B和Si掺杂对CrAlN涂层结构和切削钛合金寿命的影响

目的 CrAlN涂层以其优异的抗氧化性能被广泛应用于切削刀具涂层领域，针对CrAlN涂层热稳定性较低，在超过900 ℃后会发生热分解，导致其力学性能显著下降的问题，通过B、Si共掺杂方法改善CrAlN涂层的性能。方法 采用阴极弧蒸发方法制备Cr0.42Al0.58N、Cr0.35Al0.59B0.06N、Cr0.37Al0.54Si0.09N涂层，借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)、纳米压痕仪，通过划痕和切削实验研究B和Si掺杂对CrAlN涂层晶体结构、硬度、结合力、热性能和切削寿命的影响。结果 Cr0.42Al0.58N和Cr0.35Al0.59B0.06N涂层为单相立方结构，Cr0.37Al0.54Si0.09N涂层为立方和六方的两相结构;Cr0.42Al0.58N、Cr0.35Al0.59B0.06N、Cr0.37Al0.54Si0.09N涂层的硬度分别为(29.8±1.5)、(36.9±1.4)、(33.8±1.6)GPa，与基体的结合力分别为116.2、58.3、58.0 N;通过B和Si掺杂抑制了CrAlN涂层的热分解过程，Cr-N键的断裂起始温度由Cr0.42Al0.58N的1 000 ^oC提高到Cr0.35Al0.59B0.06N的1 200 ℃和Cr0.37Al0.54Si0.09N的1 100 ℃;在1 100 ℃下氧化15 h后，Cr0.42Al0.58N、Cr0.35Al0.59B0.06N、Cr0.37Al0.54Si0.09N涂层的氧化层厚度分别为2.38、1.80、0.53 μm。结论 通过B和Si掺杂提高了CrAlN涂层的力学性能、热稳定性和抗氧化性，其中CrAlBN涂层呈现出最优异的热稳定性和切削性能，CrAlSiN涂层的抗氧化性最佳。     

热处理对碳化硅基复合材料结构与力学性能的影响

碳化硅纤维增强碳化硅复合材料(Si C/Si C)是极具前景的高温结构材料。通过先驱体浸渍裂解(PIP)工艺制备了Si C/Si C复合材料。在惰性气氛下,1400~1800℃范围内对Si C/Si C复合材料进行热处理,用红外热像仪作为测温工具监测材料温度,研究了热处理温度对Si C/Si C复合材料结构和力学性能的影响。结果表明,经1400℃热处理后复合材料基体结晶程度增加,整体力学性能提高;随热处理温度进一步提高,复合材料纤维受损,力学性能急剧下降。     

Cr_2AlC陶瓷粉体的无压烧结及表征

本文以Cr、Al和C粉为原料,采用无压烧结合成了纯相的Cr_2AlC粉体。研究了烧结温度对合成物相的影响,得出最佳烧结温度为1400℃。分析反应路径,发现Al先熔化成Al液,同时引发Cr和Al反应生成Cr2Al及少量Cr_2AlC。Cr-Al金属间化合物再与C和Al发生反应最终合成Cr_2AlC。掺杂Si元素后发现Cr_2AlC晶格常数变化,说明Si固溶到Cr_2AlC当中。     

MgO-C耐火材料中陶瓷相的原位生成机理及其对材料力学性能的影响

以电熔镁砂、鳞片石墨以及Al-Mg合金粉、金属Si粉为原料,以Ni(NO_3)_2·6H_2O为催化剂,以酚醛树脂为结合剂,在经配料、混合、成型后,分别在1200、1400℃埋炭条件下进行热处理制备了MgO-C耐火材料。研究了不同催化剂添加量对Mg O-C耐火材料物相组成、显微结构特征和试样抗热震及力学性能的影响。结果表明:经1200℃热处理后,试样中Al-Mg合金被氧化,进一步反应生成镁铝尖晶石;经1400℃热处理后,Si单质消失,试样中有Si C生成,镁铝尖晶石生成量增加,并且有Al N相生成;当催化剂加入量分别为0.4%、0.6%时,试样基质中可原位生成镁铝尖晶石晶须,Si C及Al N等陶瓷相,试样的抗热震性能和断裂韧性都得到提高。     

铜、锌含量对铝合金挤压铸造力学性能的影响

在ZL102铝硅合金中分别加入3%Cu、11%Zn以及同时加入3%Cu和11%Zn后进行了挤压铸造工艺试验,并对其力学性能、显微组织、断口形貌进行了对比分析研究。结果发现,Al7Si3Cu合金的最佳工艺方案为:模具预热温度200℃,浇注温度700℃,压力140 kN,保压时间12 s;Al7Si11Zn合金的最佳工艺方案为:模具预热温度200℃,浇注温度680℃,压力100 kN,保压时间10 s;Al7Si11Zn3Cu合金的最佳工艺方案为:模具预热温度200℃,浇注温度700℃,压力140 kN,保压时间12 s。试验结果表明,向Al7Si3Cu合金中加入11%的Zn,使其抗拉强度提高了14.7%,硬度提高了35.6%;Al7Si11Zn合金中加入3%的Cu,虽然硬度提高了11.6%,但是抗拉强度下降了20.2%;Al7Si11Zn合金比Al7Si3Cu合金的平均抗拉强度高44.5%,平均硬度高21.5%。     

