Intense Pulsed Ion Beam Irradiation Research Articles

Study on ablation products of zinc by intense pulsed ion beam irradiation

AbstractAs a kind of flash heat source, intense pulsed ion beam (IPIB) can be used for material surface modification. The ablation effect has important influence on interaction between IPIB and material. Therefore, the understanding of ablation mechanism is of great significance to IPIB application. In this work, pure zinc targets were irradiated and ablated by IPIB. In the ablation process under the different ion beam energy densities, the ablation products were collected by a monocrystalline silicon substrate. By analyzing the ablation products with scanning electron microscope and energy-dispersive spectrometer, the surface morphology, and the spatial distribution of ablation products quantity were obtained. The results are useful for clearing the ablation process and the influence of beam parameter on the ablation effect.

Characteristics of metal ablation product by intense pulsed ion beam irradiation

Intense pulse ion beam (IPIB) has been extensively used in material surface modification. The ablation effect plays an important role in the interaction between IPIB and material. Therefore, the understanding of ablation mechanism is of great significance for IPIB application. Here, to investigate the ablation process and the characteristics of ablation products, pure zinc targets are bombarded by IPIB of 1.2-1.5 J/cm2 energy density at TEMP-4M accelerator. The ablation products are collected by monocrystalline silicon substrates in the IPIB irradiation process. By using the scanning electron microscopy, energy dispersive spectrometer and high precision balance, the surface morphology of the substrate and the characteristics of ablation products are obtained. The majority of observed ablation products are nearly circular particles with diameters of 0.03-2.00 m. There are a small number of zinc droplets and solid debris with large irregular shapes on the silicon substrate. Combining Monte Carlo method and infrared imaging diagnostic results, a heat conduction model is constructed by finite element method to describe the distribution and evolution of thermal field formed by IPIB on a zinc target. The results show that the zinc target can be melted and evaporated under a 1.2 J/cm2 IPIB irradiation. By comparing the experimental resuls with the simulation results, it is found that the gaseous, liquid and solid ablation products are generated collectively in the zinc ablation process. The causes of the different ablation products are also studied.

The ablation mass of metals by intense pulsed ion beam irradiation

Ablation effect plays an important role in the process of material modification by intense pulsed ion beam (IPIB). As a direct observable in the process of target irradiated by IPIB, the ablation mass is a crucial physical quantity for understanding the interaction between IPIB and target material. Moreover, it is critical to uncover the mechanism of ablation by IPIB. In the present work, we used IPIB provided by BIPPAB-450 accelerator at Beihang University to bombard Zn, Pb, Sn, Cu, and W targets. By measuring the ablation masses under different energy densities, the ablation thresholds of Zn and Pb have been obtained. In addition, correlations between experimental data and incident beam parameters have been investigated. The results are helpful to understand the influence of beam parameter and material properties on the ablation mass.

Distribution and evolution of thermal field formed by intense pulsed ion beam on thin metal target

Intense pulsed ion beam (IPIB) is characterized by short-pulsed high power density. With the strong thermal effect in the surface as the dominating feature, IPIB is an ideal technique for flash-heating surface processing of materials, especially for metals and alloys. Thus, the understanding of formation and evolution of thermal field induced by IPIB irradiation is of great significance to their application and diagnostic techniques. Due to the short pulsed duration and high energy flux of IPIB, the study in this field was so far mainly yield to numerical simulation. In this paper, with a combination of infrared image diagnostics, numerical analysis using Monte Carlo (MC) and finite element methods (FEM), the distribution and evolution of thermal field formed by IPIB produced by a magnetically insulated diode on a thin metal target was studied. The evolution of the thermal field and its effects on applications, such as the design of calorimeters was discussed reasonably.

