激光熔覆CoCrCu0.4FeNi高熵合金涂层的微观组织和性能

目的 提高零部件的硬度和耐磨性。方法 采用Ni-Cr-B-Si、Co-Cr-B-Si自熔合金以及Cu粉在Q235钢基体上激光熔覆CoCrCuFeNi高熵合金涂层,激光功率为2.2、2.4 kW,扫描速度为9、12 mm/s,利用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析涂层的微观组织,并测试了涂层的显微硬度。结果 Cu含量较高的涂层与基体形成了良好的冶金结合,但在涂层中存在严重的Cu偏析现象;Cu含量较低的涂层与基体结合处附近存在少量孔洞缺陷,局部区域具有调幅分解,涂层微观组织主要由树枝晶和枝晶间组成,树枝晶为FCC1,富Cu贫Cr,枝晶间为FCC2,富Cr贫Cu,还存在少量的纳米相,形成了具有C和B间隙固溶的CoCrCu_0.4FeNi高熵合金涂层。熔覆的涂层厚度为2.19～2.58 mm,涂层枝晶厚度为2.2～7.3μm,且枝晶越小,硬度越高。涂层的显微硬度为280～300HV0.2,基体的硬度为110～130HV0.2,约为基体的2.5倍。结论 采用Ni-Cr-B-Si、Co-Cr-B-Si自熔合金和Cu粉激光熔覆了CoCrCuFeNi高...     

Q235钢等离子熔覆CoCrCuFeMnNi高熵合金涂层

在Q235钢基体上采用等离子弧熔覆法制备了CoCrCuFeMnNi高熵合金涂层。采用SEM、EDS、XRD等研究了涂层的组织,利用显微硬度计测试了涂层的显微硬度分布。结果表明：采用等离子熔覆等摩尔Co、Cr、Cu、Fe、Mn、Ni单质金属混合粉,形成了无裂纹、无孔等与基体冶金结合的高熵合金涂层。涂层厚度约为1mm,主要由FCC1固溶体枝晶和少量枝晶间组织组成,枝晶间为BCC、FCC2相。涂层的显微硬度大约为260～390 HV0.2,明显高于基体的硬度150～180 HV0.2。     

等离子熔覆制备AlCrFeMnNi高熵合金涂层的微观组织与性能EI北大核心CSCD

对高熵合金涂层的成分设计已有较多探究,但针对无Co系高熵合金涂层研究较少。采用等离子熔覆技术在E32钢上制备AlCrFeMnNi高熵合金涂层,利用金相显微镜、SEM、EDS、XRD等对涂层的组织形貌、相结构及元素分布等进行观察分析,采用显微硬度计、电化学工作站、XPS表征涂层的硬度分布及耐腐蚀性能。结果表明,等离子熔覆制备的高熵合金涂层无裂纹、气孔等宏观缺陷,涂层为BCC结构;涂层平均硬度为411.6 HV0.5,为基体硬度的2倍以上;在质量分数3.5%的NaCl溶液中涂层的自腐蚀电位为-0.35V,自腐蚀电流密度为507 nA/cm^(2),基体的自腐蚀电位为-0.92V,自腐蚀电流密度为256μA/cm^(2),涂层的自腐蚀电位和极化电流密度较基体有大幅度提升,涂层的固溶强化作用和晶格畸变作用以及BCC结构的螺旋位错强化是提升涂层硬度的原因,均匀的元素分布和致密的钝化膜是其耐蚀性好的主要原因。通过等离子熔覆技术得到高强度、耐腐蚀性好无Co系高熵合金的涂层,可对易制备、低成本的高熵合金涂层的开发、制备和应用提供一定的技术支持。     

熔覆电流对AlCrFeCoNiCu高熵合金涂层显微组织的影响

采用氩弧熔覆工艺在06Cr19Ni10钢基体上制备等摩尔比AlCrFeCoNiCu高熵合金涂层。采用10%草酸溶液体系对不同熔覆电流制备的高熵合金涂层进行电解腐蚀,采用倒置金相显微镜观察试样显微组织,采用3D激光共聚焦显微镜对高熵合金涂层中的细小析出物进行微区三维显微形貌分析,并采用自动转塔显微硬度计对其截面显微硬度进行分析。结果表明,以不同熔覆电流制备的AlCrFeCoNiCu高熵合金涂层均由枝晶组织、枝晶间组织、块状析出物以及纳米级析出物组成。以240 A熔覆电流制备的涂层由于热输入过大,过热粗化的枝晶组织在凝固过程中发生臂端部位的熔解。240 A熔覆电流制备的熔覆涂层的表面硬度达到最高,但截面硬度较低。230 A熔覆电流制备的熔覆涂层的表面硬度、截面硬度均较理想。     

