Energy Density Of Electron Beam Research Articles

Analysis of contact zone of coating-substrate system exposed to irradiation with a pulse electron beam

Using the wire-arc additive manufacturing method (WAAM) on a 5083 aluminum alloy substrate, a non-equiatomic Mn – Cr – Fe – Co – Ni high-entropy alloy (HEA) coating was formed. By scanning and transmission electron diffraction microscopy we analyzed the structure, phase and elemental composition of the contact zone after irradiation with high-current low-energy electron beams with the following parameters: accelerated electron energy 18 keV, electron beam energy density 30 J/cm2, electron beam pulse duration 200 µs, number of pulses 3, pulse repetition rate 0.3 s–1. Multiphase multielement submicro- and nanocrystalline structures are formed predominantly in the substrate, which has a lower melting temperature compared to HEAs. Mutual doping of the coating – substrate system occurs in the contact layer, which has sinuous boundaries. The contact layers adjacent to the substrate and coating have the structure of high-speed cellular crystallization. In the layer adjacent to the substrate, the cells are formed by a solid solution of magnesium in aluminum. Interlayers of the second phase, enriched in atoms of the coating and substrate, are revealed along the cell boundaries. In the layer adjacent to the coating, the cells are formed by an alloy of composition 0.17Mg – 20.3Al – 4.3Cr – 16.7Fe – 9.3Co – 49.2Ni corresponding to the coating. Interlayers of the second phase, enriched mainly in magnesium and, to a lesser extent, in atoms of the HEA coating, are located along the cell boundaries. Central region of the contact zone with a thickness of ~1700 μm is formed by lamellar crystallites, which indicates the eutectic nature of its formation. Its main element is aluminum (≈77 at. %).

Electron-ion-plasma surface modification of hypereutectic silumin

In this study, an integrated treatment approach was employed to modify hypereutectic silumin. This method involved electroexplosive alloying of the surface layer with yttrium oxide powder, followed by irradiation with a pulsed electron beam. The experimental data obtained demonstrate that this integrated treatment results in the formation of a submicron-nanocrystalline structure characterized by high-speed cellular crystallization of aluminum within the surface layer. This structure is composed of crystallization cells enriched with aluminum atoms, indicating the creation of a solid solution based on aluminum. The nanocrystalline layers, formed by silicon particles and yttrium oxide, are positioned at the cell boundaries. The study reveals that, as a consequence of integrated treatment with an electron beam energy density of 25 J/cm2 , the wear parameter of the modified samples increases by 7.9±0.6-fold, and the friction coefficient decreases by 1.7±0.15-fold compared to the initial state. Additionally, the microhardness of the modified silumin surface layer increases by 1.5±0.12-fold compared to the initial state. When the electron beam energy density is elevated to 35 J/cm2, the wear parameter of silumin is enhanced by 2.1±0.21-fold, while the friction coefficient increases by 1.13±0.1-fold. However, the microhardness decreases by 1.3±0.13-fold, while still surpassing the specified characteristics of untreated silumin. This investigation postulates that the substantial increase in the wear parameter during integrated treatment may be attributed to the presence of silicon inclusions in the surface layer that did not dissolve during the modification process. These inclusions are surrounded by the high-speed cellular crystallization structure mentioned earlier.

High-precision reconstruction of the heat flux field by a scanning electron beam for thermal assessment of a hypersonic vehicle

The development of thermal assessment technologies for materials and structures is crucial to the security assessment of hypersonic vehicles. High-precision reconstruction of a high heat flux field with a high energy conversion efficiency is the ultimate development goal of thermal assessment technology. A novel thermal assessment method based on a scanning electron beam is proposed. Corresponding thermal assessment equipment is constructed. A nonuniform heat flux field with a peak heat flux of 2.58 MW/m2 is precisely reconstructed by this equipment with an energy conversion efficiency of 58%. As a reference, the stagnation point heat flux of the return cabin of Apollo 6 during reentry is 2.4 MW/m2. Referring to the electron beam energy density (10,000 MW/m2), this thermal assessment method has the potential to meet the maximum thermal assessment requirement (600 MW/m2) of hypersonic vehicles. This method is expected to promote the thermal assessment of hypersonic vehicles into a new era.