Distribution and evolution of thermal field induced by intense pulsed ion beam on thin metal target

In this paper, combined with the latest development in relevant diagnostic and modeling techniques, the intense-pulsed ion beam (IPIB) energy deposition model in solid targets is established. The power density distribution induced by IPIB is simulated by Monte Carlo method on the basis of energy balance. By taking the power density as the source term, the thermal field distribution and evolution on a 100 μm stainless steel target irradiated by IPIB are simulated using the finite element method (FEM) in a time scale of several ms. Results reveal that in a time scale of several μups after IPIB irradiation, the main feature in the induced thermal field is a thermal shock within the depth of several times of the ion range. In the time scale of ms, thermal equilibrium can be established between the front and rear surfaces of the target, and the cross-sectional temperature field profile has a similar profile to the cross-sectional energy density distribution of the ion beam. This proves that by the infrared imaging diagnostic method, high resolution cross-sectional energy density diagnostics of IPIB can be achieved with a shooting time delay in ms scale.

The Irradiation Effects of Metal Gold Surface by Intense Pulsed Ion Beam

We report a modification method for Gold target by intense pulsed ion beam (IPIB) irradiation. Based on the temporal and spatial distribution models of the ion beam density detected by Faraday cup in the chamber and the ions accelerating voltage, the energy deposition of the beam ions in Au is calculated by Monte Carlo method. Taking this time-dependent nonlinear deposited energy as the source term of two-dimensional thermal conduction equation, we obtain the temporal and spatial ablation process of metal Au during a pulse time. The top-layer Gold material in thickness of about 0.25μm is ablated by vaporization and the layer in thickness of 1.40μm is melted after one shot at the ion beam density of 300 A/cm2.

EFFECT OF IRRADIATION WITH PULSED ION BEAM ON THE MICROSTRUCTURE OF TiH 2

Titanium has long been of interest as hydrogen storage material since titanium has a high affinity to hydrogen isotopes. Titanium deuteride or tritide is an important nuclear material used in the field of nuclear technology. Investigations concerning hydrogen–titanium system seem to mainly focus on the hydrogen thermal desorption spectra so as to study hydrogen desorption kinetics from metal hydride and to determine the rate–controlling step, but little is known on the evolution of its compositional changes under a much more un–equilibrium condition. In the past two decades, the intense pulsed ion beam (IPIB) technique has received extensive attention as a tool for surface modification of materials. Compared with conventional ion implantation, IPIB irradiation into materials possesses a higher energy density with shorter pulse width and be typical of more intense thermal–mechanical effect. From such a point of view, considering the features of extreme high heating and cooling rate of IPIB, IPIB as a method to evaluate the stability characteristics of titanium hydride film is utilized in order to determine a predictable behavior of the film’s evolution under an extreme un–equilibrium external condition. In current study, TiH2 films irradiated by intense pulsed ion beam have been investigated by using scanning electronic microscopy, surface profilometer, X–ray diffraction and slow positron annihilation, in order to evaluate the effect of irradiation with pulsed ion beam on the microstructure of TiH2. Three sets of TiH2 films are irradiated several shots * D} <2bj ^SG 11205136 mlL-C : 2013–03–18, ml['-C : 2013–07–20 j3 : ℄ n, , 1987 W, %e DOI: 10.3724/SP.J.1037.2013.00122 1270 p ` AE x 49 * at energy density ranging from 0.1 J/cm to 0.5 J/cm. No noticeable phenomenon of melting and change of phase structures have occurred to samples under irradiation of 0.1—0.3 J/cm. However, phenomenon of melting and indication of cracking has been detected on the surface after energy density reaches 0.5 J/cm. Besides, desorption of hydrogen from the film, and a titanium hydride with a body centered tetragonal structure (bct), seldom reported by researchers and formed under extreme conditions, has also been identified only after energy density of IPIB reaches 0.5 J/cm. S parameter of slow positron annihilation reflects that the crystal defect structures have been greatly changed by IPIB irradiation, in which S parameter reaches a large value at 0.3 J/cm with 1 shot, while a small one at 0.5 J/cm with 5 shots.

