Cu/Sn-58Bi/Cu焊点在电迁移过程中晶须和小丘的生长

利用SEM和EDS研究了Cu/Sn--58Bi/Cu焊点在电流密度为5×10³ A/cm², 80℃条件下晶须和小丘的生长. 通电540 h后, 在焊点阴极界面区出现了钎料损耗, 同时形成了晶须, 而在阳极Cu基板的钎料薄膜上形成了大量弯曲状晶须和块状小丘. EDS检测表明, 这些 晶须和小丘为Sn和Bi的混合物. 通电630 h后, 阳极上的晶须和小丘数量明显增多, 原来形成晶须的尺寸和形状没有变化, 阴极界面处 形成Cu₆Sn₅金属间化合物. 上述现象表明: 电迁移引发了金属原子的扩散迁移, 从而在阳极Cu基板上形成了一层钎料薄膜. 钎料薄膜中金属间化合物的形成导致压应力的产生, 促使晶须和小丘生长, 而阴极钎料损耗区域内晶须的形成与Joule热聚集有关.     

高温时效过程中SnAgCu钎焊接头显微组织的演化规律

研究了215℃时效过程中Sn3.8Ag0.7Cu无铅钎料焊点内部及与Cu基板界面处显微组织的演化规律.结果表明:试样在时效过程中的放置方式对显微组织的变化会产生重要影响.当钎料焊点处于Cu基板的上方时,215℃时效后显微组织的变化与以往170℃时效后显微组织的变化相似,即界面处金属间化合物层的厚度会随着时效时间的延长而逐渐增加.然而,当钎料焊点处于Cu基板的下方时,215℃时效后钎料焊点内部及界面处的显微组织发生了显著的变化,伴随着Cu基板的溶解在钎料焊点表面形成了大量的体积较大的金属间化合物Cu6Sn5.     

不同钎剂对Sn-Zn系无铅钎料润湿特性的影响

采用润湿平衡法研究了在znC12一NH4C1、中等活性松香(RMA)和免清洗三种不同钎剂作用下,Sn-Zn无铅钎料在Cu基板上的润湿特点.结果表明,使用ZnC12-NH4C1钎剂时,Sn-Zn钎料具有良好的润湿性能;研究了不同钎剂下,Sn-9Zn钎料在Cu基板上的铺展情况,并分析比较了焊点界面金属间化合物层的特征.Sn-Zn钎料与Cu基板界面形成的金属间化合物在靠近Cu基板一侧较为平坦,而在钎料一侧呈扇贝状,而且,不同钎剂能影响钎料在Cu基板上的润湿、铺展性能,界面金属间化合物特征及焊点外观;Sn-Zn钎料表面存在大量ZnO,去除钎料表面ZnO是开发针对Sn-Zn系无铅钎料专用钎剂的关键.     

电流作用下Cu/Sn-15Bi/Cu焊点的组织演变

对Cu/Sn-15Bi/Cu焊点在150℃下的电迁移组织演变进行了研究. 结果表明,焊点阳极侧出现了近共晶相的偏聚,近共晶相厚度随电迁移时间的延长而逐渐增加;受“电子风”力的影响,钎料中Cu6Sn5金属间化合物逐渐向阳极侧偏聚,此外,由于阴极侧Cu6Sn5界面金属间化合物的脱落,钎料中的Cu6Sn5金属间化合物体积分数逐渐增加;焊点阴极侧界面金属间化合物厚度随电迁移时间延长逐渐增加,阳极侧界面金属间化合物厚度随电迁移时间延长先增加,后降低,当电迁移时间超过5 h后,界面金属间化合物厚度迅速增加.     

Cu/Sn3.0Ag0.5Cu/Cu焊点电迁移过程中界面应力演变的研究

应用X射线衍射技术原位测量分析了Cu/Sn3.0Ag0.5Cu/Cu焊点在电流密度为4×103A/cm2的作用下阴极和阳极界面的应力演变。结果表明:焊点阴极和阳极界面的应力演变非常复杂,大致分为4个阶段。第一个阶段,由于金属热膨胀效应促使焊点界面的压应力开始升高;第二个阶段,应力松弛的影响使得压应力开始降低;第三个阶段,电迁移的作用使得阳极界面压应力增加而阴极界面由压应力向拉应力转变;第四个阶段,阳极处晶须和小丘的形成释放了压应力,阴极处的拉应力继续增加。试样抛光后发现,在焊点阳极界面形成了一层厚度均匀的Cu6Sn5金属间化合物。     