Research on the Induced Electrostatic Discharge of Solar Arrays under the Action of ESD EMP

In this paper, the electrostatic discharge of solar arrays in spacecraft energy systems is taken as the research object. The influence and internal mechanism of external electromagnetic radiation on electrostatic discharge is studied. Meanwhile, the charging and discharging test platform of spacecraft solar arrays under a strong field is first established. Then, the influence of irradiation field strength, electron beam energy and beam density on electrostatic discharge of solar arrays is analyzed and summarized. The results show that during the irradiation process of solar arrays using a high-energy electron beam under vacuum conditions, the higher the electron beam energy and the beam current density, the higher the discharge frequency of the solar array. When the intensity of the external electromagnetic radiation field increases, the discharge frequency also increases. Under the action of external radiation field with the same peak field strength, the larger the gap, the smaller the discharge frequency. With the increase in the field strength, the potential difference of each part of the solar array becomes smaller, and the peak of the discharge current decreases. The research results can provide technical reference for electrostatic protection of spacecraft solar arrays.

Control of mechanical properties of a high-entropy alloy Cantor CoCrFeMnNi

A brief analysis of the work on changing the mechanical properties of the high-energy alloy (HEA) Cantor CoCrFeMnNi in various ways has been performed. The article describes the influence of alloying with aluminum, vanadium, manganese, titanium, silicon, carbon, copper on the hardening of wind turbines obtained by vacuum arc melting, laser melting, arc melting and drip casting, mechanical alloying with subsequent plasma sintering, gas sputtering followed by shock wave and static compaction. It is shown that additives of 2.5 % TiC and 5 % WC significantly improve the tensile strength, but reduce the elongation to failure. The effect of grain size in the range of 4.4 – 155 µm is to increase the tensile strength with a decrease in grain size. Lowering the temperature increases the strength and yield limits for grains of all sizes. Intensive plastic deformation forming nanoscale (~50 nm) grains significantly increases the tensile strength up to 1950 MPa and hardness up to 520 HV. Subsequent isochronous and isothermal annealing allows varying the strength and ductility of wind turbines. The formation of nanostructured-phase states during shock compounding, mechanical alloying and subsequent spark plasma formation significantly increase the tensile strength at room temperature, maintaining excellent plasticity (elongation of approximately 28 %). As one of the methods of modifying the mechanical properties of wind turbines, the authors propose electron-beam processing (EPO). The analysis of the deformation curves of the wind turbine, obtained by the technology of wire-arc additive production, after EPO with an electron beam energy density of 10 – 30 J/cm2, has been carried out; assumptions about the reasons for the decrease in strength and ductility characteristics have been found and substantiated. A comparative analysis of mechanical properties of the Cantor wind turbine obtained by various methods was carried out, and the reasons for discrepancy in the values of strength and plastic parameters were noted.

Structure and properties of the CrMnFeCoNi high-entropy alloy irradiated with a pulsed electron beam

According to the technology of wire-arc additive manufacturing a nonequiatomic composition CoCrFeMnNi high-entropy alloy (HEA) was obtained. Deformation curves of samples in tension are plotted and analyzed after the HEA fabrication by the methods of wire-arc additive manufacturing (initial state) and after the electron-beam processing (EBP). The EBP results in a decrease in the HEA's strength and plastic properties. Along with a pit character of the fracture a presence of micropores and microlayerings are identified. A study of the HEA's fracture surface after the EBP except for regions with a ductile fracture mechanism revealed regions with a band (lamellar) structure. The area with a band structure increases with a growth in the beam electron density from 25% at 10 J/cm2 to 65% at 30 J/cm2. A diameter of separation pits in fracture bands varies in the limits (0.1–0.2) μm, which is considerably less than those of the remaining part of the HEA sample. An average size of crystallization cells formed in the EBP depends on the energy density of electron beam and increases from 310 nm at 15 J/cm2 to 800 nm at 30 J/cm2. A non-monotonous change in the scalar dislocation density, reaching a maximum value of ∼5.5 · 1010 cm-2 at a distance of 25 μm from the irradiation surface is revealed. It is suggested that defects being formed in surface layers in the EBP may be one of the reasons for decreasing the values of HEA strength and plasticity.