强流脉冲离子束辐照铜靶热效应数值研究

为了研究强脉冲离子束辐照改性铜靶的行为，建立了基于靶室中法拉第杯检测的离子束流密度和离子加速电压时空分布模型；采用蒙特卡罗方法计算了束流在铜靶中的能量沉积，并将这随时间变化的非线性沉积能量作为热传导方程的热源项，计算得到了脉冲期间靶材内部温度场的演化规律。一次脉冲后与液化烧蚀相比，靶材表面较小区域的物质气化烧蚀掉，辐照中心处熔化的厚度最大；气、液化烧蚀厚度随偏离中心位置而减小。当束流密度为300 A/cm2时，中心区域气化烧蚀和液化烧蚀的厚度分别达到0.2微米和1.3微米；脉冲期间热量延纵深方向的传播距离小于2微米。 A modification method for Copper target by intense pulsed ion beam (IPIB) irradiation has been reported. Based on the temporal and spatial distribution models of the ion beam density detected by Faraday cup in the chamber and the ions accelerating voltage, the energy deposition of the beam ions in Cu is calculated by Monte Carlo method. Taking this time-dependent nonlinear deposited energy as the source term of two-dimensional thermal conduction equa- tion, the temporal and spatial ablation process of metal Cu during a pulse time was obtained. Only a little area of mate- rial is ablated off due to the vaporization compared with the melting ablation area on the surface after a shot. The most deep melting depth is in the irradiation centre. The melting and vaporizing thicknesses decrease with the increasing dis- tance from the irradiation centre. The top-layer Copper material in thickness of about 0.2 μm is ablated by vaporization and the layer in thickness of 1.3 μm is melted after one shot under the ion beam density of 300 A/cm2. The thermal transportation along the longitudinal direction in the specimens is less than 2.0 μm during a pulse.

Improving anti-corrosion property of thermal barrier coatings by intense pulsed ion beam irradiation

Anticorrosion behavior is an important factor for the reliability and durability of thermal barrier coatings (TBCs). Intense pulsed ion beam (ion species: 70% H + + 30% C +; current density: 150 A/cm 2 and 250 A/cm 2; accelerate voltage: 300 kV; pulse duration: 65 ns) irradiation were used to improve the anticorrosion behavior of the Y 2O 3-stabilized ZrO 2 (YSZ) /NiCoCrAlY thermal barrier coating. The anticorrosion property of the TBCs was evaluated with polarization curves method. A quite good result was obtained. Further analysis show that IPIB irradiation can seal the pores in YSZ layer, and block the penetration channels of corrosive fluid, therefore, improves the anticorrosion behavior.

Detection of shocks generated by intense pulsed ion beam irradiation

Because the shocks induced by intense pulsed ion beam (IPIB) irradiation are responsible for long range effect, it is necessary to analyze the behavior of shocks theoretically and experimentally. But it is very difficult to find stress signals due to the 50 ns pulse duration of IPIB. In this paper, a detecting system was designed and manufactured carefully. A polyvinylidene fluoride (PVDF) film with 100 μm in thickness was selected as the piezoelectric probe in our detecting system. With this system, shocks, induced by IPIB irradiation, were caught at the backside of Al target successfully. The thicknesses of the Al samples were 1 mm and 2 mm respectively. Samples were irradiated by IPIB with different current density ranging from 250 A/cm 2 to 800 A/cm 2. Wave profiles were caught and record by oscilloscope of model TDS2024 (200 MHz, 2 Gs) and TDS3052B (500 MHz, 5 Gs). Experimental results have shown in good accordance with our theoretical calculations.

Numerical Research on Plasma Generation and Expansion into Vacuum

Energy deposition of intense pulsed ion beam (IPIB) on the Ti target based on the 2D model of IPIB density has been simulated by the Monte Carlo (MC) method. Taking the deposited energy as the thermal source, we have established the ablation model of the target and calculated the spatial and temporal evolution of the ablation shape of the Ti target irradiated by IPIB with different energy densities. We have also established the ejection model of the hydrodynamic equations related to the ablation shape of the target by using the ablation results as the initial conditions of plasma formed by IPIB irradiation. The spatially and temporally evoluted profiles of the plasma pressure and mass density are calculated.

