机械合金化Cu-Cr粉末的制备及性质研究

采用机械合金化法制备铜铬粉末,研究了不同球磨时间对粉末颗粒结构、晶粒粒度、显微硬度和表面形貌的影响,用XRD、SEM方法表征Cu-15wt%Cr粉末在不同球磨时间下形成固溶体的结构和表面形貌.结果表明:高能球磨形成了铬固溶于铜的过饱和固溶体,随球磨时间的延长,晶粒逐渐细化,点阵畸变愈来愈大,球磨60h后,粉末呈近球形,畸变率为0.271%,显微硬度为349.18HV.     

高能球磨工艺对Cu-10Cr-0.5Al2O3组织与性能的影响

利用高能球磨方法对Cu-10Cr-0.5Al2O3(质量分数,%)混合粉末进行预处理,采用电场活化烧结技术对球磨粉末进行烧结,运用XRD、SEM、硬度、断裂强度和电导率等测试方法研究球磨时间对Cu-10Cr-0.5Al2O3复合粉末烧结前后组织和性能的影响.结果表明随着球磨时间的增加,Cu晶粒更加细化,第二相分布更加弥散,以致烧结材料的强度和硬度逐渐增大,球磨20h后,烧结样品的强度和硬度分别达到952MPa和285HV;由于晶粒细化、高度弥散的第二相以及铜相的晶格畸变加强对电子的散射作用,烧结试样的电导率也随球磨时间的延长而逐渐下降,球磨20h后,烧结样品的电导率下降到51%(IACS).     

高能球磨对3%C-Cu粉末压制特性的影响

针对石墨／铜基复合材料存在烧结膨胀的特点，提出用粉末压制、真空热压烧结和热挤压相结合的致密化工艺。为给后续的烧结提供相对密度较高、质量好的冷压坯，采用刚性模常温单向压制方法研究高能球磨3％C—Cu（质量分数）粉末的压制压力与相对密度的关系，用黄培云压制理论考察球磨粉末的压制特性。用扫描电镜和场发射扫描电镜分别研究高能球磨粉末的微观组织和微区成分。结果表明，压制压力相同时，粉末压坯相对密度随高能球磨时间的延长而逐渐减小。高能球磨时间相同时，粉末压坯相对密度随压制压力的增加而增大。随着高能球磨时间的延长，粉末体越来越难压制。压制压力和保压时间分别为700MPa和30s时，所得粉末压坯的质量较好。     

机械合金化法制备金锡合金

采用高能球磨机械合金化法制备了Au-20%Sn合金,分析了合金物相、组织和硬度随球磨时间的变化规律,探讨了合金塑性与合金组织及制备工艺的关系。结果表明:采用高能球磨机械合金化法可以制备Au-20%Sn合金;随球磨时间的增加,Au-20%Sn的合金化程度增加,组织中的金属间化合物逐渐增多,最终基本上为δ相和ζ′相;合金的硬度随球磨时间的延长逐渐升高,并在球磨60min后获得最高硬度104.2HV,然后开始下降;球磨后的合金粉末在190℃×2h的烧结过程中发生了不同程度的再结晶和晶粒长大,再结晶程度随球磨时间的延长而增加,导致烧结后合金硬度在球磨时间超过60min后反而下降。     

高能球磨纳米Co系催化剂粉末的微观应力

用X-ray法研究了高能球磨制备Co-La2O3和Co-CeO2催化剂纳米粉末过程中Co粉的微观应力与球磨时间的关系,发现两种不同晶型的稀土氧化物对Co粉微观应力的影响不尽相同,掺La2O3的粉末球磨到15h之内时,Co粉的微观应力随球磨时间的增加而增加,但在15-55h这段范围,微观应力随球磨时间的延长而增加的趋势变缓。掺CeO2的Co粉的微观应力在研究时间范围内随球磨时间的增加几乎呈线性增加。     

高能球磨工艺对Ni-Cr-P粉末性能的影响

采用机械合金化方法将Ni-Cr-P粉末用行星式高能球磨机进行球磨,利用SEM、DSC、硬度仪及万能实验机分析了不同球磨时间的粉末和烧结后的试样性能。结果表明:随着球磨时间的延长,粉末的能量在球磨20h达到最高,粉末的形貌图与粉末的能量曲线形成相对应的关系。球磨20h后的试样,在800℃进行烧结,可获得与原始粉末在920℃下烧结时性能相同的试样。     

高能球磨制备Tb_4O_7-TiO_2纳米复合粉末的研究

通过高能球磨技术制备了Tb_4O_7-18Ti O_2(质量分数,%)纳米尺度复合粉末。采用激光粒度测试仪、X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对不同球磨时间的混合粉末的微观形貌组织、颗粒与晶粒大小以及晶格畸变量等进行了研究与表征。结果表明,混合粉末经过高能球磨后其颗粒与晶粒尺寸均达到了纳米级,组织均匀。Tb_4O_7相的X射线衍射峰随球磨时间的增加逐渐宽化且向大角度偏移;Ti O_2相衍射峰强度逐渐降低,在球磨4 h后消失。随球磨时间的增加,颗粒和晶粒的平均尺寸减小,球磨初期减小很快,球磨后期减小缓慢,最后趋于一个稳定值。96 h球磨后颗粒和晶粒的平均尺寸分别为200和95 nm,晶格畸变量达到1.35%。同时探讨了TiO_2相固溶和纳米晶形成原因以及微观组织演变的机制。     

高能球磨对Fe_2O_3粉末形貌和成分的影响

采用行星式高能球磨机对三氧化二铁粉末进行细化球磨,并对不同球磨时间的样品使用XRD和TEM、SEM进行观测,结果发现随球磨时间延长氧化铁颗粒不断细化,但在72h后继续增加球磨时间,并不能使颗粒粒径进一步明显变小.同时在球磨过程中出现了一部分Fe2O3向Fe3O4的转变.     

钼-钴-硅混合粉末的机械合金化研究

采用X射线衍射、扫描电镜及透射电镜研究了配比为Mo5-xCoxSi3(x=0．5，l，2)的混合粉末的机械球磨行为。结果表明：随球磨时间延长，混合粉末中首先形成Co，Si在Mo中的过饱和固溶体Mo(Co，Si)，高能球磨大大扩展了硅和钴在钼中的固溶度。进一步延长球磨时间，过饱和固溶体转变成为非晶。在球磨过程中，Mo(Co，Si)的晶粒不断细化，球磨至40h，晶粒尺寸约为8nm。球磨初期，内应力急剧增加。随球磨时间延长，混合粉末的颗粒尺寸增大，40h后，逐渐减小，且形状球化，100h后成为尺寸不超过100nm的球形粉末。     

高能球磨制备纳米级WC/Cu复合粉末的研究

利用XRD、SEM等分析研究了高能球磨时间对WC／Cu复合粉末结构、形貌及相的影响。结果表明，随球磨时间的延长复合粉末发生细化达到纳米级粒度，球磨24h可获得稳定晶粒尺寸，最小晶粒尺寸为21．5nm。其中WC粉末晶粒细化速率较Cu的慢；球磨过程中，有少量的WC固溶于Cu中，形成Cu(WC)固溶体。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

正~~     

Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.