Fractography of fracture surface of CrMnFeCoNi high-entropy alloy after electron-beam processing

In the past decade the attention of scientists in the field of physical materials science is attracted to studying the high-entropy alloys. By the technology of wire-arc additive manufacturing (WAAM) a high-entropy alloy (HEA) of a nonequiatomic composition was obtained. Deformation curves obtained under uniaxial tension at a rate of 1.2 mm/min at room temperature using Instron 3369 unit were analyzed in two states: initial/after fabrication and after electron-beam treatment (EBT). EBT was conducted to detect its influence on structural-phase states and mechanical properties. The EBP leads to a decrease in strength and plastic properties of the HEA. By means of scanning electron microscope LEO EVO 50, analysis of structure of fracture surface and the near-surface zone was performed. Dependences of the ultimate strength and relative elongation to failure on EBT parameters were revealed, and it was shown that values of strength and plasticity decrease nonmonotonically with an increase in electron beam energy density in the range ES = 10 – 30 J/cm2 at constant values of duration, frequency, and number of pulses. Along with a pit character of the fracture a presence of micropores and microlayering was detected. Investigation of the HEA’s fracture surface after EBP except for areas with a ductile fracture mechanism revealed the regions with a band (lamellar) structure. At ES = 10 J/cm2, the area of such structure is 25 %; it increases nonmonotonically to 65 % at ES = 30 J/cm2. The diameter of pits of detachment in fracture bands varies in the limits of 0.1 – 0.2 μm, which is considerably less than that in the remainder of the HEA samples. After EBP the thickness of the molten layer varies in the limits of 0.8 – 5.0 μm and grows with an increase in the energy density of electron beam. EBT leads to generation of crystallization cells, the sizes of which change within the range 310 – 800 nm as ES increases from 15 to 30 J/cm2. It is suggested that the defects being formed in surface layers in ЕВР may be the reason for decreasing the HEA’s maximum values of strength and plasticity.

Study on Smoothing of Hole Wall Surface by Electron Beam Polishing under Control of Magnetic Field

A surface finishing method by large-area electron beam (EB) irradiation called EB polishing has been developed recently. Highly efficient surface smoothing of mold steels with planar shape can be performed by the EB polishing. However, it is difficult to smooth wall and bottom surfaces in hole shape by the EB polishing, since the EB tends to concentrate on entrance edge or upper inside wall of hole, and the energy density of EB on the wall and bottom surface of hole may decrease. Our previous study showed that the bottom surface could be smoothed by EB polishing under control of magnetic field around the workpiece. It is highly expected that EB can be also guided to the whole area of hole wall surface under appropriate control of magnetic field there.In this study, smoothing of hole wall surface by EB polishing under control of magnetic field around the workpiece was proposed. As a basic study for smoothing of hole wall surface, L-shaped workpiece was prepared by combining two stainless steel plates, and magnet was set under the workpiece. The electromagnetic field analysis results suggested that EB could be guided to the whole area of side surface by setting magnet under appropriate setting position, since magnetic force lines are uniformly distributed on whole area of side surface. In addition, magnetic flux destiny on the side surface more increases by setting a yoke made of steel on the magnet. The experimental results show that smoothed area with the surface roughness of less than 1.5μmRz can be obtained on the whole area of side surface. Therefore, the whole area of side surface can be uniformly smoothed by guiding the EB to the side surface under appropriate control of magnetic field.

Controllable fabrication of hollow In2O3 nanoparticles by electron beam irradiation.

A growth strategy is presented for controllable fabrication of hollow In2O3 nanoparticles (NPs) via oxidation of In nanocrystals under electron beam irradiation. The morphology of the NPs can be tailored by changing the electron beam energy and current density. Yolk-shell NPs are preferentially formed under 200 keV electron beam irradiation, while hollow NPs are preferentially formed at 300 keV. This work confirms that electron beam irradiation is a valuable method for the engineering and modification of nanomaterials.

Люминесцентный контроль светодиодных гетероструктур, выращенных методом металлоорганической газофазной эпитаксии на сапфире

The paper presents the results of spectral and cardinal characteristics of AlGaN/GaN and InGaN/GaN LED heterostructure pulsed cathodes and photoluminescence grown on sapphire by metal organic vapor phase epitaxy are introduced. The effects of high current electron beam energy density on the luminescence spectra and amplitude characteristics of heterostructures are studied. The spatial distribution of fluorescence characteristics on the wafer surface was studied. It is found that in InGaN/GaN heterostructures, the maxim shifts of stimulated cathodoluminescence spectra measured at different points of the sample. This result is due to the changes in the composition and thickness of the quantum dimensional active region, and this change is not due to the ideality of the plate growth process.

