65Mn钢强脉冲电子束轰击表面结构分析

研究结果表明,高功率密度强脉冲电子束作用于金属表面可产生骤熔急冷和冲击压缩过程,在金属表面注入区形成微米量级硬化层,使金属表面的物化性能得以改善。这项技术拓宽了脉冲电子束在材料科学中的应用。     

强流脉冲电子束作用下纯钛的微观组织结构变化及其性能研究

目的提高纯钛表面的耐腐蚀性能。方法本实验主要分两步进行,首先进行金相样品的制备,然后利用强流脉冲电子束对材料表面进行改性处理,最后利用扫描电镜(SEM)、X射线衍射仪(XRD)、硬度检测,电化学检测等检测手段进行探讨研究。结果扫描电镜分析结果表明,强流脉冲电子束处理后,样品表面出现了熔坑,并且随着脉冲次数的增加,熔坑数量逐渐减少,这主要归因于强流脉冲电子束的净化除杂作用。X射线衍射分析发现,强流脉冲电子束处理后,衍射峰出现了宽化和向高角度偏移现象,主要归因于脉冲处理后合金表面的晶粒细化和表面应力、晶格常数的降低。另外,电化学测试表明,强流脉冲电子束处理后金属表面的耐腐蚀性明显增加,自腐蚀电流密度从强流脉冲电子束处理前的27.3μA/cm~2变化到25次脉冲处理后的6.3μA/cm~2,主要归因于强流脉冲电子束的净化除杂作用以及熔坑等结构缺陷的消失。显微硬度分析发现,经过强流脉冲电子束处理后由于样品表面的残余应力和孪晶等结构缺陷的存在,样品表面硬度明显降低。结论强流脉冲电子束处理后,纯钛的耐腐蚀性能增加,晶粒细化,硬度有所降低。     

纳秒高能密度粒子束与瞬态作用过程研究

多极板赝火花 (Pseudospark)放电室 ,在外加直流电压下 ,能产生自收缩纳秒强脉冲电子束和多种离子束。电子束瞬间功率密度可达 10 10 W /cm2 。与高功率脉冲激光相似 ,该高能束流与物质相互作用将产生瞬态高温等离子体 ,并伴随高温、高压和烧蚀过程。本文将介绍用脉冲粒子束进行金属表面改性的试验方法 ,以及材料表面微区快速熔凝等一系列非平衡的物理、化学变化 ,阐述材料表面轰击前后显微结构、性能等分析测试结果 ,讨论了纳秒脉冲粒子束与固体介质间的瞬态作用过程。试验结果表明 ,纳秒脉冲电子束和离子束以其特有的作用过程 ,在材料表面改性、表面涂敷以及低维材料制备等领域中 ,有着诱人的应用前景     

强电流脉冲电子束表面合金化热应力耦合场模拟分析

电子束表面合金化处理是提高材料表面耐磨性和硬度的重要手段。以3Cr2W8V钢作为基体,以纯铝作为表面合金化材料,建立了脉冲电子束热力学模型,利用ANSYS软件分析了表面合金化热应力耦合场。结果表明,电子束合金化处理后,钢基体表层4μm范围内残余应力达到了材料的屈服极限,金属表面有熔坑;随着距表面深度的增加,残余应力骤减。     

强电流脉冲电子束表面合金化热应力耦合场模拟分析

电子束表面合金化处理是提高材料表面耐磨性和硬度的重要手段。以3Cr2W8V钢作为基体,以纯铝作为表面合金化材料,建立了脉冲电子束热力学模型,利用ANSYS软件分析了表面合金化热应力耦合场。结果表明,电子束合金化处理后,钢基体表层4μm范围内残余应力达到了材料的屈服极限,金属表面有熔坑;随着距表面深度的增加,残余应力骤减。     

脉冲电子束抛光改性处理对TC21钛合金表面形貌的影响

采用脉冲电子束对TC21钛合金表面进行照射处理,利用光学显微镜、原子力显微镜分析了表面形貌,在轮廓仪上测定了脉冲电子束处理前后试样的表面粗糙度Ra和Ry,利用扫描电镜对脉冲电子束改性处理与未处理试样的横截面进行观察和分析,研究脉冲电子束改性机理.试验结果表明,脉冲电子束可以显著改善TC21钛合金的表面粗糙度,其抛光改性的机理是厚约10 μm表层在脉冲电子束的照射下发生高温瞬时熔凝,使表面变得平整和光滑.     

电子束扫描对金属表面温度场的影响

电子束用于金属表面抛光,能有效去除金属表面的微缺陷,提高材料性能,从而延长工件的使用寿命。采用低功耗的赝火花放电装置可产生高频高密度的电子束,用于金属表面处理。然而,入射电子束能量的非均匀分布和扫描过程中工艺参数的不合理选择等会导致金属表面层上的温度场不均匀,进一步可能导致工件中产生残余应力,影响抛光后的表面质量。利用APDL对电子束抛光过程中的工件表面温度场进行了仿真分析。在考虑束源能量不均匀的情况下,分别研究了扫描过程中的束源功率、束斑重叠率和扫描次数三个主要工艺参数对表面温度场的影响,这将有利于获得更优的工艺参数组合,从而获得更好的表面质量和更高的加工效率。     

强流脉冲电子束改性过程温度场数值模拟

强流脉冲电子束表面改性过程具有非稳态、有内热源的温度场特点,利用ANSYS软件对其温度场进行了数值模拟。以纯镁板材为实验材料,采用强流脉冲电子束装置对试样表面进行了脉冲次数为10次的辐照处理。建立了强流脉冲电子束表面改性过程内热源的一维物理模型,并在实验和理论基础上对电子束改性过程中的温度场演化进行了数值模拟。模拟结果显示,所建立的物理模型与实验结果较为吻合。     

薄板TC4钛合金脉冲电子束焊接技术研究

脉冲电子束焊接是指将电子束流调制成脉冲方波的形式进行焊接的一种先进技术。脉冲束流能提高被焊金属蒸发率,从而提高焊接效率、增加焊缝深宽比。本文采用常规直流电子束和不同频率脉冲电子束对1.2 mm薄板TC4钛合金进行了焊接工艺试验,并对接头进行了微观组织与力学性能检测。结果表明：脉冲电子束焊接能够形成无熔合缺陷的焊缝,随着频率的增加,焊缝咬边和背面余高减小,表面成形得到改善;由于焊接热循环变化,脉冲束流可加快熔池冷却速度,细化组织晶粒;直流和脉冲电子束焊接接头拉伸时均断裂在母材区,拉伸强度不低于母材;高频脉冲电子束可提升焊接接头塑性和焊缝区、热影响区的显微硬度,频率为10 kHz时,焊接接头的断后伸长率可达14.9%,约为母材的80%,焊缝区和热影响区的显微硬度分别为375 HV和368 HV。     

强流脉冲电子束改性过程温度场数值模拟

强流脉冲电子束表面改性过程具有非稳态、有内热源的温度场特点,利用ANSYS软件对其温度场进行了数值模拟。以纯镁板材为实验材料,采用强流脉冲电子束装置对试样表面进行了脉冲次数为10次的辐照处理。建立了强流脉冲电子束表面改性过程内热源的一维物理模型,并在实验和理论基础上对电子束改性过程中的温度场演化进行了数值模拟。模拟结果显示,所建立的物理模型与实验结果较为吻合。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.