Study of metal film/substrate mixing by intense pulsed ion beam

Intense pulsed ion beam (IPIB) irradiation may benefit from mixing more than traditional ion beam does, due to its high power density and high energy deposition density. In this work, the IPIB mixing effects of three different film/substrate combinations, Ni/Ti, Ti/Al, and Al/Ti were studied. It has been found that the mixing efficiency is obviously dependent on the difference of some thermodynamic parameters of the two components to be mixed. The best mixing layer is that with gradient component distribution formed in Ni/Ti combination by single shot IPIB irradiation. Al/Ti and Ti/Al combinations, in which the thermodynamic parameters of Al and Ti are greatly different, did not get efficient mixing as Ni/Ti combination did, although the thickness of mixing layers are all greater than 1.5 μm. The mechanisms of IPIB mixing are discussed.

Surface modification of high-speed steel by intense pulsed ion beam irradiation

The structural and phase transformations occurring in the near-surface layers of pre-quenched W 6Mo 5Cr 4V 2 high-speed steel (HSS) after intense pulsed ion beam (IPIB) irradiation, as well as their effect on the wear and corrosion resistance of irradiated samples have been investigated. The IPIB consists mainly of Cn + (30%) and H + (70%), with high beam current densities of 80–160 A/cm 2, an acceleration voltage of 250 kV and pulse duration of 70 ns. Samples were bombarded with 1, 3 and 5 pulses. Electron microscopy and X-ray diffraction revealed that after IPIB irradiation the initial martensite in the near-surface layers of HSS changed into austenite where residual stresses were produced also. Refined crystal grains in the near-surface layer with a thickness up to ∼ 2 μm were also observed. Redistribution and interlace of dislocations in the irradiated samples were generated due to the impact of the shock wave. With increasing number of pulses, liquid-phase dissolution of the M6C carbides occurred in the near-surface layer and nanocrystalline MC was produced. This process results in a decrease of martensite crystal (α-phase), an increase of the austenite (γ-phase) and dispersion of the carbides. The wear resistance of the HSS was improved by a factor of 2 due to the formation of metastable nanocrystalline phases, the presence of residual stresses and the redistribution of dislocations. Corrosion resistance of HSS was also improved after IPIB irradiation.

Propagation of Plasma Generated by Intense Pulsed Ion BeamIrradiation

Taking the calculation results based on the established two-dimensionalablation model of the intense-pulsed-ion-beam (IPIB) irradiation processas initial conditions, we build a two-dimensional hydrodynamic ejectionmodel of plasma produced by an IPIB-irradiated metal titanium targetinto ambient gas. We obtain the conclusions that shock waves generatewhen the background pressure is around 133 mTorr and also obtain theplume splitting phenomenon that has been observed in the experiments.

Nitride Formation on Titanium under Irradiation of Intense Pulsed Ion Beam

Nitriding of titanium was achieved in a vacuum of ~2×10-2 Pa by applying intense pulsed ion beam (IPIB) irradiation. Various phases including ‘pure’ nitrides (e.g. Ti2N, TiN) as well as carbonitrides (e.g. TiC0.3N0.7) were found on the IPIB-irradiated surfaces that depended on the ion beam intensity, shot number, and sample position with respect to the ion beam axis. It was found that the nitrides were preferably produced at moderate beam intensity by which the nitriding depth increased greatly with multi-shot irradiation. No or less nitrides were produced under irradiation of very high intensity or less number of shots. It is demonstrated that the IPIB nitriding process is very efficient even in vacuum where the residual N2 can readily react with melted Ti surfaces under IPIB irradiation. The origin of incorporated C in the nitrides is mainly attributed to the anode material of ion diode used in the IPIB apparatus.