Structural phase variations in high-entropy alloy at irradiation by pulsed electron beam

The high-entropy alloy (HEA) of Al - Co - Cr - Fe - Ni system of nonequiatomic composition is obtained by the technology of wire-arc additive manufacturing (WAAM) in atmosphere of pure nitrogen. By the methods of modern physical materials science it is shown that in the initial state the alloy has dendritic structure indicating nonhomogeneous distribution of alloying elements. It is a multiphase material whose main phases are Al3NCr3C2 , (Ni, Co)3Al4 . Nonadimensional particles (Ni, Co)3Al4 of cubic shape are located along interfaces of submicron phases Al3Ni and Cr3C2 . The HEA irradiation by pulsed electron beams with energy density Es = 10 + 30 J/cm2, pulse duration of 50 is, frequency of 3 Hz and pulse number of 3 leads to high-velocity melting and subsequent crystallization of surface layer. If Es = 10 J/cm2, no failure of dendritic crystallization structure happens. Interdendritic spaces are enriched in chemical elements Al, Ni and Fe, and dendrites themselves - in chromium atoms. The most liquating element of the alloy is Al, the least one is Co. If Es = 20 J/cm2, a nanocrystalline structure is formed in the layer 15 inn thick in bulk of grains. Size of crystallization cells amounts to 100 - 200 nm, size of inclusions in cell junctions is 20 - 25 nm, and along cell boundaries it is 10 - 15 nm. Cells of high-velocity crystallization are enriched in Al and Ni. The Co atoms are homogeneously distributed along the surface layer volume. The most liquating element is Cr, the least liquating one is Co. The increase in energy density of electron beam to 30 J/cm2 doesn't lead to substantial (as compared to Es = 20 J/cm2 ) variations in surface layer structure. The irradiation mode (Es = 20 J/cm2, 50 is, 3 pulses, 0.3 Hz) is detected that allows formation of the surface layer with the highest level of homogeneity of chemical element distribution in the alloy.

Increase of alloys functional properties by electronic beam processing

The article considers a review of domestic and foreign works on the use of intense pulsed electron beams for surface treatment of metals, alloys, cermet and ceramic materials. The advantages of using electron pulsed beams over laser beams, plasma flows, and ion beams are noted. The promising directions of using electron-beam processing were analyzed and are as following: 1 – smoothing the surface, getting rid of surface microcracks, while simultaneously changing the structural-phase state of the surface layer, to create high-performance technologies for the finishing processing of critical metal products of complex shape made of titanium alloy Ti-6Al-4V and titanium; steels of various classes; hard alloy WC – 10 wt. % Сo; aluminum; 2 – removal of microbursts formed during the manufacture of precision molds (SKD11 steel) and biomedical products (Ti-6Al-4V alloy); 3 – finishing the surface of molds and dies; 4 – improvement of the functional properties of metallic biomaterials: stainless steel, titanium and its alloys, alloys based on titanium nickelide with shape memory effect, and magnesium alloys; 5 – processing of medical devices and implants; 6 – formation of the surface alloys for powerful electrodynamic systems; 7 – improvement of the characteristics of aircraft engine and compressor blades; 8 – formation of thermal barrier coatings applied to the surface of the combustion chambers. It is shown that with the correct choice of process parameters, such as accelerating voltage, energy density of electron beam, number of pulses, and pulse duration, it is possible to control carefully and/or manipulate the characteristics of structural-phase state and surface properties. In order to improve the properties of the material and the durability of the products made of it, an important factor is the structure modification to form a submicro-nanosized grain (or subgrain structure).

Regularities of structure and properties modification of the steel surface layer as a result of high-cycle high-speed melting of the “film (Si + Nb) / (steel) substrate” system by an intense pulsed electron beam

