Nb和Al对γ-TiAl基合金高温强度的影响

研究了Nb对γ TiAl基合金性能的影响 ,结果表明 ,高Nb合金化能大大提高γ TiAl基合金的高温强度 ,合金含Nb量越高 ,强度就越高。TEM观察表明 ,Nb对γ TiAl性能的影响类似于氧元素 ,增强d—d键的方向性 ,增加普通位错的P N力 ,提高普通位错开动的临界分切应力和滑移阻力。Al对γ TiAl合金性能的影响是通过影响合金中的α2 相含量来影响其性能的。随合金中Al含量升高 ,α2 相含量减少 ,位错运动非热激活阻力降低 ,合金的强度下降。     

双相TiAl合金α2/γ界面电子结构计算与增韧机制分析

基于余氏固体与分子经验电子理论(EET)和程氏改进的TFD理论提出了计算双相TiAl合金层片状结构α2/γ界面电子结构的计算模型与方法,计算了含常用合金元素的单相TiAl合金与双相TiAl合金中的异相界面的电子结构,利用界面电子结构给出的信息-界面结合因子ρ, △ρ,σ,以合金元素Mn为例初步分析讨论了双相TiAl合金层片状结构增加韧性的微观机制.     

双相TiAl合金α2／γ面电子结构计算与增韧机制分析

基于余氏固体与分子经验电子理论(EET)和程氏改进的TFD理论提出了计算双相TiAl合金层片状结构α2／γ界面电子结构的计算模型与方法，计算了含常用合金元素的单相TiAl合金与双相TiAl合金中的异相界面的电子结构，利用界面电子结构给出的信息-界面结合因子ρ，Δρ,σ，以合金元素Mn为例初步分析讨论了双相TiAl合金层片状结构增加韧性的微观机制。     

钴基合金Co-Al-W-Ta-Nb的显微组织与高低温力学性能

以新型Co基合金Co-9Al-9W-2Ta为基础,分别用4at%、6at%和9at%的Nb元素替代等量的W(分别称4Nb、6Nb、9Nb合金,无Nb添加的称为0Nb合金),研究Nb含量对合金显微组织和高低温力学性能的影响。结果表明:铸态组织由Co基固溶体γ相和γ+Co3Nb共晶组成(Nb可部分被W和/或Ta取代),随Nb含量提高,共晶组织体积分数增大。1200℃/8h固溶+800℃/100h时效处理后,γ中析出尺寸为数百纳米并与之共格的γ’-Co3(Al,W)相或Co3Nb相,显微组织由γ/γ’组织(0Nb)逐步向γ/γ’/Co3Nb组织(4Nb和6Nb合金)和γ/Co3Nb组织转变(9Nb合金)。合金在600℃开始出现反常屈服,反常屈服强度峰值对应温度大约在700℃。     

Ti-47Al-2Cr-2Nb-0.2W-0.15B合金板材的制备及其拉伸性能

采用感应熔炼气体雾化法制备Ti-47Al-2Cr-2Nb-0.2W-0.15B预合金粉末,对预合金粉末进行表征,通过热等静压工艺制备TiAl基合金坯料.应用包套叠轧的方法轧制出TiAl基合金板材,对轧制的TiAl基合金板材进行不同相区的热处理,分别得到双态组织和全片层组织,对热处理后的TiAl基合金进行拉伸性能测试.结果表明:TiAl基合金的预合金粉末主要由α2相和少量γ相组成,热等静压致密化处理后的板坯组织细小均匀.拉伸实验表明,双态和全片层组织的TiAl基合金板材在高于700 ℃时,其塑性大幅提高;双态组织TiAl基合金板材的断裂形式主要以韧性断裂为主,而全片层TiAl基合金板材的断裂形式仍为脆性断裂.     

