原位自生TiAl3增强Al基复合材料的组织结构及形成机理研究

采用冷喷涂技术沉积Ti-80Al（wt.%）复合涂层,通过热处理获得了原位自生TiAl3金属间化合物颗粒增强Al基复合材料涂层。采用SEM、EDS和XRD等分析了冷喷涂Ti/Al复合涂层在不同热处理温度下的组织结构演变规律及Ti、Al粒子间原位扩散反应过程,并对TiAl3金属间化合物的形成机理进行了探讨。结果表明,冷喷涂Ti/Al复合涂层组织致密,其相结构与喷涂粉末完全相同,450℃热处理后涂层局部区域发生Ti、Al间的固态扩散反应,并在Ti、Al粒子界面原位形成TiAl3金属间化合物,随着热处理温度升高,TiAl3金属间化合物的含量显著增加,600℃热处理后,Ti/Al复合涂层中的Ti粒子全部转变为TiAl3金属间化合物,获得原位自生TiAl3颗粒增强的Al基复合材料.     

反应合成Ti_3Al/TiC+Al_2O_3复合材料烧结过程热力学分析

将高能球磨后的Ti-Al粉末和TiC,Al2O3粉末混合进行热压烧结,在烧结的过程中反应生成金属间化合物为增强相的复合材料。通过对粉料的X射线衍射分析、热分析(DSC)和烧结体的成分分析表明,最终的金属间化合物只有Ti3Al而没有其它金属间化合物相。通过热力学计算,分析了反应烧结过程并发现在低温由固相间原子扩散控制生成TiAl3,TiAl,Ti3Al的渐进过程,和在高温下金属间化合物的合成机理,而且增强相和基体界面间处于稳定状态。     

反应合成Ti3Al/TiC＋Al2O3复合材料烧结过程热力学分析

将高能球磨后的Ti-Al粉末和TiC,Al2O3粉末混合进行热压烧结,在烧结的过程中反应生成金属间化合物为增强相的复合材料.通过对粉料的X射线衍射分析、热分析（DSC）和烧结体的成分分析表明,最终的金属间化合物只有Ti3Al而没有其它金属间化合物相.通过热力学计算,分析了反应烧结过程并发现在低温由固相间原子扩散控制生成TiAl3,TiAl,Ti3Al的渐进过程,和在高温下金属间化合物的合成机理,而且增强相和基体界面间处于稳定状态.     

不同工艺制备的TiAl金属间化合物微观组织特征

使用机械球磨制备细晶Ti/Al复合粉,采用不同的压制工艺,通过反应烧结和等温锻造方法获得不同晶粒尺寸的TiAl金属间化合物。对TiAl金属间化合物的微观组织特征进行了分析,研究了不同制备工艺对其微观组织的影响。结果表明:采用冷等静压630℃反应烧结及等温锻造工艺可以获得晶粒尺寸5～8μm的细晶TiAl金属间化合物;通过普通冷压、1250℃反应烧结与等温锻造后,也能获得近全致密的层片状TiAl金属间化合物,但晶粒尺寸为20～30μm。     

SiC／Ti基复合材料界面反应的热力学研究

通过建立热力学可能反应模型，分别计算了SCS－6 SiC长纤维增强Ti3Al和TiAl金属间化合物基复合材料界面反应的Gibbs函数变值△rG，并用△rG判据推测了界面反应产物并与透射电镜实验结果进行了对比分析。研究表明，由于TiAl中原子结合力较强，因而SCS－6 SiC/TiAl复合材料的界面反应较轻。所研究的2种复合材料界面反应的二元反应产物为TiC,Ti5Si3和Ti3Si,Ti-Si相图中的其它二元硅化物不可能形成。     

基于箔材反应退火合成的Ti Al基复合材料板材研究进展

本文综述了利用纯Ti箔和铝基复合材料(Al-MMC)箔反应退火合成Ti Al基复合材料板材的研究进展。该方法包括对多层Ti/Al-MMC复合板的变形和反应退火热处理,在避免对脆性TiAl金属间化合物直接变形的同时,制备出具有较高强度和延伸率的Ti Al基复合材料板材。对合成过程中Ti Al基复合材料板材的组织演化和形成机理进行了总结,重点阐明了铝基复合材料与Ti的两步热处理的反应机理,提出了消除Kirkendall孔洞的工艺方法,为大尺寸TiAl基复合材料板材的制备提供了可行的工艺方案。     