Surface alloying is a promising method for improving the service characteristics of machine parts and mechanisms. The aim of this work is to analyze the patterns of evolution of the elemental and phase composition, the state of the defect substructure of the surface layer of carbon steel subjected to multi-cycle treatment (the number of cycles was varied from 1 to 5), which combines the formation of a film / substrate system and irradiation with an intense pulsed electron beam. Silicon and niobium are used as alloying elements. It has been established that irradiation of the system “film (Si + Nb) / (steel 5135) substrate” at an electron beam energy density of 20 J / cm2 leads to the formation of a multiphase high-speed cellular crystallization structure in the surface layer. The size of the crystallization cells varies from 180 nm to 520 nm, reaching the maximum size after 3 cycles of deposition-irradiation. The surface layer of steel is quenched during processing to form a martensitic structure. It was found that the Nb5Si3 is the hardening phase of the modified layer, the maximum amount of what (up to 9 wt%) was revealed after three processing cycles. It is shown that the maximum hardness of the surface layer of modified steel 5135, equal to 9300 MPa (3.2 times higher than the hardness of steel 5135 in the initial state), is achieved after 3 cycles of deposition / irradiation. The wear resistance of steel at this processing mode increases more than 90 times. It has been suggested that the hardening of steel surface layer is due to the formation of a quenched structure and the release of niobium silicide particles.

Structural Changes in the Surface of AK5M2 Alloy under the Influence of an Intense Pulsed Electron Beam

The surface of AK5M2 (Al–Si) alloy is treated with an intense pulsed electron beam in various modes (accelerated electron energy of 17 keV, electron-beam energy density of 10, 20, 30, 40 and 50 J/cm2, pulse duration of 50 and 200 μs, the number of pulses 3, and the pulse repetition rate 0.3 s–1). Microhardness analysis is performed, and the elemental and phase composition and state of the defect substructure of the surface layer are studied by scanning electron microscopy and X-ray phase analysis. It is shown that the increase in microhardness of the Al-Si alloy is due to the formation of a submicrometer-sized structure of high-speed cellular crystallization, the enrichment of an aluminum-based solid solution with alloying and impurity elements, and the reprecipitation of nanoscale particles of strengthening phases. It is suggested that the higher values of the microhardness found in the alloy irradiated at 50 J/cm2 and 50 μs compared with the alloy irradiated at 50 J/cm2 and 200 μs are due to the process of tempering the material, which have a greater development with a longer duration of exposure to beam electrons per pulse.

Liquid-phase boriding of high-chromium steel

Using the methods of modern physical materials science, structuralphase states and tribological properties of 12Kh18N10T steel, subjected to electroexplosive alloying with titanium and boron and subsequent electron-beam processing in various modes depending on electron beam energy density, exposure pulse duration and their quantity have been analyzed. It has been established that electroexplosive alloying of steel with titanium and boron leads to formation of surface layer with multiphase submicro-nanocrystalline structure, characterized by presence of micropores, microcracks, and microcraters. Complex processing, combining electroexplosive alloying and subsequent irradiation with high-intensity pulsed electron beam, leads to formation of 60 μm thick multiphase submicro-nanocrystalline surface layer. It is shown that phase composition of surface layer of steel is determined by mass ratio of titanium and boron during electroexplosive alloying. Microhardness of modified layer is defined by relative mass fraction of titanium borides in surface layer and can be more than 18 times higher than microhardness of steel in its initial state (before electroexplosive alloying). Modes of complex processing have been determined at which surface layer containing exclusively titanium borides and intermetallic compounds based on titanium and iron is formed. The maximum (approximately 82 % by weight) titanium boride content is observed when steel is processed at regime with the highest mass of boron powder in the sample (mB = 87.5 mg; mTi /mB = 5.202). With decrease in mass of boron powder, relative content of borides in surface layer of steel decreases. It was found that integrated processing of steel is accompanied by sevenfold increase in microhardness of surface layer, wear resistance of steel increases by more than nine times.

Dust mitigation technology for lunar exploration utilizing an electron beam

Dust mobilized on the lunar surface due to natural processes and/or human activities can readily stick to spacesuits, optical devices, and mechanical components, for example. This may lead to dust hazards that have been considered as one of the technical challenges for future lunar exploration. Several dust mitigation technologies have been investigated over the past years. Here we present a new method utilizing an electron beam to shed dust off of surfaces. Recent studies on electrostatic dust lofting have shown that the emission and absorption of secondary electrons or photoelectrons inside microcavities forming between dust particles can cause the buildup of substantial negative charges on the surrounding particles. The subsequent repulsive forces between these particles can cause their release from the surface. Fine-sized lunar simulant particles (JSC-1A, <25 μm in diameter) are used in our experiments. The cleaning performance is tested against the electron beam energy and current density, the surface material, as well as thickness of the initial dust layer. It is shown that the overall cleanliness can reach 75–85% on the timescale of ~100 s with the optimized electron beam parameters (~230 eV and minimum current density between 1.5 and 3 μA/cm2), depending on the thickness of the initial dust layer. The maximum cleanliness is found to be similar between a spacesuit sample and a glass surface. Future work will be focused on removal of the last layer of dust particles and an alternative method using ultraviolet (UV) light.

