High-current Pulsed Electron Beam Irradiation Research Articles

Surface modification of Al-15Al2O3-0.3G powder metallurgical alloy induced by high-current pulsed electron beam

This paper investigates the effect of high-current pulsed electron beam (HCPEB) surface treatment with two, five, and eight pulses on Al-15Al2O3-0.3G prepared by powder metallurgy. The results show that the presence of graphene during HCPEB irradiation effectively controls the extension of microcracks. The surface hardness of the samples increased by 66.56% and the wear rate decreased by 68.98% after eight-pulse HCPEB treatment. The increase in hardness is attributed to the uniform dispersion of hard particles, fine grain strengthening, dislocation strengthening, and amorphous structure formation by XRD, SEM, and TEM analysis during HCPEB irradiation. The improvement in wear resistance was attributed to the increase in hardness. The corrosion current density in 5 wt. % NaCl solution decreased from 1.212 × 10−4 to 3.353 × 10−5 after eight-pulse HCPEB treatment; the improved corrosion resistance performance is attributed to the equilibrium structure induced by HCPEB treatment.

The refined microstructure and enhanced properties of the Al-Mo laser-alloyed layer after high-current pulsed electron beam irradiation

The aim of this study is to investigate the microstructure and properties of the AlMo laser-alloyed layer induced by high-current pulsed electron beam (HCPEB) irradiation. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were utilized to investigate the microstructures of the modified layer. The microhardness and friction properties were also measured. The microstructural observation shows that HCPEB irradiation led to the formation of a modified layer approximately a dozen microns thick, which was the absence of the pores. It was found that the flower- and strip-like AlMo particles were dissolved to form nano-size particles consisting of Al5Mo (h2), Al12Mo, and Al17Mo4 phase after HCPEB irradiation. Additionally, the slip bands and high-density dislocations were formed in the modified layer. The refined microstructure significantly enhanced the microhardness of the laser-alloyed layer. A quantitative evaluation was conducted to investigate the individual contributions of four strengthening mechanisms to the strength of the modified layer, which indicated that dislocation and grain boundary strengthening were dominant. The results of sliding wear tests show that the modified layer exhibited superior properties compared to the laser alloying layer, which was attributed to the formation of crystal defects, solid solutions, and nanoparticles.

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.

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.

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.

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.

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.

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.

Influence of high-current pulsed electron beam irradiation on element diffusion behavior and mechanical properties of TC4/304 stainless steel diffusion bonded joints

Influence of high-current pulsed electron beam irradiation on element diffusion behavior and mechanical properties of TC4/304 stainless steel diffusion bonded joints

Microstructure and mechanical properties of NiCoCrAlY laser cladding coating after high-current pulsed electron beam irradiation

ABSTRACTSurface modification of laser cladding coating NiCoCrAlY was carried out by high-current pulsed electron beam irradiation. The microstructure of the NiCoCrAlY coating after irradiation was studied by XRD and SEM. The results showed that the NiCoCrAlY cladding layer displays slip and a nanocrystalline structure following high-current pulsed electron beam irradiation. The high-density slip structure affects the residual stress on the surface of the melted coating, resulting in a change of the phase structure. The mechanical properties of the NiCoCrAlY coating were studied using a Vickers micro-hardness tester and a straight-line-reciprocating dry sliding wear tester. The results showed the average microhardness of the melted coating increased by 9%, and the average wear coefficient decreased by 33.7% after five electron beam irradiations.

Evolution of morphology, microstructure and phase composition of zirconia thin coating on copper as a result of low energy high current pulsed electron beam irradiation

Using X-ray diffraction, scanning and transmission electron microscopy we studied the evolution of the morphology, microstructure and phase composition in the near-surface layer of copper covered with thin (2.8 μm) ZrO2 coating induced by low-energy high-current pulsed electron beam irradiation (the surface energy density was in the interval of 5.0–18.0 J/cm2, the accelerating voltage was 30 kV, the pulse duration was 3.2 μs, the number of pulses was 10). The variation of adhesion of the coating to substrate was evaluated using scratch testing. The evaporation of the upper part of the coating during irradiation was found and the thickness of the coating nonlinearly decreased with the increase of the energy density. We discussed the reasons for the surface cracking taking into account microstructural changes in the near-surface layer of the material. The irradiation was found to transfer most of monoclinic ZrO2 phase in the as-deposited coating to tetragonal and, possibly, cubic one. The factors influencing the adhesive strength of the coating were revealed and a potential for the increase of adhesion was demonstrated. We showed that irradiation with enhanced surface energy density was required to obtain copper-based composite hardened with zirconia nanoparticles in the near-surface layer. The thickness of the composite layer may be as much as 6 μm.