熔覆电流对FeCoCrNiMn高熵合金涂层组织与性能的影响

目的 研究等离子熔覆电流对FeCoCrNiMn高熵合金涂层组织与性能的影响。方法 采用等离子堆焊工艺在65Mn钢基体上制备等摩尔比的FeCoCrNiMn高熵合金涂层。通过观察涂层的宏观表面特征来判断等离子熔覆技术制作高熵合金涂层的宏观效果。利用金相显微镜（OM）、扫描电镜（SEM）以及X射线衍射技术（XRD）观察涂层显微组织,并分析涂层的成分和相组成。采用维氏硬度显微测试计测量合金涂层的表面硬度和基体至涂层的层深硬度。结果 等离子熔覆技术制备的合金涂层无裂纹,涂层平均厚度达到2 mm。涂层元素与熔覆粉末元素比例一致,除去部分Fe元素由基体进入涂层之外,涂层依旧为单相FCC固溶体结构,组织形态为枝晶。涂层与基体结合处可以观察到明显的柱状晶区和热影响区（HAZ）。随着电流的增大,枝晶组织逐渐变粗,而FeCoCrNiMn高熵合金涂层的表面硬度逐渐减小,在190 A处,硬度发生突变达到最大值366.3HV,170 A处为最小值258.78HV。沿层深方向,涂层硬度变化不大,热影响区内由上到下,硬度先增大后减小。结论 等离子熔覆技术制备高熵合金涂层有明显的优势,且具有制作大面积表面涂层的潜力,涂层厚度可以达到毫米级。电流大小改变,FCC相组成没有发生改变,而组织结构发生改变,随着电流变大,枝晶组织变粗,涂层硬度逐渐下降。     

激光熔覆CoCrFeNiSix高熵合金涂层组织及耐蚀性能研究

目的 研究Si含量对CoCrFeNi系高熵合金涂层组织、物相、显微硬度及耐蚀性能的影响.方法 通过激光熔覆技术在45钢基材上制备CoCrFeNiSix(x为物质的量之比,x=0.0,0.5,1.0,1.5,2.0)高熵合金涂层,使用扫描电镜、X射线衍射仪、显微硬度仪、电化学工作站对涂层的显微组织、物相组成、显微硬度、耐蚀性能、腐蚀形貌进行分析研究.结果 CoCrFeNi高熵合金涂层为单一的fcc相,之后随着Si含量的提升,涂层向bcc相转变,当x=2.0时,全部转化为bcc相.涂层的微观组织以等轴晶与枝晶为主,当Si含量较少时,Si元素主要在晶界中偏析,随着Si含量的增加,过多的Si会固溶到晶粒内部.涂层的平均显微硬度随着Si含量的升高而增加,CoCrFeNiSi2.0可达到566.5HV0.5.在3.5％NaCl溶液中,涂层的腐蚀电位随Si含量的增加而变大,CoCrFeNiSi2.0较CoCrFeNiSi0.0的腐蚀电位正移约160 mV,腐蚀电流密度从1.17×10-6 A/cm2减小到6.06×10-7 A/cm2,耐蚀性提高.当Si含量较低时,涂层表面出现连续大面积腐蚀痕迹,随着Si含量的增加,表面腐蚀以点蚀为主.结论 在CoCrFeNi系高熵合金涂层中添加Si元素,可以促进bcc相的生成,提高涂层的显微硬度,同时可以有效抑制合金涂层的腐蚀倾向,以及减缓合金涂层的腐蚀速率,提高耐蚀性能.     

