粗晶Mg-6.8Gd-4.5Y-1.1Nd-0.5Zr合金高温变形行为

采用Gleeble-1500热模拟机研究粗晶Mg-6.8Gd-4.5Y-1.1Nd-0.5Zr镁合金在温度为623～803 K、应变速率为0.005～5 s-1条件下的高温变形行为。结果表明:流动应力随变形温度的降低或应变速率的升高而增加,在高温变形初始阶段,流动应力随应变的增加迅速增加,当应变超过一定值后,流变应力开始下降并逐渐趋于稳定,出现稳态流动特征;基于Arrhenius方程建立Mg-6.8Gd-4.5Y-1.1Nd-0.5Zr合金高温流变应力本构模型;在723 K、应变速率0.05 s-1条件下,显微组织出现大晶粒被细小晶粒包围的"项链"组织特征,局部晶粒交结处出现微裂纹与孔洞;根据实验结果,合金的热加工宜在773 K左右进行。     

Mg-11.8Gd-2.8Y-0.44Zr耐热镁合金热压缩变形行为研究

采用Gleeble-1500热/力模拟机,对Mg-11.8Gd-2.8Y-0.44Zr耐热镁合金在温度为573～723 K,应变速率为0.001、0.010、0.100 s-1,应变量为60%的塑性变形行为以及热压缩后镁合金组织的变化进行了研究.分析了流变应力与应变速率和温度的关系.结果表明,合金的稳态流变应力随应变速率的增大而增大,在恒应变速率条件下,合金的真应力水平随温度的升高而降低,根据试验分析,合金的热加工宜在623 K时进行.     

Mg-5Y-0.5Ce-0.5Zr合金的热压缩行为

在变形温度为300～450 oC、应变速率为0.01～1 s-1的条件下进行热压缩试验，对Mg-5Y-0.5Ce-0.5Zr镁合金的热变形行为进行了研究。结果表明，在热压缩变形过程中，该合金的流变应力随着变形温度和应变速率的变化而变化。在同一应变速率下，流变应力随着变形温度的增高而降低；在同一变形温度下，流变应力随着应变速率的减小而减小。该合金热压缩流变应力的本构方程可采用双曲正弦形式构建，热变形激活能Q为253 kJ/mol。     

Mg-13Gd-4Y-2Zn-0.6Zr合金高温本构方程及加工图

采用Gleeble-3500热模拟试验机,研究Mg-13Gd-4Y-2Zn-0.6Zr合金在300℃~500℃、应变速率0.001s-1~1s-1时的高温流变行为,获得了合金的真应力-应变曲线。实验结果表明,随着温度上升、应变速率下降,合金的流变应力、峰值应力和峰值应变均减小。利用真应力-应变数据,进行数值拟合、回归计算,求得合金的热变形激活能Q为273.4kJ·mol-1,并建立该合金的流变应力本构模型,该模型结果与实验数据的最大误差小于5%。同时,根据动态材料模型,计算并得到了该合金在不同真应变下的热加工图,分析了其变化规律。并以真应变为0.7的热加工图为依据,结合材料的微观组织,确定了该合金的最佳变形工艺为480℃/0.01s-1。利用金相图解释了各失稳区的组织演变特点。     

Mg-8Li-2Al-1Zn合金的热变形行为

采用Gleeble-1500D热模拟机对Mg-8Li-2Al-1Zn合金进行热压缩实验,研究了变形温度为523~723 K、应变速率为0.01~10 s-1条件下的合金热变形行为,并建立了合金的流变应力本构方程及热加工图。结果表明:Mg-8Li-2Al-1Zn合金的流变曲线均属于动态再结晶型,流变应力随着温度升高(应变速率降低)而减小。显微组织的变化验证了动态回复和动态再结晶的发生。Mg-8Li-2Al-1Zn合金流变应力本构关系可以用双曲正弦函数和Z参数准确的描述,平均应力指数为4.62,平均热激活能为139.35 J/mol。根据建立的加工图,预测合金热变形的最佳工艺参数为:523~573 K,0.1~1 s-1。     

