Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

1. IntroductionTi6A14V alloys have been widely applied in various fields from aircraft components, chemical prrycessing facilities to medical implants, because of itsremarkable mechanical and chemical properties suchas high strength--toweight ratio and corrosion resistance [l]. Hoal.ever, its poor hardness and inferior wearing-resistance make the applicable scope ofthis material limited [2,31. There are a few reportson the effects of nitrogen ion implantation on hardness: wearing resistance, …     

Temperature elevated N ion implantation of Ti6Al4V alloys using the plasma source

Specimens of Ti6Al4V alloy were implanted with nitrogen ions of 4× 1018 cm-2 at temperatures from 100 to 600℃. Auger Electron Spectroscopy (AES), microhardness measurements and pin-on-disk wear testing, Scanning Electron Mi croscopy (SEM), and Glancing angle X-ray Diffraction (XRD) were utilized to evaluate the surface property improvements. The thickness of implanted layers increased by about an order of magnitude when the temperature was elevated from 100 to 600℃. Higher surface hardness and wear resistance were also obtained in the high tempera ture implantation. The XRD image showed the presence of nitrides of titanium at the implanted surface.     

中国散裂中子源靶体研制

中国散裂中子源(CSNS)靶体选用钨为靶材、钽为包覆层,采用包套法结合热等静压扩散焊工艺制备了钽包覆钨靶片。经检测,钨钽界面结合良好,钽层与钨基体平均结合强度大于64.07 MPa。靶体将钨靶片分成厚度不等的11片,散热采用一进一出的并行流结构,利用CFD软件进行了模拟计算,钨靶片间冷却流道间隙为1.2 mm,100 kW满功率运行情况下靶体最高温度为182.3 ℃,冷却水温升为7.1 ℃。经过半年多的试运行,CSNS靶体各参数满足CSNS的要求。     

The range distribution and annealing behavior of Er ions implanted in silicon-on-insulator

The range distribution for energetic 400 keV Er ions implanted in silicon-on-insulator (SOI) at room temperature were measured by means of Rutherford backscattering followed by spectrum analysis. The damage distribution and annealing behavior of implanted Er ions in SOI at the energy of 400 keV with dose of 5 × 10¹⁵ cm⁻² were obtained by Rutherford backscattering technique. It has been found that the damage around the SOI surface had been almost removed after annealed in nitrogen atmosphere at 900 °C, and a lot of Er atoms segregate to the surface of sample with the recrystallization of surface Si of SOI sample after annealing at 900 °C.     

Depth distribution and migration of helium in vanadium at elevated temperatures

The depth profiles and retention behavior of ⁴He implanted at 80 keV into vanadium have been investigated in cold rolled bulk and foil samples. The specimens were implanted at temperatures of 100, 400, and 800° C and at fluences up to 1 × 10¹⁸He/cm². Helium depth distributions were found to be Gaussian for the 100° C implants but exhibited a double peak appearance for some of the highest fluence 400° C and 800° C implants. In polished samples blistering and flaking occurred at both 100° C and 400° C implant temperatures for fluences greater than 5 × 10¹⁷He/cm², but little of the implanted helium appeared to have been released at a result of the exfoliation. Conversely, most of the implanted helium was released from 800 C implant areas though no significant blistering or surface perforation was observed. Blistering was observed to occur only on polished samples, through the release behavior was similar to that of the unpolished specimens on which no blistering was observed at any temperature or fluence. The surface condition of samples polished by different techniques was found to exert an influence on the temperature dependence of release and on the character of the blister topography.     

Behavior of an indigenously fabricated transferred arc plasma furnace for smelting studies

The utilization of industrial solid waste for metal recovery requires high-temperature tools due to the presence of silica and alumina, which is reducible at high temperature. In a plasma arc furnace, transferred arc plasma furnace(TAP) can meet all requirements, but the disadvantage of this technology is the high cost. For performing experiments in the laboratory, the TAP was fabricated indigenously in a laboratory based on the different inputs provided in the literature for the furnace design and fabrication. The observed parameters such as arc length, energy consumption, graphite electrode consumption, noise level as well as lining erosion were characterized for this fabricated furnace. The nitrogen plasma increased by around 200 K(200 ℃) melt temperature and noise levels decreased by ~10 d B compared to a normal arc.Hydrogen plasma offered 100 K(100 ℃) higher melt temperature with ~5 d B higher sound level than nitrogen plasma. Nitrogen plasma arc melting showed lower electrode and energy consumption than normal arc melting, whereas hydrogen plasma showed lower energy consumption and higher electrode consumption in comparison to nitrogen plasma. The higher plasma arc temperature resulted in a shorter meltdown time than normal arc with smoother arcing. Hydrogen plasma permitted more heats, reduced meltdown time, and lower energy consumption, but with increased graphite consumption and crucible wear. The present study showed that the fabricated arc plasma is better than the normal arc furnace with respect to temperature generation, energy consumption, and environmental friendliness. Therefore, it could be used effectively for smelting-reduction studies.     

