等通道转角挤压对LA141镁锂合金显微组织及力学性能的影响

采用等通道转角挤压(ECAP)工艺在室温下对LA141镁锂合金进行了1～4道次挤压变形。对变形合金进行了物相分析、显微组织观察、扫描电镜分析以及室温拉伸试验,研究了ECAP挤压工艺对LA141镁锂合金显微组织及力学性能的影响。结果表明:随着ECAP挤压道次的增加,合金中粗大的晶粒在剪应力作用下沿挤压方向被拉长而形成带状组织,剪切带变得更加细小并趋于均匀分布;与原始态试样相比,挤压后试样的拉伸强度和伸长率均有不同程度的提高,挤压后拉伸断口呈韧窝状,随着挤压道次的增加,韧窝尺寸减小,韧窝数量增多,塑性增加。     

ECAP变形对Mg-Y-Nd-Zr合金组织和性能的影响

利用等通道角变形(ECAP)方法,沿Bc路径在400℃温度下对稀土Mg-2Y-0.6Nd-0.6Zr合金进行不同道次的塑性变形,采用光学显微镜,X射线衍射仪和电子背散射衍射(EBSD)技术等分析了不同道次挤压之后合金的微观组织、晶粒尺寸、物相和织构的变化,采用硬度试验和拉伸试验研究了ECAP不同道次对合金力学性能的影响。结果表明:ECAP之后Mg-2Y-0.6Nd-0.6Zr合金晶粒得到明显细化,并且在4道次之后晶粒细化效果最佳,大部分晶粒已细化至0.45μm;在ECAP变形6道次后再结晶的晶粒开始长大,但晶粒组织在6道次的时候均匀性最好;Mg-2Y-0.6Nd-0.6Zr合金第二相体积分数较小,ECAP变形后有大量的第二相粒子Mg_2Y相从过饱和的基体中析出且多分布于晶界处,ECAP变形4道次后各相数量趋于稳定;Mg-2Y-0.6Nd-0.6Zr合金随着挤压道次的增加,小角度晶界所占比例减少,大角度晶界有所增加;同时,进行ECAP变形后,Mg-2Y-0.6Nd-0.6Zr合金织构的强度和取向都有所变化,织构强度在4道次时最弱,在随后的ECAP变形中又开始增强,在6道次时由倾斜织构转变成强基面织构,Schmind因子趋于0,力学性能结果表明晶粒的细化作用大于织构的软化作用和强化作用,随着ECAP道次的增加,Mg-2Y-0.6Nd-0.6Zr合金的力学性能有所提高,但是在ECAP变形4道次后提高幅度较小,抗拉强度由150 MPa提高到183 MPa,硬度也从54.8 HV0.1提高到了63.7 HV0.1,屈服强度也较ECAP变形之前提高了56%,基本上符合Hall-Petch关系;并且在6道次后,由于晶粒细化且均匀分布,室温伸长率提高到了26.7%。     

ECAP挤压对5083铝合金组织与力学性能的影响

研究了5083铝合金等通道转角挤压(ECAP)的室温拉伸性能.结果表明:5083铝合金经100℃、16道次ECAP挤压后,晶粒明显细化且第二相均匀弥散分布,合金的强度提高至480MPa;200℃、16道次ECAP挤压后,合金强度有所下降(约380MPa),但塑性显著改善(伸长率16％以上);降低ECAP挤压温度、增加挤压道次可获得更高的挤压硬化和细晶强化效果,在100℃ECAP挤压和200℃退火同样可提高该合金的抗拉强度和塑性变形能力.     

12MnNb钢的ECAP变形及组织性能研究

室温下对12MnNb钢进行ECAP变形,累积等效应变达到4.通过光学显微镜、电子拉伸机等试验仪器设备,分析研究ECAP变形试样的显微组织特征及其演变规律,以及力学性能的变化规律.结果表明,C方式ECAP变形时,1道次的组织细化和强化效果最为显著,随后道次主要增加晶粒的取向差.经ECAP变形后,强度随变形道次的增加而增加,4道次后的抗拉强度达到895 MPa,并保持了较好的塑性,伸长率达到12.4%.     

TG6合金等温变形条件下组织演变与性能的研究

采用不同的等温锻造火次和相同的总变形量,改变TG6合金锻件的加热时间和每火次变形量,对该合金等温锻件的显微组织演化与拉伸性能进行研究。结果表明：随等温锻造火次增多,组织中初生α相含量增多,片状次生α相长度和亚β晶粒尺寸先减小后增大,而片状α相的厚度递增。室温和高温拉伸强度随锻造火次的增加呈现先减少后增加的趋势,塑性则先增加后减小。1火次成形时变形量较大,锻件产生温升造成组织中初生α相较少,同时较多且细长的次生α相增加了该锻件的拉伸强度。3火次成形时由于合金中各相再结晶程度不同,使组织中亚β晶界处产生较多细小等轴α相,该相增加了锻件的塑性。5火次锻造时,锻件加热时间较长,造成组织中α相的聚集长大。TG6合金等温锻造多火次成形时,每火次变形量存在一临界范围,处于该范围内每火次锻后空冷时合金发生部分再结晶,形成较为细小的等轴α相,阻碍亚β晶界的迁移,致使亚β晶粒尺寸较小,同时也造成组织中等轴α相尺寸的不均匀     

