纯钨高压扭转组织与性能的微观尺度分析

采用高压扭转技术在550 ℃、1.5 GPa压力下成功制得具有细晶组织的难熔金属钨,借助EBSD技术研究了高压扭转变形组织晶粒尺寸、晶界角度以及晶粒取向的演化规律,结合纳米压痕实验结果,分析了应变对工业烧结纯钨微观力学性能的影响机理。实验结果表明,高压扭转后材料内部微孔隙有效闭合,组织细化显著,大角度晶界含量快速升高。在应变较低时出现较为明显的沿<101>方向的择优取向;随着应变的增加,择优取向消失,组织趋于均匀。应变较高(扭转5圈)时在三叉晶界处出现了细小的动态再结晶晶粒。高压扭转变形引起的孔隙闭合、晶粒细化、晶格畸变、位错密度增加和大角度晶界形成,导致屈服强度和纳米硬度随变形量的增大而不断提升;而在致密度、残余内应力和高密度位错的共同作用下,变形试样的弹性模量显著高于工业烧结纯钨,但随着应变量的增大略有降低。     

纳米压痕法确定TSV-Cu的应力-应变关系

为得到硅通孔电镀填充铜(TSV-Cu)的力学性能,对TSV-Cu进行了Berkovich纳米压痕实验.基于Oliver-Pharr算法和连续刚度法确定TSV-Cu的弹性模量和硬度分别为155.47 GPa和2.47 GPa;采用有限元数值模拟对纳米压痕加载过程进行反演分析,通过对比最大模拟载荷与最大实验载荷,确定TSV-Cu的特征应力和特征应变;由量纲函数确定的应变强化指数为0.4892;将上述实验结果代入幂强化模型中,确定TSV-Cu的屈服强度为47.91 MPa.最终确定了TSV-Cu的幂函数型弹塑性应力-应变关系.     

HPT不同压力下纯钼的组织和性能及热稳定性

通过高压扭转实验,在350℃条件下将纯钼粉末制备成相对密度达98%以上的金属钼坯,利用多种检测手段分析了高压扭转过程中钼粉颗粒孔隙演变及致密强化规律。通过改变预压钼坯压力参数,探讨了压力对压扭钼坯微观结构和力学性能及其热稳定性的影响。结果表明:压力由2.0 GPa增大到3.0 GPa,压扭钼坯致密度提升显著,其内部亚晶细化,微观应变增加,试样整体显微硬度值随压力增大而升高,边缘处略有降低。随压力增大,差热分析(DSC)后组织未发生显著长大,热稳定性较好。     

HPT不同压力下纯钼组织性能及热稳定性研究

通过高压扭转实验,在350℃条件下将难熔金属纯钼粉末制备成相对密度达0.98以上的金属钼坯,利用多种检测手段分析了高压扭转过程中钼粉颗粒孔隙演变及致密强化规律。通过改变预压钼坯压力参数,探讨了压力对压扭钼坯微观结构和力学性能及其热稳定性的影响。结果表明：压力由2.0GPa增大到3.0GPa,压扭钼坯致密度提升显著,其内部亚晶尺寸细化,微观应变增加,试样整体显微硬度值随压力增大而升高,边缘处略有降低。随压力增大,DSC后组织未发生显著长大,热稳定性较好。     

钨粉经高压扭转后韧性及热稳定性观察（英文）

采用高压扭转法,在440℃对纯钨进行大塑性变形(HPT)。硬度测试表明试样表面纯钨经高压扭转后硬度HV高达11 500 MPa。差热分析(DSC)结果表明等效应变较小的试样再结晶温度较高(高于1450℃),等效应变较大的试样再结晶温度较低(约800℃)。XRD分析结果表明试样晶格应变达0.35%,晶格常数达0.3177 nm,位错密度达2.4×10~(15) m~(-2)。高压扭转可以使纯钨在低温下实现固结并具有高强度,一定的韧性和热稳定性。     