Effects of WC grain size on surface hardening of WC-10Co cemented carbides by pulsed electron beam irradiation

Effects of primary WC size (DWC) in the surface enhancing of WC-Co cemented carbides by high current pulsed electron beam irradiation (HCPEBI) were studied in this work by investigating the morphological/microstructural evolution, phase transformations and the variation of microhardness of samples (Co: 10 wt %, DWC: ∼1.27 μm, ∼0.87 μm and ∼0.42 μm) treated with a range of HCPEBI shots under the energy density of 6 J/cm2. Results showed, with accumulating HCPEBI, the surface roughness of coarse-grained samples increased more significantly. The effects of DWC were more prominent in phase transformation and microstructure change under lesser irradiation. For samples with larger DWC, although the decomposition rate of WC in the top surface region was the lower, the amount of graphite precipitates prevailed overall. The maximum microhardness was also found in the irradiated coarse-grained (DWC = ∼1.27 μm) samples 3128.5 HV, showing a ∼80% increase from the initial state ∼1735.8 HV. Whereas for the fine-grained samples, surface microhardness gained a mere ∼29% increase after 35 shots.

Influence of high-current pulsed electron beam irradiation on elemental diffusion and mechanical properties of copper/316L stainless-steel bonded joints

In this paper, Cu and 316L stainless steel with abundant crystal defects are constructed on bonding surfaces using high-current pulsed electron beam (HCPEB), and direct bonding is carried out in vacuum. The bonding temperature was varied as 800 °C and 850 °C, while the bonding pressure of 5 MPa and the bonding time of 40 min was maintained. Microstructure observations revealed that the initial coarse grains of the 316L was significantly changed to fine grains with abundant crystal defects after HCPEB irradiation. After diffusion bonding, the bonded area of the initial joint is not completely joined. Comparatively, the joints pretreated by HCPEB displayed a well-bonded interface. The diffusion coefficient of Cu at interface is significantly increased as well, which is attributed to the acceleration of atomic diffusion. Bonding strength indicates that the shear strength of the joints prepared via HCPEB pretreatment is much higher than the initial joints.

Microstructure and properties of mono-crystalline germanium enhanced by high-current pulsed electron beam

High current pulsed electron beam (HCPEB) technology was applied to irradiate the surface of mono-crystalline Ge wafers (Ge (100) and Ge (111)) with different orientations, and the microstructure and properties of the irradiated surface were analyzed in detail. The results show that after HCPEB irradiation, numerous molten pits and local microcracks were produced on the surface of mono-crystalline Ge, and the pit density decreased with the increase of irradiation pulses. TEM observations indicated that after irradiation, the defects are mainly vacancy group defects and dislocation rings, and Ge nanocrystals with uniform size distribution are produced. HCPEB irradiation also formed self-assembled nanostructures on the surface of Ge. Cross section TEM indicated that the 250 nm deep defect channels were under the quantum dots, which confirms the formation mechanism of self-assembled nanostructures. The photoluminescence results indicated that the irradiated mono-crystalline Ge still has blue emission properties, and the luminescence mechanism is the quantum confinement effect of Ge nanocrystals embedded in slightly oxidized or nitrided amorphous structures.

Comparative hot corrosion performance of arc ion plated NiCoCrAlYSiHf coating in Na2SO4/NaCl/V2O5-media via high-current pulsed electron beam

The surface of NiCoCrAlYSiHf coating was modified by high-current pulsed electron beam (HCPEB), and the hot corrosion behavior of the coatings in different salts of Na2SO4/K2SO4, Na2SO4/NaCl, and Na2SO4/V2O5 at 900 °C was studied. Microstructural results show that after HCPEB irradiation, the surface of coating was remelted, and a polished, purified, compact, and refined remelted layer was formed; a large number of Y-enriched nanoparticles and high-density dislocation entanglement structures were uniformly distributed in the remelted layer. The results of the hot corrosion test show that the irradiated effects promoted the formation of a continuous and dense protective oxide film in different molten salt environments, effectively prevented the hot corrosion damage of the coating. This significantly reduces the corrosion weight gain, and reduced the corrosion rate by about one order of magnitude compared with the original ones. HCPEB technology significantly improves the hot corrosion resistance of NiCoCrAlYSiHf coating.