挤压铸造准晶增强AZ91D镁基复合材料组织与性能（英文）

为了改善AZ91D镁合金的性能,采用挤压铸造法制备了Mg-Zn-Y准晶中间合金增强AZ91D镁基复合材料,研究了准晶中间合金含量对复合材料组织和性能的影响。结果表明挤压铸造工艺可以有效细化晶粒,复合材料的显微组织主要由α-Mg基体、晶界上分布的β-Mg_(17)Al_(12)相以及Mg_3Zn_6Y准晶颗粒组成,准晶颗粒和α-Mg基体之间形成稳定结合。当准晶中间合金含量为5%时,抗拉强度和断后伸长率达到最大值,分别为194.3 MPa和9.2%。复合材料的强化机制为细晶强化和准晶颗粒强化。     

压力对挤压铸造Mg-Zn-Y准晶增强AZ91D镁基复合材料显微组织和力学性能的影响(英文)

采用挤压铸造工艺制备Mg-Zn-Y准晶增强AZ91D镁基复合材料,研究挤压压力对此复合材料显微组织和力学性能的影响。研究结果表明:挤压铸造工艺是细化晶粒的有效方法,复合材料由α-Mg基体、β-Mg17Al12相以及二十面体Mg3Zn6Y准晶相(I相)组成,且随着挤压压力的增大,β-Mg17Al12相以及Mg3Zn6Y准晶颗粒含量增加,基体晶粒进一步细化,α-Mg树枝晶向等轴晶转变;当挤压压力为100 MPa时,极限抗拉强度和断后伸长率达到最大值,分别为194.3 MPa和9.2%,拉伸断口出现大量韧窝;准晶增强AZ91D镁基复合材料的强化机制主要为细晶强化和准晶颗粒强化。     

镁基准晶对AZ91合金组织与性能的影响

通过采用扫描电子显微镜、能量散射光谱和透射电镜等分析手段,研究了两种不同成分和形态的准晶中间合金对AZ91合金显微组织与力学性能的影响。结果表明,在AZ91合金中加入镁基准晶中间合金后,在其铸态合金的显微组织中除α-Mg基体相、β-Mg17Al12相外还出现了弥散分布在α-Mg内部和晶界附近的高热稳定的准晶相;由于加入的准晶中间合金中准晶相的形貌不同,遗传效应不同,所以其细化效果也存在差异。经准晶强化的AZ91合金常高温拉伸强度明显提高,但用MZYM中间合金对力学性能的提高要远远大于用MZY合金。这为镁基合金的强化提供一条新途经。     

挤压铸造AZ91D镁合金的显微组织与力学性能

研究了挤压铸造AZ91D镁合金在不同热处理状态下的显微组织、力学性能以及厚度对镁合金试样力学性能的影响。结果表明,挤压铸造AZ91D镁合金铸态显微组织主要由基体α-Mg和在晶内及晶界上分布的β-Mg17Al12相组成,经固溶处理后得到单相α-Mg固溶体组织,而且在α-Mg晶粒内部也出现了少量颗粒状析出物,经固溶时效处理后β-Mg17Al12相再一次在α-Mg晶内和晶界析出,且晶粒变得更加细小;挤压铸造AZ91D镁合金的硬度、屈服强度、抗拉强度随着试样厚度的增加而减小,而伸长率随着试样厚度的增加而增加。     

SiC及Cu-SiC颗粒增强镁基复合材料的制备及性能

利用化学镀法制备了Cu包覆SiCp,研究了SiCp及Cu-SiCp增强镁基复合材料(SiCp/AZ91D和Cu-SiCp/AZ91D)的性能。采用扫描电镜(SEM)、X射线衍射仪及UTM4304电子万能试验机分析测试了镁基复合材料的组织结构,相组成及力学性能。结果表明,SiC颗粒增强镁基复合材料主要由α-Mg和Mg2Si相组成,SiC镀Cu后能够进一步细化晶粒,同时在Mg2Si相周边出现层片状的α+β相。SiCp/AZ91D和Cu-SiCp/AZ91D复合材料的力学性能显著高于AZ91D基体合金,Cu-SiCp/AZ91D复合材料的的抗拉强度达195.7 MPa。室温拉伸时,AZ91D合金表现为典型的脆性断裂特征,而SiCp/AZ91D和Cu-SiC/AZ91D复合材料表现为韧性断裂及部分准解理断裂。     