铬铁原矿粉激光制备高熵合金复合涂层的组织与性能

目的用铬铁原矿粉快速直接制备高熵合金复合涂层,研究其组织结构及性能,提高基体表面硬度和耐磨性。方法采用激光熔覆技术在40Cr钢表面制备高熵合金复合涂层,运用金相显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)及硬度计、磨粒磨损机,分析高熵合金复合涂层不同深度的显微组织、物相结构及力学性能。结果高熵合金复合涂层与基体结合良好,物相结构为简单BCC结构的过饱和固溶体,显微组织为典型胞状和树枝晶组织,且原位自生形成的细小碳化物颗粒强化相弥散分布于基体。深度为0.1 mm时,复合涂层的显微组织形貌最细小,且存在一定程度的成分偏析。复合涂层显微硬度平均为6.48 GPa,为基材40Cr钢的2倍以上。高熵合金复合涂层不同深度的磨损率均低于基体的磨损率,且随着深度的增加,磨损率逐渐升高,当深度为0.1 mm时,磨损率最低,为0.17 mg/mm2,耐磨性最好。结论以铬铁原矿粉为掺杂组元,采用激光熔覆技术成功制备出掺杂原位自生颗粒强化相的高熵合金复合涂层,显著提高了基体表面硬度和耐磨性。     

退火对激光熔覆CoCrFeNiB_(0.5)高熵合金涂层组织与电化学性能的影响

采用激光熔覆在45钢基体上制备了CoCrFeNiB_(0.5)高熵合金涂层,研究了不同退火温度(700、900、1100℃)对涂层组织及性能的影响。结果表明,涂层激光熔覆态相组成主要为fcc相+少量bcc相,显微组织主要为枝晶组织;退火后,相组成转变为fcc+bcc+M_xB的混合相结构;700℃退火后,枝晶略有粗化,更高温度退火使枝晶断开,枝晶组织逐渐消失;1100℃退火后出现明显的颗粒化、球化相组织;激光熔覆涂层显微硬度较高,最高达到603 HV;700、900℃退火后,由于第二相析出强化,涂层显微硬度略有提高,但1100℃退火后涂层显微硬度下降;CoCrFeNiB_(0.5)涂层具有较高的腐蚀电位与较低的腐蚀电流密度,耐腐蚀性能明显优于45钢;1100℃退火后,3.5%NaCl溶液中腐蚀电流密度比45钢基体低3个数量级,具有较好的耐腐蚀性能。     

熔覆电流对CoCrFeNiMo高熵合金涂层组织与耐磨性的影响

为了探索制备工艺对高熵合金涂层组织与性能的影响,利用氩弧熔覆方法在Q235钢表面制备了等摩尔比CoCrFeNiMo高熵合金涂层.采用光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等研究了涂层的组织形貌及物相,采用显微硬度计和摩擦磨损试验机分析了涂层的硬度和耐磨性.结果 表明:采用氩弧熔覆方法能成功在Q235钢表面制备出厚度在2 mm以上的CoCrFeNiMo高熵合金涂层;靠近涂层顶部,熔覆电流对涂层的组织影响明显;随着熔覆电流的增加,涂层中上部过渡区组织由胞状晶向枝状晶和等轴晶转变,同时出现晶粒细化现象,BCC、FCC两相固溶体逐渐转变到BCC单相固溶体.随熔覆电流的增加,涂层的硬度和耐磨性均先升高后降低,涂层表层硬度最大,向基体方向呈下降趋势.当熔覆电流为200 A时,涂层的表层硬度最高,达626.7 HV0.2,约为Q235基体的4倍,其耐磨性也最好.涂层的磨损机制主要为粘着磨损,熔覆电流为200 A制备的涂层伴随有磨粒磨损.     

熔覆电流对氩弧熔覆FeCrNiCoMn高熵合金涂层组织及显微硬度的影响

采用氩弧熔覆工艺在Q235基体上制备了等摩尔比FeCrNiCoMn高熵合金涂层,采用倒置金相显微镜、自动转塔显微硬度计及3D激光共聚焦显微镜对高熵合金涂层组织及显微硬度进行了分析。结果表明,不同熔覆电流下,FeCrNiCoMn高熵合金涂层均主要由枝晶组织和枝晶间组织组成,且其枝晶间组织中均生成了大量纳米级的析出物。在180~190 A范围内,随熔覆电流的增大,组织显著细化,且枝晶间组织中纳米级析出物形状规则,分布均匀;熔覆电流增大至200 A,涂层组织过度粗大,枝晶间组织被破坏,枝晶间组织中纳米析出物形状、分布均不理想。不同熔覆电流下,FeCrNiCoMn高熵合金涂层表面显微硬度差别不大。180、190 A熔覆电流制备的涂层比200 A熔覆电流制备的涂层截面显微硬度分布更理想。     

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.