Cu-15Cr-0.1Zr原位复合材料的组织与性能

采用冷变形+中间热处理方法制备Cu-15Cr-0.1Zr原位复合材料.这种Cr纤维原位强化复合材料的强度为1200 MPa,导电率为73%IACS.研究了不同应变量下材料的微观组织演变和力学性能.随应变量的增加,强度增加,Cr相形态由枝晶演变为细小丝带状.研究不同中间退火工艺对材料性能的影响,结果表明,通过冷变形及适当的中间热处理可获得强度和导电率的较好组合.     

形变Cu-15%Cr原位复合材料的组织和力学性能

通过冷变形拉拔结合中间热处理制备了纤维相增强的Cu-15wt%Cr合金,研究了变形过程对组织形态和力学性能的影响.用SEM观察分析了材料的组织结构.研究表明,通过形变原位复合技术,可以获得抗拉强度大于1000MPa,导电率大于71%IACS的形变Cu-15wt%Cr原位复合材料.通过控制形变量以及调整中间热处理和稳定化热处理规范,可以获得不同强度和导电率的组合.形变量越大,纤维越均匀细化.力学性能和电阻率测试结果表明,随形变量增加,强度提高,同时电阻率增大.     

某些因素对Cu-Ag合金原位复合材料的结构和性能的影响

制备了具有不同Ag含量的Cu-Ag合金及其原位纤维复合材料,增加Ag含量可以细化铸态组织和Ag纤维尺寸,增大合金的极限拉伸强度和电阻率.但当Ag含量＞20%,这种对组织细化和性能影响的趋势减小.研究了凝固条件、微量稀土添加和中间热处理等冶金学因素对低Ag含量的Cu-Ag合金及其原位纤维复合材料的结构和性能的影响,获得了具有拉伸强度σb＞1.5GPa和导电率γ＞60%IACS的Cu-Ag合金原位纤维复合材料.讨论了大变形Cu-Ag合金原位纳米纤维复合材料所显示的两阶段应变强化效应及其机制.     

不同凝固条件制备的Cu-Ag合金原位纤维复合材料的结构与性质

以冷却速率10^1～10^3K/s的不同凝固务件制备了Cu-10Ag合金及其原位纤维复合材料。研究了铸态和形变态合金的结构与性能。铸态合金的结构由Cu相、Ag沉淀相和(Cu Ag)共晶组成。通过大变形发展为Cu—Ag合金原位纳米纤维复合材料，其中由Ag沉淀相所形成的Ag纤维尺寸(d)与真实应变(η)呈指数函数关系：d=C.exp(-0．228η)，(Cu Ag)共晶中Ag层转变为更细的纳米Ag纤维。Cu—Ag合金原位纳米纤维复合材料显示了两阶段应变强化效应：在低真实应变阶段主要表现为加工硬化或位错强化，在高真实应变阶段主要表现为超细Ag纤维强化或界面强化。快速凝固的Cu—Ag合金原位纳米纤维复合材料比慢速凝固材料具有更高的包括极限拉伸强度和电导率在内的综合性能。在形变过程中复合材料的强度与电导率的演变出于相同的结构原因。     

大变形Cu-10Ag原位纳米纤维复合材料

以不同的凝固速率制备了Cu-10Ag亚共晶合金。铸态结构由初生Ag沉淀,(Cu+Ag)共晶和Cu相组成。采用大变形制备了Cu-10Ag合金原位纤维复合材料。其中由初生Ag沉淀相所形成的Ag纤维具有较大直径(d)并可用幂指数关系d=C·exp(-0.228η)拟合,式中η是真实应变,C是与合金原始晶体尺寸有关的系数,而由(Cu+Ag)共晶中的Ag层所形成的Ag纤维具有更细直径(几纳米)。低温中间热处理可进一步细化Ag纤维尺寸和改进性能。经热机械处理的Cu-10Ag合金原位纳米纤维复合材料具有高强度(σb＞1.5 GPa)和高电导率(＞60％IACS)。大变形Cu-10Ag合金原位纳米纤维复合材料显示了两阶段强化效应。讨论了影响Ag纤维尺寸的因素和复合材料的强化与形变机制。     

形变Cu-10Fe-1Ag原位复合材料的组织和性能

采用大气熔铸与形变原位复合的方法制备了形变Cu-10Fe-1Ag原位复合材料.测定了不同应变量下材料的抗拉强度和导电率;用SEM观察分析了材料的显微组织;用EDS分析了Fe和Ag在铜基体中的分布.结果表明,形变Cu-10Fe-1Ag原位复合材料采用合适的变形量和中间退火工艺,可以获得强度和导电率较好的结合.当应变量为6.7时,抗拉强度达到913 MPa,导电率达到51%IACS.     