焊后热处理对钛/铝FSB接头组织及性能的影响

研究了6082铝合金和TC4钛合金分别添加钎料锌和镍下的搅拌摩擦钎焊(FSB)搭接接头微观组织及焊后热处理后接头界面金属间化合物(IMC)的生成种类和先后顺序以及生长动力学模型。研究表明:添加钎料锌时,界面金属间化合物主要由AlZn、TiAl、TiAl2、TiAl3组成,先后顺序为TiAl2→TiAl3→TiAl→AlZn,并获得了界面IMC层的生长动力学模型为;添加钎料镍时,界面金属间化合物层主要由TiNi、Al3Ni2、Ti3Al和TiAl组成,先后顺序为776 K以下,Ti-Ni-Al焊接界面金属间化合物形成的顺序是Al3Ni2→TiNi→TiAl→Ti3Al,776 K以上时生成顺序为Al3Ni2→TiNi→Ti3Al→TiAl,并获得了界面IMC层的生长动力学模型。界面IMC层的厚度均随着温度的提高或保温时间的延长而增加。添加锌的接头的剪切强度由未热处理时的154 MPa提高到194 MPa,而添加钎料镍的接头由142 MPa提高至166 MPa。     

SiC／TiAl界面固相反应研究

使用扫描电子显微镜、电子能谱仪、X射线衍射仪对经950～1100℃热处理的SiC/TiAl平面界面偶界面固相反应层的成分分布、微结构及相组成等进行了分析研究,讨论了SiC/TiAl界面固相反应机制,并对热处理过程中反应层成长的动力学过程进行了探讨,获得相应的动力学方程.结果表明,SiC/TiAl界面固相反应层主要由TiC、Ti5Si3Cx及Ti(Al,Si)2构成.其中,TiC和Ti5Si3Cx主要富集于邻近SiC的反应区,而Ti(Al,Si)2富集于邻近TiAl侧的反应区.SiC/TiAl界面固相反应的发生归因于TiC和Ti5Si3Cx数值大的负吉布斯自由能变化.SiC/TiAl界面固相反应层遵循抛物线生长规律,为扩散控制的反应过程,反应速率常数为:K=8.47×10-3exp(-322×103/RT)(m2/s).     

热压烧结制备钛基合金TiAl+Ti及其显微结构

在1473 K,30 MPa,1.5 h的热压条件下直接烧结TiAl金属间化合物和Ti混合粉末,制备了钛基合金(TiAl+Ti)样品,采用XRD、SEM研究了2种不同成分配比对烧结产物相组成及显微结构的影响。结果表明,不同成分配比热压烧结体的显微组织分布相差较大,但相组成基本相同;对于TiAl和Ti体积比7:3的钛基合金样品,Ti粉末中Fe元素易于固溶到Ti_2Al和Ti_3Al中,析出相主要由TiAl、Ti_2Al(Fe)、Ti_3Al(Fe)和富Ti相组成;该比例的混合粉末在热压烧结过程中发生了不同程度的扩散反应,最终形成了组织渐变的Ti/Ti_3Al(Fe)//Ti_2Al(Fe)/TiAl显微结构。     

Al2O3/TiAl复合材料的原位合成及反应机制的研究

利用Al-Ti-TiO2体系的放热反应,原位合成了Al2O3/TiAl复合材料.借助示差热分析法探讨了体系的反应机制,采用XRD、SEM和OM分析了复合材料的相组成及显微组织.结果表明,原位合成Al2O3/TiAl复合材料由TiAl、Ti3Al和Al2O3相组成,Al2O3颗粒分布于TiAl和Ti3Al双相交界处,并存在一定团聚.随其含量增加,团聚程度加剧,晶粒尺寸减小.Ti和Al反应生成TiAl3放出的热量使部分TiAl3相处于液相状态,熔融的体积分数约为87.87%,液相的存在提高了颗粒间的润湿性,同时放出的热量是引发后续反应的原因之一.TiAl3与Al-TiO2的还原反应生成的活性Ti原子结合最终生成了TiAl和Ti3Al相.     

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

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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.