Be和Y对AZ91D压铸镁合金组织的影响

以AZ91D为基体,研究了添加Be和Y对其压铸组织的影响。结果表明,加入Be,AZ91D合金组织中析出了Mg_(3.1)Al_(0.9)、Mg_2A_(l3)和Mg_(17)Al_(12)相。Be含量增加,AZ91D合金α-Mg相枝晶得到细化,有球化趋势。Y也可显著细化α-Mg基体,并细化β-Mg_(17)Al_(12)相;随Y含量的增加,压铸AZ9D合金组织得到逐步细化,相组成为α-Mg、Mg_(0.97)Zn_(0.03)和Mg_(3.1)Al_(0.9)。     

热处理对挤压铸造n-SiC_p/AZ91D镁基复合材料组织和力学性能的影响

采用金相、X射线衍射、扫描电镜(SEM)、拉伸试验等方法分析和测试了挤压铸造纳米Si C颗粒增强AZ91D镁基复合材料在铸态(F)、固溶态(T4)和人工时效态(T6)下的组织和力学性能。结果表明,固溶处理可使n-Si Cp/AZ91D铸态组织中的β-Mg17Al12共晶相溶入到基体中,形成单一的过饱和α-Mg固溶体,合金抗拉强度和伸长率均有大幅提高,分别达到265 MPa和13.7%;经时效处理后,复合材料的抗拉强度和屈服强度进一步提高,分别为275,145 MPa;SEM结果显示,β-Mg17Al12相主要以连续析出/非连续析出方式分别在晶内及晶界上析出,特别是纳米Si C颗粒分布对二次析出相β-Mg17Al12的形貌、尺寸、分布有一定的影响,使二次析出相变得细小和弥散分布,从而充分发挥了二次析出相的沉淀强化作用;最后对n-Si Cp/AZ91D复合材料不同热处理条件下的断口形貌进行了SEM观察,并且对其断裂方式进行了分析和讨论。     

Al2O3颗粒增强AZ91D镁基复合材料的研究

以平均颗粒尺寸为30nm的Al2O3颗粒作为增强相,采用全液态搅拌铸造法制备了Al2O3/AZ91D复合材料。通过光学显微分析、XRD衍射分析、SEM扫描和EDS能谱分析、硬度测试等检测手段对复合材料的显微组织和性能进行了研究。研究结果表明:由于初生相α-Mg在Al2O3颗粒表面非均质形核及Al2O3颗粒阻碍α-Mg相生长的双重作用使Al2O3/AZ91D复合材料的晶粒得到了明显细化,而且复合材料的硬度明显高于AZ91D合金,并随着Al2O3颗粒加入量的增加,其复合材料的硬度不断提高。     

Y和Gd对消失模铸造AZ91D镁合金组织和性能的影响

为改善消失模铸造AZ91D镁合金的显微组织和力学性能,在合金中加入稀土元素Y和Gd。结果表明:Y和Gd在消失模铸造AZ91D镁合金中生成块状的Al2Y和Al2Gd相,细化基体组织,并使β-Mg17Al12相形貌由网状转变为断续状和颗粒状。Y和Gd的加入提高了消失模铸造AZ91D镁合金中α-Mg的初晶析出温度,降低其共晶温度。适量的Y和Gd能显著提高消失模铸造AZ91D镁合金的力学性能,当Y和Gd的含量分别为0.6%和0.9%时,抗拉强度、伸长率和硬度达到最大,分别为161.68MPa、2.80%、HB64.7,比不加Y和Gd的AZ91D镁合金分别提高了18.8%、54.7%、19.2%。     

快速凝固AZ91D镁合金组织的研究

用光学显微镜和透射电镜观察了普通凝固和快速凝固AZ91D合金的组织，用X射线衍射XRD分析了合金的相组成。结果表明，普通凝固AZ91D合金组织由α-Mg基体和β-Mg1，Al12相组成，晶粒较粗大，而快速凝固AZ91D合金薄带截面组织由靠近辊面的粗大等轴晶区、中部的柱状晶区和自由表面层的细小等轴晶区三部分组成，三层组织均为过饱和α-Mg固溶体，并观察到较高的位错密度。     

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.     

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.     

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.     

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.