大变形Ag-10Cu原位纤维复合材料的应变强化效应

利用热挤压加冷拉拔制备Ag-10Cu原位纤维复合材料。Ag-10Cu合金铸态及挤压态结构由Ag基体、(Ag+Cu)共晶体和Cu沉淀组成。经大变形后变成Ag基体加Cu纤维的两相组织,合金中的Cu相转变成Cu纤维,其尺寸d随拉拔应变η呈幂指数关系变化,且可拟合为d=d0exp(-0.144η),其中d0是与Cu沉淀初始尺寸有关的系数。讨论了材料强度的两个阶段变化及其强化机制。所制备的材料可以达到抗拉强度接近1GPa及电导率大于60%IACS的较优性能组合。还讨论了中间热处理的影响。     

大变形Cu-Ag合金原位纤维复合材料的稳定性

制备了Cu-10Ag和Cu-10Ag-0.05Ce合金,其铸态结构由Ag沉淀、(Cu Ag)共晶和Cu基体组成.采用大变形法制备了两合金的原位纳米纤维复合材料.研究了大变形(真应变ε≥9)合金和时效态合金的结构与性能,观察了Ag沉淀过程.结果表明微量Ce添加剂细化Ag纤维尺寸,提高再结晶温度和不连续沉淀的温度,明显提高形变态、时效态和完全退火态Cu-10Ag合金的拉伸强度,而保持与Cu-10Ag合金相近或相当的导电率.真实应变ε=9.9的大变形Cu-10Ag和Cu-10Ag-0.05Ce合金的抗拉强度分别为1 190和1 430 MPa,导电率分别为68.7%和67.6%IACS,这些性能在低于300℃是稳定的.     

Cu-Cr-Zr原位复合材料的组织与性能

采用真空熔铸与形变相结合的方法制备高强高导Cu-Cr-Zr原位复合材料,利用SEM和TEM分析材料在铸态及变形态的显微组织,研究不同变形量和中间热处理对Cu-Cr-Zr原位复合材料的抗拉强度和导电率的影响。结果表明:Cu-Cr-Zr合金经室温冷变形,Cr相由铸态树枝状转变为纤维状;中间热处理能够明显提高材料的导电率;采用500℃中间热处理并结合冷变形,能得到具有较好综合性能的Cu-Cr-Zr原位复合材料,其抗拉强度达到1119MPa,导电率(vsIACS)达到76%。     

时效处理对形变Cu-10Fe-3Ag原位复合材料组织及性能的影响

采用大气熔炼与形变原位复合的方法制备形变Cu-10Fe-3Ag原位复合材料。在不同温度时效6 h后,用SEM观察分析材料的显微组织;用XRD测定晶面间距的变化,分析合金元素Ag在时效过程中的行为规律和作用机制。结果表明:Ag能够促进γ-Fe在Cu基体中的时效析出,同时降低Fe纤维的热稳定性;随着时效温度的升高,形变Cu-10Fe-3Ag复合材料的硬度和导电率都是先增加后降低,在475℃时效6 h后,导电率达到58.4%IACS。合金的断口全是韧性断裂,随着时效温度的升高,韧窝变小。     

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.     

Bulletin of the Awards in 2013

<正>Five reviewers and 9 published articles are selected as the Excellent Rewewerand Excellent Article in 2013 respectively.Excellent Reviewers:Prof.Z ongyi Ma(Institute of Metal Research,CAS,C hina);Prof.Y ongbo Xu(Institute of Metal Research,CAS,C hina);Prof.Guangping Zhang(Institute of Metal Research,C AS,C hina);Prof.Z hendui Cui(Tianjin University,China);