Comparison of High-Energy He+ and D+ Irradiation Impact on Tungsten Surface in the IR-IECF Device

Polycrystalline tungsten specimens were irradiated in the Iranian Inertial Electrostatic Confinement Fusion device (IR-IECF) by high energy (~100 keV) and high fluency (~10¹⁹ ions/cm²) helium and deuterium plasma to investigate the implantation impact of high energetic ions on tungsten as a candidate for fusion first wall material. Comparison of the exposure by He and D₂ plasma and influence of high temperature (~1,100 °C) implantation of each ion has been examined. Scanning electron microscopy was used to investigate surface morphology changes for various ion fluencies. Results showed the onset of visible surface pores formation especially for helium implanted samples which increased with higher implant fluencies, eventually resulting in a rough and flaky surface structure, unlike deuterium implanted samples on which smoothening of the surface occurred. Microhardness measurements were used to evaluate mechanical properties of implanted tungsten. Each specimen sustained surface hardening after implantation which was observed to increase with greater ion dose. The phase formation and structural evolution were studied by X-ray diffractometry method.     

The effect of temperature on the structure of tantalum nitride (TaN) thin films deposited by DC plasma

In this work, we report the effect of growth temperature (room temperature, 150, 200 and 250°C) during the deposition of tantalum nitride thin films by a reactive planar DC magnetron sputtering system on the steel substrates, in a constant nitrogen partial pressure of 15% has been studied. The X-ray spectrum of deposited tantalum nitride films indicated an increasing in intensity of sharp peak of hexagonal TaN and was evidence of grain growth at higher temperatures. By increasing temperature the streaks’ directions, observed from AFM micrographs, were varied.     

Surface exfoliation and defect structures in Si induced by 160 keV He and 110 keV H ion implantation

Cz n-type Si(100) wafers were implanted at room temperature with 160 keV He ions at a fluence of 5 × 10¹⁶/cm² and 110 keV H ions at a fluence of 1 × 10¹⁶/cm², singly or in combination. Surface phenomena and defect microstructures have been studied by various techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM). Surface exfoliation and flaking phenomena were only observed on silicon by successive implantation of He and H ions after subsequent annealing at temperatures above 400 °C. The surface phenomena show strong dependence on the thermal budget. At annealing temperatures ranging from 500 to 700 °C, craters with size of about 10 μm were produced throughout the silicon surface. As increasing temperature to 800 °C, most of the implanted layer was sheared, leaving structures like islands on the surface. AFM observations have demonstrated that the implanted layer is mainly transfered at the depth around 960 nm, which is quite consistent with the range of the ions. XTEM observations have revealed that the additional low fluence H ion implantation could significantly influence thermal growth of He-cavities, which gives rise to a monolayer of cavities surrounded by a large amount of dislocations and strain. The surface exfoliation effects have been tentatively interpreted in combination of AFM and XTEM results.     

热处理工艺对冷旋U-6.5Nb合金电化学腐蚀行为的影响

采用冷旋方法制备了管状U-6.5Nb合金零件,分别在400、600和700℃下对合金零件进行1h退火处理,考察了不同状态的U-6.5Nb合金在含50μg/gCl-的氯化钾水溶液中的电化学腐蚀行为,采用扫描电镜表征了腐蚀前后的形貌特征。结果表明：所有状态的合金均未发生钝化,冷旋态和700℃退火态合金为单相组织,具有较高的腐蚀电位和较小的腐蚀电流,400℃退火和600℃退火态合金为双相组织,具有较低的腐蚀电位和较大的腐蚀电流。单相合金比双相合金具有更好的抗腐蚀能力,但更易发生点蚀。双相合金表面Nb成分不均是其抗腐蚀性不佳的主要原因。     

Oxidation kinetics of magnesium alloys treated by tantalum ions implantation

AZ31 magnesium alloys were implanted with tantalum ions with doses of 1 × 10¹⁶, 5 × 10¹⁶ and 1 × 10¹⁷ ions/cm², using a metal vapor vacuum arc (MEVVA) at an extraction voltage of 45 kV. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) analysis suggested that tantalum ions implantation promoted the formation of the pre-oxidation layer and a new Ta₂Al phase was formed in the implanted layer. Then, the oxidation kinetics of the implanted specimens was investigated by isothermal oxidation at 773 K in pure O₂ up to 90 min. The results showed that after implantation treatments the oxidation resistance of the specimens was significantly improved and the specimen with the highest dose had the best oxidation resistance. Finally, the mechanism of the anti-oxidation effects was also discussed.     