等通道转角挤压变形Mg-1.5Mn-0.3Ce镁合金的组织、织构与力学性能

采用等通道转角挤压(ECAP)工艺以Bc路径在623K温度下对Mg-1.5Mn-0.3Ce镁合金进行变形,观察显微组织与织构,测试了力学性能。显微组织分析表明,镁合金经ECAP变形晶粒尺寸明显得到细化,经6道次ECAP变形后晶粒尺寸由原轧制态的约26.1μm细化至约1.2μm,且细小的第二相粒子Mg12Ce弥散分布于晶内及晶界处;同时经ECAP变形后,原始轧制织构随变形道次的增加不断减小,并开始转变为ECAP织构,织构强度不断增强;力学性能结果表明,由于晶粒细化作用大于织构软化作用,前3道次ECAP变形镁合金强度随道次的增加不断提高,与Hall?Petch关系相符,在第3道次时其抗拉强度和屈服强度达到最大值,分别为272.2和263.7MPa;在4道次之后形成较强的非基面织构,镁合金强度下降,与Hall?Petch呈相悖关系。断口分析表明,轧制态与ECAP变形镁合金的断裂方式都是沿晶断裂,由于6道次变形镁合金晶粒细化,存在更多的韧窝并获得16.8%最大室温伸长率。     

等通道转角挤压过程中fcc金属的微观结构演化与力学性能

系统总结了面心立方(fcc)金属材料在等通道转角挤压(ECAP)变形后的晶粒细化、微观结构演化规律和力学性能.根据ECAP变形的特点,利用具有特殊取向的Al单晶体和Cu双晶体,经过一道次ECAP挤压发现:材料在ECAP模具对角面附近发生严重塑性变形;除了沿模具对角面切应力的作用外,沿垂直于模具对角面的切应力也起重要作用.此外,通过设计特殊取向的Cu单晶体、Al单晶体和粗晶Cu-3%Si合金经过一道次ECAP挤压,系统研究了层错能、晶粒尺寸和晶体学取向对fcc金属形变孪生所需的孪生应力的影响.对具有不同层错能的Cu-Al合金进行多道次ECAP挤压表明,随着层错能降低,Cu-Al合金的晶粒细化机制逐步从位错分割机制转变为孪生碎化机制,最小晶粒尺寸逐步减小,具有较高或较低层错能材料比中等层错能材料更容易获得均匀的微观组织;Cu-Al合金的拉伸强度和均匀延伸率随着层错能的降低同步提高,即随着层错能的降低,Cu-Al合金的强度-塑性匹配性提高.     

固溶处理对挤压/等温锻复合工艺制备的GH710合金组织与性能的影响

采用光学显微镜、场发射扫描电镜及化学相分析等方法,研究了采用铸锭挤压/等温锻复合工艺制备的GH710合金经不同固溶温度热处理后的显微组织特征、室温拉伸和高温持久性能。结果表明,固溶温度对合金次生MC型碳化物和γ′相的影响显著。随着固溶温度升高,合金的次生MC型碳化物溶解度增大,钉扎晶界作用减弱,晶粒尺寸增大,室温拉伸性能降低;同时,固溶温度升高,使合金一次γ′相减少,二次γ′相增加,增加位错的绕越路径,提高合金持久寿命。为使合金获得良好的室温拉伸和高温性能匹配,固溶温度应控制在1170～1180℃;在标准热处理制度下,合金的抗拉强度达到1332 MPa,伸长率达到11.7%,表现出优异的强度和塑性。     

7475铝合金ECAP变形后的组织和性能

等径弯曲通道变形(简称ECAP)具有获得超细晶组织和改善力学性能的潜力。对7475铝合金在523K和573K下进行了ECAP变形，等效真应变达12左右，ECAP后平均晶粒尺寸约为0．29μm和0．5μm拉伸试验的结果表明：ECAP大大改善了合金的塑性，同时也提高了合金的屈服强度和拉伸强度。     

等通道转角挤压制备超细晶Mg15A1双相合金组织与性能

对高铝双相合金Mg15A1在553K以Bc路线进行了不同道次的等通道挤压（ECAP）,获得了超细晶高铝镁合金。通过OM,SEM,TEM分析了ECAP前后合金的微观组织结构及断口形貌,并测试了不同挤压道次后合金的硬度和室温拉伸性能,分析了ECAP细化晶粒机理及其性能改善原因。结果表明,随挤压道次增加,累计形变增强,网状硬脆相β-Mg17Al12破碎,合金晶粒显著细化,但对单相区和两相混合区细化效果不同。在α、β两相共存区内,4道次ECAP后形成100nm-200nm的细晶粒;在α单相区,4道次ECAP后晶粒为1μm以下,且在初晶α-Mg内析出弥散细小的β相,起到细晶强化和弥散强化作用。8道次ECAP后,晶粒略有长大。ECAP使合金的硬度、抗拉强度和延伸率同时得到提高,尤其是4道次ECAP后,硬度提高了32．04％,抗拉强度σb从150MPa提高到269．3MPa,延伸率δ由0．05％提高到7．4％;8道次ECAP后,硬度、抗拉强度略有下降,延伸率略有上升。SEM断口观察显示ECAP使合金拉伸断口形貌由铸态的解理断裂特征转变为延性韧窝断裂特征。     

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.