Nb、Mo对TiAl基合金高温氧化行为的协同效应研究

采用冷坩埚悬浮熔炼技术制备Nb、Mo合金化的TiAl基合金,研究合金在大气环境中的高温长时氧化行为。采用X射线衍射、扫描电镜及能谱分析研究氧化层的相结构、显微组织及与基体合金的界面特征,结合氧化动力学测试研究Nb、Mo对TiAl基合金高温抗氧化行为的协同效应。结果发现,Nb、Mo协同作用较单一元素合金化的TiAl合金具有更为优良的高温抗氧化性,连续致密且与基体良好结合的氧化膜可明显降低合金的氧化速率、减小氧化增重。Nb、Mo掺杂的TiAl基合金氧化层可阻止氧原子向内扩散,Nb、Mo的协同效应有助于改善TiAl基合金的高温抗氧化性。     

热暴露对Ti-44Al-4Nb-4Hf-1B合金显微结构和力学性能的影响

对合金Ti-44Al-4Nb-4Hf-1B在700℃大气气氛中开展了长达10 000 h的热暴露处理,系统地探索和分析含Nb-Hf的TiAl合金的高温热稳定性,采用透射电镜和扫描电镜观察合金的显微组织变化并测试相应的力学性能.研究发现:长期大气高温热暴露导致合金中α2+γ层片晶团内的a2层片发生了一定程度的α2→γ相变:部分α2层片转变成为细小的γ层片,到10 000 h时,α2层片的原始厚度减少了约一半.长期大气高温热暴露也导致合金中α2+γ层片条束上发生了α2+γ→B2(ω)相变:条束上部分α2+γ消失,代之以微米及亚微米尺度的B2(ω)块状相.在10 000 h时,其面积分数达到8.4％,随着高温热暴露的逐渐进行,合金的室温塑性伸长率逐渐降低.在10 000h时,合金的塑性约为热暴露前的2/3,表明在复合含Nb+Hf的TiAl合金中,热暴露所导致的“释氧脆化”和“B2+ω生成脆化”的影响有限.复合含Nb+Hf的TiAl合金具有优于单纯含Nb的TiAl合金的高温热稳定性.长期高温热暴露对合金的断裂强度和条件屈服强度没有明显的有害影响.在10 000 h时,其条件屈服强度总体上仍保持在600MPa级别,而合金的室温疲劳极限还有所提高.     

TiAl-W-Si合金中的偏析与析出相的分析电子显微术研究

用高空间分辨分析电子显微术研究了TiAl-W-Si合金中B2相的析出行为和元素W的分布.结果表明,α2/γ相界面台阶由于W的富集而成为B2析出相的择尤形核位置.B2相中,高达三分之一的Al原子被W原子置换,而在γ相中只固溶了很有限的W.另外,W也偏析在α2/γ和B2/γ相界面上.这些结果合理地解释了W对提高TiAl合金蠕变性能的显著作用.     

Y, Nb对快速凝固TiAl合金组织和性能的影响

研究了元素Y和Nb对用熔体快淬法制备的TiAl基快速凝固合金组织及性能的影响。发现添加Y的快速凝固TiAl合金主要为等轴晶,主要组成相为α2和少量的γ相。随着Y含量的增加,γ相的含量增加,快速凝固TiAl合金的组织逐渐细化。不同Nb含量的快速凝固TiAl合金的组织为块状结构和层片状结构,主要由γ和α2两相组成,层片间距显著细化,为15～17nm。快速凝固TiAl合金的硬度比其铸态合金显著提高。     

TiAl/Ti_2AlNb放电等离子扩散接头的组织性能研究

采用放电等离子扩散连接方法,对TiAl/Ti_2Al Nb合金进行了扩散连接,分析了焊接接头的显微组织和物相组成,并检测了焊接接头的拉伸强度和显微硬度。结果表明,放电等离子扩散焊可实现TiAl合金和Ti_2AlNb合金的无缺陷连接。焊接过程中Ti_2AlNb母材侧发生了O/α_2向B_2相转变,Ti_2AlNb热影响区由部分相变区、过渡区和完全相变区组成,TiAl母材侧显微形貌无明显变化,但有少量的α_2转变为α相;界面处组织由等轴的TiAl晶粒、(α+α_2)相和少Nb的B_2相构成;界面处显微硬度值最高;接头室温拉伸强度可达300 MPa。     

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.