The Effect of High Temperature He+ Implantation on Polycrystalline Tungsten in IR-IECF

High temperature (1,100–1,200°C) implantation impact of helium ions in PC Tungsten as a candidate fusion first wall material was studied in the Iranian Inertial Electrostatic Confinement device (IR-IECF). High energetic (100–120?keV) helium ions were applied to produce fluences up to 5?×?10²⁰ He⁺/cm² on the surface of Tungsten. Scanning electron microscopy (SEM) was used to investigate surface morphology changes for various ion fluences. The results showed formation of ‘coral-like’ surface structure and exfoliation and intensive increment in pore formation at high fluence. Microhardness measurements were used to evaluate mechanical properties of implanted tungsten. These investigations revealed that hardness increased with greater He⁺ dose. The phase formation and structural evolution were studied by X-ray diffractometry method.     

Sub-surface retention of Pb atoms in silicon after low-energy ion implantation and electron beam annealing

Low-energy Pb ion implantation into (1 0 0) Si and subsequent high-vacuum electron beam annealing was used to study the potential of sub-surface retention of Pb atoms after applying a high temperature annealing process. 7 keV Pb⁺ ions were implanted into p-type (1 0 0) Si at room temperature with a fluence of 4 × 10¹⁵ ions cm⁻². The implantation results in a Pb depth distribution that has a calculated Pb peak concentration of 23.9 at.% at a depth of 8.0 nm. The Pb implanted Si substrates were annealed with a high-current 20 keV electron beam at 200-700 °C for 15 s. The Pb loss by out-diffusion was measured with RBS. Key results are: (i) minimal Pb loss in samples annealed up to 400 °C, (ii) emerging out-diffusion above 400 °C, (iii) retention of Pb atoms in the near-surface region in samples annealed up to 700 °C. Comparison of the RBS data with the calculated evaporation rate of Pb under similar conditions reveals two distinctive temperature ranges in which the measured Pb loss of the implanted samples disagrees with the calculated Pb loss: (1) Pb atoms diffused out of the samples at a higher rate in the temperature range up to 400 °C and (2) the Pb atoms diffused out of the samples at a much slower rate above 450 °C. Both phenomena are attributed to the ion implantation process.     

铍的高温氧化行为及特性研究

在不同温度下对金属铍（Be）进行热氧化,采用热重、AES和SEM对Be的热氧化过程、氧化后表面状态、微区成分和氧化层厚度进行表征和分析,探讨了不同温度下Be的氧化行为和氧化特性。结果表明：室温～400 ℃范围内,Be样品的氧化增重主要服从抛物线规律;400～900 ℃范围内,主要呈线性变化。在较低温度下,Be表面形成的钝化层具有良好的保护作用,比较耐蚀。高温对Be样品的氧化影响较大,认为600 ℃以下Be的氧化主要受Be原子向表面的热扩散控制;800 ℃以上,氧通过晶界和孔洞扩散进入材料体内、氧化膜受热膨胀以及应力作用开裂等,导致Be发生严重的氧化腐蚀。     

Fabrication and characterization of fine-grained 316L steel with 2.0 mass% TiC

Development of fine grain 316L with small amount of TiC for high radiation-tolerant performance was tried considering the fabrication process of thermo-mechanical treatments. The materials obtained are UFG316L+2.0 mass% TiC with the grain size of 90–270 nm, depending on the final annealing temperature from 700 ℃ to 900 ℃. The materials were examined by transmission electron microscopy observation, X-ray absorption near-edge structure spectroscopy, high voltage electron microscope electron irradiation and stress corrosion cracking by crevice bent beam method in high-temperature water with 8 ppm dissolved oxygen. The test results showed that the material is generally of excellent quality. Especially void swelling induced by the electron irradiation at 400 ℃ is less than 1/10 compared to the commercial SUS316L.     