Changes in surface structure and mechanical characteristics of Al–5 wt%Si alloy after irradiation by electron beam

The modification of Al–5 wt%Si alloy surface by electron beam in the regimes being different in the energy density of electron beam (10, 20, 30, 40 and 50 J/cm2) and the pulse duration (50 and 200 μs) was performed in the research. It was established that the maximum increase in microhardness was observed at electron beam parameters of 30 J/cm2, 200 μs and 50 J/cm2, 50 μs; and microhardness values for each regime amounted to 860 MPa and 950 MPa, respectively. The microhardness value of the cast alloy equals to 520 MPa. The irradiation surface morphology at beam parameters of 30 J/cm2, 200 μs is characterised by numerous micropores and microcracks. The irradiation regime of 50 J/cm2, 50 μs leads to complete dissolution of intermetallide and silicon particles in surface layer; the crack density per unit of sample surface decreases in comparison with the regime of 30 J/cm2, 200 μs. The surface layer is characterised by the high-speed cellular crystallization structure with dimensions from 500 to 800 nm formed in grain volume that may be the reason for the increase in strength properties of the material.

Pulsed X-Ray and Cathodoluminescence of Pure and Alloyed Zinc Selenide Single Crystals

The paper studies the amplitude and spectral-kinetic behavior of pulsed X-ray and cathodoluminescence of non-alloyed zinc selenide (ZnSe) single crystals and those alloyed by gallium, tellurium and samarium. At 300 K, the spectra of pulsed cathodoluminescence of pure ZnSe single crystals show a 490 nm illumination at ~20 ns pulse time. Two spectral bands are observed in alloyed ZnSe single crystals, band edge at ~477 nm and with maximum at ~600 nm at a pulse time of ~20 ns and ~5 μs, respectively. The intensity ratio of these peaks depends on the electron-beam energy density and the geometry of spectrum measurements. X-ray luminescence spectra of the alloyed ZnSe single crystals show an ~600 nm illumination, the intensity of which depends on the type of impurity. The possibility of applying the pure and alloyed ZnSe single crystals is discussed herein for the development of amplitude-time characteristic sensors of electron beams and X-ray radiation energy ranging from tens to hundreds of kiloelectronvolts.

Modification of Al-10Si-2Cu alloy surface by intensive pulsed electron beam

The study reports on the electron-beam processing (energy of accelerated electrons 17keV, electron beam energy density ES=10, 20, 30, 40, and 50J/cm2, pulse duration 50 and 200μs) 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=10J/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=30–50J/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.

Clarification of Temperature Distribution for Metals with Different Thermal Conductivity in Large-area Electron Beam Irradiation

High energy density of electron beam (EB) with diameter of about 60 mm is obtained in a large-area EB irradiation method. This method can be used for melting and evaporating material surface instantly, and highly efficient surface finishing of metals such as mold steels and biomaterials is possible. Furthermore, surface functions such as corrosion resistance, water repellency and wear resistance can be improved since a thin modified layer with fine microstructure is formed on the EB irradiated surface. It is expected that thick modified layer is effective to maintain their surface functions for long-term. However, the material surface is slightly removed in formation of modified layer. Therefore, control and prediction of removal and modified layer thickness are important in order to obtain appropriate modified layer thickness and to keep the shape accuracy for metals with different thermal properties. In order to predict the removal and modified layer thickness, it is necessary to clarify the temperature distribution in depth direction and its time variation in large-area EB irradiation. In this study, changes of removal and modified layer thickness on metal workpiece with different thermal conductivity are investigated by calculation of temperature distribution in large-area EB irradiation. It is made clear that the modified layer thickness of workpiece with low thermal conductivity is larger than that with high one, while the removal layer thickness is almost the same regardless of thermal conductivity. Furthermore, analytical removal and modified layer thickness obtained by our unsteady heat conduction analysis agree well with the experimental ones. Therefore, our unsteady heat conduction analysis model has high accuracy, and it is possible to predict variations of removal and modified layer thickness on workpiece with different thermal conductivity.