Ni添加量对铜基板和石墨烯铜基板的界面反应和IMC生长的影响（英文）

研究了钎焊与时效过程中,在Sn0.7Ag0.5Cu(SAC0705)钎料与Cu基板和石墨烯Cu基板界面处金属间化合物(IMC)的形成与演变。采用加热平台制备焊接试样并在120℃时效600h。结果表明,界面金属间化合物在时效过程中增厚。SAC0705/Cu和SAC0705/G-Cu 2种焊接界面金属间化合物均为Cu6Sn5。当钎料中添加Ni元素后,Cu6Sn5化合物转变为(Cu, Ni)6Sn5。随着钎料中Ni元素含量的增大,2种基板上的界面金属间化合物厚度先增加后减小。此外,随着Ni含量增大,化合物生长速率降低。石墨烯Cu基板表面的石墨烯层起到扩散阻挡层效果,因此,石墨烯Cu板上的化合物厚度小于常规Cu基板,同时其界面化合物生长速率较低。     

RE对Sn2.5Ag0.7Cu/Cu焊点性能的影响

利用X射线衍射分析仪(XRD)和JSM-5610LV扫描电镜(SEM)研究RE含量对Sn2.5Ag0.7Cu/Cu焊点界面区显微组织、剪切强度和蠕变断裂寿命的影响。结果表明:Sn2.5Ag0.7CuxRE焊点界面区金属间化合物由靠近钎料侧Cu6Sn5和靠近Cu基板侧Cu3Sn构成;添加微量RE可细化Sn2.5Ag0.7Cu焊点内钎料合金的显微组织和改善钎焊接头界面区金属间化合物的几何尺寸及形态;当RE添加量为0.1%时,焊点的剪切强度最高,蠕变断裂寿命最长。     

电迁移引发Cu/SnBi/Cu焊点组织形貌的演变

主要研究电流密度为5×103 A/cm2,室温和高温(100 ℃)条件下共晶SnBi焊点的电迁移特性.结果表明:室温条件通电465 h后,阳极界面处出现Bi的挤出,阴极界面处出现裂纹;而在高温条件下通电115 h后,组织形貌发生了很大的变化.高温加速了阴极钎料的损耗,导致电流密度在局部区域高度集中,从而产生更多的焦耳热,最终引发焊点的熔化.熔融状态下Sn原子与Cu反应,在基体形成大量块状的Cu6Sn5金属间化合物,严重降低焊点的可靠性.     

Ti90及其优化合金的组织与力学性能研究

研究了钎焊与时效过程中,在Sn0.7Ag0.5Cu(SAC0705)钎料与Cu基板和石墨烯Cu基板界面处金属间化合物(IMC)的形成与演变。采用加热平台制备焊接试样并在120℃时效600h。结果表明,界面金属间化合物在时效过程中增厚。SAC0705/Cu和SAC0705/G-Cu 2种焊接界面金属间化合物均为Cu6Sn5。当钎料中添加Ni元素后,Cu6Sn5化合物转变为(Cu,Ni)6Sn5。随着钎料中Ni元素含量的增大,2种基板上的界面金属间化合物厚度先增加后减小。此外,随着Ni含量增大,化合物生长速率降低。石墨烯Cu基板表面的石墨烯层起到扩散阻挡层效果,因此,石墨烯Cu板上的化合物厚度小于常规Cu基板,同时其界面化合物生长速率较低。     

Sn-6.5Zn钎料/Cu基板焊点界面特征与金属间化合物的形成机理

对255℃时Sn-6.5Zn钎料/Cu基板界面反应及金属间化合物的形成与转化进行热力学计算与分析,并利用SEM、EDS、XRD研究分析255℃不同钎焊时间条件下钎料/Cu基板界面组织与IMC层形态特征。结果表明:Sn-6.5Zn钎料/Cu焊点界面紧靠Cu基板侧形成CuZn层;CuZn IMC有与钎料中的Zn原子继续反应生成Cu5Zn8 IMC的趋势;在相同钎焊温度条件下,不同钎焊时间对界面厚度影响不大;随钎焊时间延长,Sn-6.5Zn钎料/Cu基板焊点界面IMC层的平均厚度增大,界面粗糙度则由于不同钎焊时间IMC在液态钎料中生长与溶解的差异,呈现先增大而后降低到一个均衡值的变化趋势。     

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.