Temperature and dose dependences of nitrogen implantation into aluminium

It has been established that nitrogen implantation into metals can alter their surface properties such as friction, wear, corrosion, etc. Recent studies have shown that nitrogen implantation into aluminium leads to the formation of aluminium nitride which has interesting tribological, electronic and optical properties. For a given implantation energy, the characteristics of the nitrogen profile, e.g. thickness, shape and concentration, depend strongly on the experimental conditions during the implantation. In order to study the influence of the implantation parameters, aluminium samples have been bombarded with ¹⁵N⁺₂ of 100 keV to different doses ((1–20) × 10¹⁷ N⁺/cm²), at several temperatures (25–300° C). Distributions of the implanted species were investigated by nuclear reaction analysis (NRA) and by Rutherford backscattering spectroscopy (RBS). The chemical bonds of aluminium in the matrix were studied by using low-energy electron-induced X-ray spectroscopy (LEEIXS). It is shown that aluminium nitride is formed and that the nitrogen distribution presents a surface peak when the implantation temperature is higher than 200° C.     

AL-6XN合金在超临界水中的应力腐蚀研究

采用慢拉伸试验研究了AL-6XN合金在550~650℃、25 MPa超临界水中的应力腐蚀行为,使用扫描电镜观察了材料断口形貌与标距面裂纹分布。结果显示:550℃试验条件下材料表现为穿晶开裂,标距面裂纹很多且分布较均匀,试样边角处出现扇形河流花样;650℃试验条件下材料表现为沿晶开裂,断口呈现典型的冰糖状,标距面裂纹数量大幅减少且集中于断口附近,相应的延伸率和断面收缩率也大幅降低。质子辐照对AL-6XN宏观力学性能影响不大,但导致试样断口的扇形花样(起裂源)数量增加,解理台阶宽度增大。以上结果表明,AL-6XN在超临界工况下具有严重的应力腐蚀开裂敏感性,升高温度和质子辐照会明显提高材料的应力腐蚀敏感性。     

钒的活化及钒氢化物性能研究

真空条件下,金属钒长时间高温除气、反复吸放氘气,最终活化并饱和吸氘到氘、钒原子比接近2.0。实验确定的活化条件为：真空度2～3Pa,活化温度400℃,活化时间4h,初始吸附温度80～100℃,初始吸附压力0.6～3.4MPa,2～3次反复吸放纯化氘气。实验测得钒氢化物性能参数为：室温平衡压,0.2MPa;饱和吸附容量,0.47L/g;500℃时保留量,6.1%;200℃时平衡压,60MPa。实验研制的钒氢化物高压气源已成功用于惯性约束聚变高压充氘氚实验。     

钽在硫酸-甲醇体系中的电抛光工艺研究

为制备出高温高压状态方程（EOS）研究中所需的高质量钽膜,采用硫酸 甲醇体系电解液对钽片进行电解抛光实验,测定了钽的阳极极化曲线,表征了钽样品抛光前后的表面形貌,分别研究了电解液配比、抛光电压、搅拌速率和电解液温度等因素对抛光效果的影响。抛光后钽表面均方根粗糙度和形貌测试结果表明,硫酸 甲醇体系适用于钽的电解抛光,并初步确定了钽的电解抛光工艺参数,即硫酸与甲醇体积比为1∶7,电解电压为15～20 V,温度为-10～0℃,搅拌速率大于8m/s。     

中子吸收材料Fe-TbFeO_3-DyFeO_3的制备及性能研究

采用粉末冶金工艺制备了Fe-TbFeO_3-DyFeO_3块体材料。利用X射线衍射仪、扫描电子显微镜和透射电子显微镜对球磨粉末和烧结块体进行了微观组织分析,测试了块体材料的热物理性能、耐腐蚀性能和离子辐照性能。实验结果表明,通过球磨可获得混合均匀的Fe-Tb_4O_7-Dy_2O_3纳米尺寸颗粒的混合粉末。高温下Tb_4O_7转变成Tb_2O_3,烧结块体中的Tb_2O_3和Dy_2O_3的含量随烧结温度升高而降低,在1 200℃烧结24h可获得Fe-TbFeO_3-DyFeO_3块体材料。Fe-TbFeO_3-DyFeO_3块体材料具有高的热导率和低的热膨胀系数,腐蚀性能较差。在400~600℃辐照至25dpa,随辐照温度升高辐照肿胀率逐渐降低,400℃辐照肿胀率最大为0.5%。