钼基掺杂合金的研究现状

合金化是改善钼性能的主要途径。本文对固溶强化类、弥散强化类及K泡强化类钼合金进行了综合评述,重点从制备方法、形貌组织、强化机理以及力学性能这几个方面,对TZM合金、Mo-Re合金、La2O3掺杂钼合金、Al2O3掺杂钼合金以及Si-Al-K掺杂钼合金这几类合金的研究现状进行了分析。根据钼合金抗氧化性能差和耐磨性能差这两个缺点,提出了研制抗氧化涂层和硬质相是未来钼合金发展的两个重要方向。     

超声处理对Al-Si活塞合金组织和力学性能的影响

对不同温度的Al-12Si-4Cu-Mg-2Ni活塞合金熔体进行了超声处理,研究了超声处理温度和超声功率对合金显微组织和力学性能的影响。结果表明,超声处理细化了初生Si、共晶Si,提升了合金力学性能。熔体温度为720℃时的细化效果优于650℃和690℃。熔体温度为720℃,超声功率为0~1400W时,初生Si的平均等积圆直径从40.73μm减小到23.35μm;共晶Si的平均长度从39.6μm减小到27.1μm;第二相的形态未发生改变;与未超声处理相比,合金的室温抗拉强度和350℃高温抗拉强度分别提高了21.9%和22.8%。     

热处理工艺对增材制造AlSi10Mg合金组织与力学性能的影响

对比研究了增材制造Al Si10Mg合金与传统铸造ZL104合金的化学成分、组织与力学性能,研究了退火温度、退火时间对增材制造Al Si10Mg合金组织与力学性能的影响。结果表明,当对增材制造Al Si10Mg合金进行T1(180℃×12 h,空冷)和T2(230～250℃×2 h,空冷)处理时,力学性能满足R_m≥380 MPa,A≥8%的要求。     

固溶处理对准共晶Al-Si合金显微组织及力学性能的影响

通过金相显微镜、差示扫描量热分析以及显微硬度测试等研究固溶温度和固溶时间对挤压铸造的ZAlSi12CuMgNi铝合金的显微组织和力学性能变化的影响。结果发现:在固溶过程中,强化相逐渐溶解,共晶Si逐渐细化、弥散,块状初晶Si趋于圆整化;保温时间过长,细化后的Si会发生聚集、粗化、长大,块状Si圆整度下降以及α(Al)晶粒长大等现象;随着固溶温度的上升,强化相的溶解和Si相的粒化、圆整化的时间会缩短,且Si相的细化程度和弥散程度更高,而Si相粗化和α(Al)晶粒长大的速度也会增大;在不同固溶温度下,α(Al)固溶体的力学性能随保温时间的延长而呈现不同形式的下降趋势;挤压铸造的ZAlSi12CuMgNi铝合金的最佳固溶处理工艺为525-530℃,保温时间为2.5-3h。     

退火工艺对MHC钼合金板材组织和力学性能的影响

采用粉末冶金工艺制备了MHC钼合金板材,通过拉伸力学性能测试、硬度测试、金相分析等测试手段,研究了退火温度对MHC钼合金板材显微组织和力学性能的影响。结果表明:轧制后的MHC钼合金板材的纵向抗拉强度为1150 MPa,规定塑性延伸强度为1020 MPa,伸长率为10.5%,维氏硬度为352 HV10。MHC钼合金板材在1400℃开始发生再结晶,到1700℃发生了完全再结晶,其抗拉强度和硬度均随退火温度的升高而降低,在1300~1500℃范围内伸长率随退火温度的升高而升高,在1500~1700℃范围内伸长率随温度的升高而降低,在1500℃的伸长率最高,达到22.5%。     

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.     

A Concordant Shift Model for Flow in Bulk Metallic Glasses

The homogeneous plastic flow in bulk metallic glasses(BMGs) must be elucidated by an appropriate atomistic mechanism. It is proposed that a so-called concordant shifting model, based on rearrangements of five-atom subclusters,can describe the plastic strain behaviour of BMGs in a temperature range from room temperature to the supercooled liquid region. To confirm the effectiveness of the atomic concordant shifting model, a comparative investigation between the vacancy/atom model and the concordant shifting model is carried out based on the estimation of the strain rate deduced from two models. Our findings suggest that the atomic concordant shifting model rather than the vacancy/atom exchange model can well predict the large strain rate in the superplasticity of BMGs.