEB irradiation using a molten salt of 75 wt. %Na2SO4 + 25 wt. %NaCl at 700 °C. We also elucidated the mechanism by which irradiation affects the hot corrosion performance of the coatings. Our findings demonstrate that the irradiated coating surface exhibited a dense remelting layer, which effectively prevented erosion by oxygen and molten salt, without any internal oxidation corrosion. Moreover, irradiation refined the grains on the coating surface and increased the diffusion rate of grain boundaries. Consequently, the irradiated coating formed laminated thermal growth oxides (TGO) during the hot corrosion process, with the interface between the TGO and the coating always covered by an Al2O3 layer. This TGO structure provided excellent protection, reduced the corrosion weight gain, and corrosion rate of the coating, and significantly improved the hot corrosion performance of the coating.

Impact of high-current pulsed electron beam modification on element diffusion and performance of Ti6Al4V/AISI 316 L stainless steel diffusion bonded joints

The diffusion bonding process between Ti6Al4V and 022Cr17NiMo2 stainless steel (AISI 316 L SS) was carried out under vacuum conditions, applying a 10 MPa load for 40 min within a temperature range of 800–900 °C. This study investigates the influence of high-current pulsed electron beam (HCPEB) modification on the microstructure at the interface and the shear strength of Ti6Al4V/AISI 316 L SS joints. After HCPEB pretreatment, a well-formed diffusion bond was achieved between Ti6Al4V and AISI 316 L SS at 900 °C. Through calculations, the diffusion coefficient and diffusion activation energy of Fe in the Ti6Al4V section were determined, which demonstrated that Fe exhibits higher diffusion rates in the HCPEB-modified joints. The modified joint, subjected to 900 °C, exhibited a maximum bond strength of 208 MPa, which is attributed to dispersion and solid solution strengthening. Consequently, the implementation of HCPEB modification proves effective in promoting element diffusion and enhancing the mechanical performance of the joints. The presence of abundant crystal defects, including vacancies, dislocations, and grain boundaries (GBs) generated by HCPEB, is believed to be responsible for the observed improvement in diffusion.

Effect of High Current Pulsed Electron Beam (HCPEB) on the Organization and Wear Resistance of CeO2-Modified Al-20SiC Composites.

This paper investigates the joint effect of high current pulsed electron beam (HCPEB) and denaturant CeO2 on improving the microstructure and properties of Al-20SiC composites prepared by powder metallurgy. Grazing Incidence X-ray Diffraction (GIXRD) results indicate the selective orientation of aluminum grains, with Al(111) crystal faces showing selective orientation after HCPEB treatment. Casting defects of powder metallurgy were eliminated by the addition of CeO2. Scanning electron microscopy (SEM) results reveal a more uniform distribution of hard points on the surface of HCPEB-treated Al-20SiC-0.3CeO2 composites. Microhardness and wear resistance of the Al-20SiC-0.3CeO2 composites were better than those of the Al matrix without CeO2 addition at the same number of pulses. Sliding friction tests indicate that the improvement of wear resistance is attributed to the uniform dispersion of hard points and the improvement of microstructure on the surface of the matrix after HCPEB irradiation. Overall, this study demonstrates the potential of HCPEB and CeO2 to enhance the performance of Al-20SiC composites.

Formation mechanism of craters on the surface of AA6111 aluminum alloy irradiated by quasi-relativistic high-current electron beam

The factors contributing to the formation of craters on the surface of the AA6111 aluminum alloy after processing with a high-current pulsed electron beam were investigated. Microstructural studies of the crater formation area were conducted both on the surface of the irradiated layer and on the cross-sectional side. Inhomogeneity in the distribution of alloying elements was observed both across the irradiated surface and along the cross-sectional surface of the irradiated alloy layer. The regularities of crystallization of phases in the presence of various alloying elements and their effects on the formation of crater geometry were identified. The size and shape of craters were analyzed, and it was determined that the depth of all craters was less than the thickness of the layer remelted by the high-current pulsed electron beam. A mechanism was proposed whereby the formation of craters in the AA6111 alloy is the result of uneven crystallization of the surface layer melted by the high-current pulsed electron beam.

Enhanced surface quality and properties of cold spray Al coating by high current pulsed electron beam treatment

In this paper, high current pulsed electron beam (HCPEB) irradiation was employed to improve the surface density and properties of cold spray Al coating. The effects of the energy density on the microstructure, phase composition, stress, microhardness, wear, and corrosion behavior of coatings as-fabricated were investigated. HCPEB remelting treatment has improved the surface defects of cold spray coatings. The microhardness of treated coatings is higher than that of untreated coating, and the highest microhardness of the treated coatings occurs in the subsurface layer of the coatings. The wear track width and depth of the treated coating were lower than those of the untreated sample. The corrosion potential of the treated samples increases from −1.12 v to −0.95 v, and the corrosion current density reduces from 15.64 µA/cm2 to 3.31 µA/cm2. Our results demonstrated the wear and corrosion resistance of the cold spraying Al coating were dramatically improved by HCPEB irradiation.

Combined Porous-Monolithic TiNi Materials Surface-Modified with Electron Beam for New-Generation Rib Endoprostheses.

TiNi alloys are very widely used materials in implant fabrication. When applied in rib replacement, they are required to be manufactured as combined porous-monolithic structures, ideally with a thin, porous part well-adhered to its monolithic substrate. Additionally, good biocompatibility, high corrosion resistance and mechanical durability are also highly demanded. So far, all these parameters have not been achieved in one material, which is why an active search in the field is still underway. In the present study, we prepared new porous-monolithic TiNi materials by sintering a TiNi powder (0-100 µm) on monolithic TiNi plates, followed by surface modification with a high-current pulsed electron beam. The obtained materials were evaluated by a set of surface and phase analysis methods, after which their corrosion resistance and biocompatibility (hemolysis, cytotoxicity, and cell viability) were evaluated. Finally, cell growth tests were conducted. In comparison with flat TiNi monoliths, the newly developed materials were found to have better corrosion resistance, also demonstrating good biocompatibility and potential for cell growth on their surface. Thus, the newly developed porous-on-monolith TiNi materials with different surface porosity and morphology showed promise as potential new-generation implants for use in rib endoprostheses.

Evolution of Microstructure and Mechanical Properties of NiCoCrAlY Coatings After High-Current Pulsed Electron Beam Irradiation

In this paper, the NiCoCrAlY coating prepared by laser cladding was modified by a high-current pulsed electron beam technique. Scanning electron microscopy and X-ray diffraction analysis were used to characterize the microstructure and composition of the coatings before and after irradiation, and then the changes in mechanical properties were revealed by comparing the hardness and friction properties of the two coatings. The results showed that the pulsed irradiation purified the coating surface, formed an evaporative recondensation layer and a plastic deformation layer, and produced a dense remelting layer with a thickness of 3-4 µm. The remelted layer led to an increase in the hardness of the irradiated coating and a decrease in the friction coefficient and wear. The pulsed irradiation effectively improved the mechanical properties of the coatings.