高压扭转制备钛合金的工艺参数分析

为了进一步提高钛合金的综合力学性能，采用无约束高压扭转工艺对钛合金坯料进行了大塑性变形。采用有限元模拟方法对在轴向压力为3 GPa、剪切摩擦因数为1.0、扭转速度为0.628 rad·s^-1、扭转时长为10 s的条件下坯料的流动、表层等效应变、坯料的厚度和直径进行了分析。得出有限元模拟高压扭转的一般规律，即扭转后的钛合金的等效应变分布曲线呈“M”状分布。在上述条件不变的情况下，依次改变单一变量，分析参数对坯料变形的影响。结果表明，高压扭转后钛合金的等效应变分布曲线依然呈“M”状，且随轴向压力、剪切摩擦因数和扭转圈数的增大，坯料厚度减小，坯料直径增大。为了验证模拟的准确性，在仿真的基础上进行了实验研究，探究了变形后坯料厚度、直径以及硬度的变化，进一步说明了模拟的准确性。同时，变形后的坯料在力学性能方面有明显的改善，扭转参数和摩擦因数的不同会影响工件的变形程度。采用较大的剪切摩擦因数，增加轴向压力，可以获得变形大的工件，其力学性能也相对突出。     

高压扭转对难熔金属粉末组织致密及强化的影响

采用高压扭转法在350℃下将纯钼粉末直接制备成致密体材料。用金相显微镜、显微维氏硬度计、扫描电镜和X射线衍射仪分析高压扭转过程中粉末颗粒孔隙闭合及性能强化规律。结果表明:高压扭转后钼颗粒粉末在剪切力作用下通过移动和变形相互啮合联结,颗粒间大块链状孔隙逐渐缩小、闭合,此时颗粒间界面结合较好;高压扭转前后材料内部亚晶尺寸由59.8 nm细化到46.9 nm,微观应变由1.04×10~(-4)增大到1.12×10~(-3);晶粒细化和微观应变增大引起的晶格缺陷会促进晶粒内部位错增殖、缠结来强化基体。     

Al—Li合金高温扭转变形行为

在Ｇｌｅｅｂｌｅ２０００热模拟机上对一种２０１９Ａｌ－Ｌｉ合金进行高温扭转试验,研究了合金扭转时的等效应力－应变关系和扭转变形组织特征,研究结果表明：合金表现出与压缩变形类似的稳态流变特征,扭转等效应力随变形温度的升高和应变速率的降低而减小;其变形过程属于受位错速率机制控制的热激活过程,等效应力、等效应变速率和温度之间基本上满足以曲正弦函数关系,扭转等效应力随变形温度的升高和应变速率的降低而减小。     

纯钼粉末多孔烧结材料ECAP的数值模拟及实验

采用DEFORM-3D软件对纯钼粉末多孔烧结材料等径角挤压过程进行单道次三维有限元模拟和实验研究,获得变形过程中试样的应力、应变、致密行为等相关场量变化规律.模拟结果表明:等径角挤压工艺对粉末材料具有强烈的致密效果,整个变形过程可分为3个阶段,即初始变形、过渡变形及稳定变形;试样纵横截面上,等效应变均存在不均匀分布现象,靠近模具内角和上表面处试样所获应变较大,相对密度也较高.试样不同部位所处应力状态及应变速率分布状态的不一致是导致其应变分布不均匀的根本原因.单道次挤压实验结果与模拟结果具有较好的一致性,证明了所建立有限元模型的可靠性.     

ZK60镁合金高压扭转模拟及实验研究

为了研究高压扭转工艺对ZK60镁合金组织及性能的影响,采用有限元法对ZK60镁合金试样高压扭转成形过程进行数值模拟,分析成形过程中等效应力、应变分布及变化趋势。通过压扭设备和专用模具对镁合金试样进行高压扭转实验,采用金相显微镜观察试样的显微组织,利用维氏硬度计测量试样的显微硬度。结果表明:高压扭转能有效细化晶粒,改善材料组织结构;在一定的压力下,随着压扭圈数增加,晶粒得到细化,整体显微硬度有较大的提高;高压扭转后试样的显微硬度沿试样径向呈V型分布,与有限元模拟中试样径向的等效应变分布趋势一致。试样不同区域的等效应力、应变和显微硬度差异较大,边缘处的等效应力、应变最大,显微维氏硬度值最高。     

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.