Mg-13Gd-4Y-2Zn-0.5Zr合金形变软化行为及本构方程建立

使用型号为Gleeble-3500的热压缩实验机进行热压缩实验,在实验中调控温度和应变速率,绘制流变应力曲线图并进行分析。对Mg-13Gd-4Y-2Zn-0.5Zr合金在温度为360~480℃、应变速率为0.001~1 s^-1、并且热压缩试样的最大变形程度为60%条件下的形变软化现象进行了研究。经研究发现,Mg-13Gd-4Y-2Zn-0.5Zr合金的形变软化行为主要受其在不同变形条件下的动态再结晶行为的影响。设定材料常数α、n、A和Q与应变构建影响关系,将应变考虑在内后,建立了Mg-13Gd-4Y-2Zn-0.5Zr合金本构方程,其平均变形激活能为232.54 kJ·mol^-1。进行了误差检验,得到的峰值应力的实验值与计算值的平均相对误差的绝对值仅为5.5%,说明了建立的本构模型精度较高。     

Mg-3.5Zn-0.6Y-0.5Zr合金高温压缩变形行为

采用Gleeble-1500D热模拟实验机,研究了Mg-3.5Zn-0.6Y-0.5Zr合金在变形温度为300~450℃、变形速率为0.002~1s-1及变形量为50%的条件下的高温压缩变形行为,分析了流变应力与应变速率、变形温度的关系,计算了高温变形时变形激活能和应力指数,建立了该合金的本构方程。结果表明:Mg-3.5Zn-0.6Y-0.5Zr合金在热变形过程中真应力随着温度的升高而降低,真应力随着应变速率的升高而升高。该合金的流动应力可以用双曲正弦函数来描述。     

生物医用镁锌钇钕合金热变形行为的研究

采用GLEEBLE 1500热模拟机对挤压Mg-2.3Zn-0.5Nd-0.4Y生物医用镁合金在温度为200~400℃、应变速率为0.001~0.100 s-1、最大变形程度为60%的条件下,进行压缩模拟实验研究,分析了实验合金在热变形时的流变行为。实验表明此合金是正的应变速率敏感材料。合金的峰值流变应力随应变速率的增大而增加,随温度的升高而降低;应力-应变曲线以动态再结晶软化机制为特征,热变形应力指数n为4.0035,变形激活能Q为108.04 kJ/mol,流变应力行为满足双曲正弦关系,本构方程为:??=A[sinh(ασ)]nexp[–Q/(RT)]=1.1498×107[sinh(0.0133σ)]4.0035exp[–108.04/(RT)],该本构关系模型的计算结果与实验值间相对误差小于10%,为确定该医用镁合金的后续热加工提供了理论依据。     

Mg-6Zn-1Mn镁合金的热压缩变形行为及加工图

采用Gleeble-1500热/力模拟试验机进行压缩试验,研究了Mg-6Zn-1Mn合金在变形温度250～450℃、应变速率0.001～10 s-1范围内的流变应力行为,采用Zener-Hollomon参数法构建合金高温塑性变形的本构关系;并以热压缩试验为基础,建立并初步分析了Mg-6Zn-1Mn合金的DMM加工图。结果表明:Mg-6Zn-1Mn合金在热压缩过程中发生了明显的动态回复与动态再结晶,流变应力随应变速率的增加而增加,随温度的升高而降低;流变应力的预测值与试验值较吻合;建立的加工图表明合金高温变形时存在2个失稳区域,而在温度325～425℃、应变速率0.01～0.365 s-1范围内出现1个非失稳区、功率耗散峰值区,该区域最适合Mg-6Zn-1Mn合金进行热加工。     

超细晶不锈钢/TiC复合材料的电化学腐蚀行为

采用Gleeble-1500热/力模拟试验机进行压缩试验,研究了Mg-6Zn-1Mn合金在变形温度250～450℃、应变速率0.001～10 s-1范围内的流变应力行为,采用Zener-Hollomon参数法构建合金高温塑性变形的本构关系;并以热压缩试验为基础,建立并初步分析了Mg-6Zn-1Mn合金的DMM加工图.结果表明:Mg-6Zn-1Mn合金在热压缩过程中发生了明显的动态回复与动态再结晶,流变应力随应变速率的增加而增加,随温度的升高而降低;流变应力的预测值与试验值较吻合;建立的加工图表明合金高温变形时存在2个失稳区域,而在温度325～425℃、应变速率0.01～0.365 s-1范围内出现1个非失稳区、功率耗散峰值区,该区域最适合Mg-6Zn-1Mn合金进行热加工.     

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.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.