Microstructure and wear resistance of high-speed steel treated with intense pulsed ion beam

The structural and phase transformations occurring in the near-surface layers of pre-quenched W 6Mo 5Cr 4V 2 high-speed steel (HSS) subjected to intense pulsed ion beam (IPIB) melting have been investigated. The effect of IPIB irradiation on wear resistance of the HSS has also been studied. The IPIB consists mainly of C n+ (70%) and H + (30%), with a high beam current density of 80 A/cm 2, acceleration voltage of 250 kV and pulse duration of 70 ns. Samples were bombarded with 1, 3 and 5 pulses. Electron microscopy and X-ray diffraction have revealed that after IPIB irradiation the initial martensite in the near-surface layer of HSS changed into austenite and residual stresses were produced. Refined crystal grains in the near-surface layer having a thickness up to ∼2 μm were also observed. Redistribution and interlace of dislocations in the irradiated samples were generated under the impact of the shock wave. With increasing number of pulses, gradual liquid-phase dissolution of the M 6C carbides occurred in the near-surface layer and produced nanocrystalline MC. This process results in the decrease of martensite crystal (α-phase) and increase of the austenite (γ-phase) content and the dispersion of carbides. The wear resistance of the HSS was improved by a factor of 2, which is explained by the formation of metastable nanocrystalline phases as well as by the presence of residual stresses and the redistribution dislocations.

A possible thermodynamic mechanism of craters formation on metal surfaces caused by intense pulsed ion beams

It was found that some craters appeared on the irradiated surfaces that have been melted under intense pulsed ion beam (IPIB) irradiation. These craters with various sizes and morphologies limit the utilization of IPIB as a novel means of surface processing in some cases. In this work we examined surfaces of 45 # steel and Ni 3Al samples irradiated with IPIB at different beam parameters with scanning electronic microscopy (SEM) and energy dispersive spectrometry (EDS), and found that the craters basically can be sorted into two groups. The first kind of craters directly relates to droplet from the ion source, and the other kind of craters is due to the non-equilibrium process of ultra fast quenching. According to the dynamic theory of interaction between ions and materials and the thermodynamic theory about defects, a possible forming mechanisms for the second kind of craters is proposed in this paper. The vacancy densities produced in IPIB irradiation at various pulse parameters are calculated. Moreover, the process of cratering is analyzed in detail, and the variety of the crater morphologies is discussed.

Modification of Graphite Surface by Intense Pulsed Ion-beam Irradiation

The highly oriented pyrolytic graphite (HOPG) targets were irradiated with 70-120 J/cm2 of pulsed ion beams. The deposited energy by the ablation plasma onto the target was 0.8 J with 100 J/cm2 of the ion beam irradiation. The fast heating and fast quenching effects occurred on the target surfaces, and these effects can be enhanced at the higher energy density of beam irradiation. In the SEM analysis, sphere particles and whiskers which approximately 1 μm in diameter were observed on the irradiated surface. These whiskers may have been grown under the hydraulic pressure by the ablation plasma radiation.

Nanocrystallization of Pure Titanium Surface by Intense Pulsed Ion Beam Irradiation

A hydrogen intense pulsed ion beam (IPIB) with an ion energy of 180 keV, ion current density of 460 A/cm2, and pulse duration of 65 ns was irradiated on a pure titanium surface. A rapid heating and cooling treatment due to irradiation of the IPIB led to the formation of a nanocrystalline structure with the average grain size of 32 nm. The reduction in grain size resulted in the improvement of hardness and tribological property of the sample. The IPIB-irradiated Ti is 1.3 times harder than the non-irradiated one. The friction coefficient of pure Ti was reduced from 0.6 to 0.1 by IPIB-irradiation, and the IPIB-irradiated Ti maintained the low friction coefficient till 200 wear cycles. The calculated cooling rate of the IPIB-irradiated Ti, 3.0 ×107 K/s in the present experiment, is sufficiently high to form a nanocrystalline structure.

Defects in α-Fe induced by intense-pulsed ion beam (IPIB)

Using Rutherford back-scattering (RBS), secondary ion mass spectrometry (SIMS), Auger-electron spectroscopy (AES), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques, formation of different point and linear defects have been found in iron as a result of intense pulsed-ion beam (IPIB) treatment. The close correlation between an average scalar dislocation density with a microhardness magnitude has been proved both in near-surface layers and at large depths. The comparable analysis of structure-phase damage after IPIB and intense pulsed-electron beam irradiation is interesting for an explanation of different modified properties and an application of such treatments in technologies.