Yanqing SU
,
Tiejun ZHANG
,
Jingjie GUO
,
Hongsheng DING
,
Weisheng BI
,
Jun JIA
,
Hengzhi FU
材料科学技术（英文）
Mold-filling process of thin-walled castings under the condition of traveling magnetic field has been studied by physical simulation method using gallium melt and fast speed photography. Flow morphology and its formation mechanism were obtained and discussed for thin-walled casting. The influences of magnetic field density on the filling ability, filling velocity and mold filling time have been studied. The differences in filling capability between gravity casting and casting under the traveling magnetic field have been compared. The results indicate that the mold filling ability of the gallium melt increases greatly under the condition of traveling magnetic field; the filling time is shortened from 18 s under gravity field to 3 s under the traveling magnetic field and average flow rate of the melt increases from 1.6 to 8.68 cm3/s; the change law of the cross-section morphology of the gallium melt during the mold filling is that at first, the cross-section area does not change, then it decreases gradually. When the front of the melt reaches the end of the mold cavity, the front melt will backfill the mold; the wider the width of mold cavity, the better the mold filling ability. The mold filling ability of gallium melt in mold with upper magnetic conductor is better than that without upper magnetic conductor.
关键词:
Traveling magnetic field
,
null
,
null
,
null
Hongwen He
材料科学技术（英文）
Bi layer formation in Cu/Sn{58Bi/Cu solder joints was investigated with different current densities and solder thickness. Uniform and continuous Bi layers were formed at the anode interface which indicated that Bi was the main diffusing species migrating from the cathode to the anode. The electromigration force and Joule heating took on the main driving forces for Bi diffusion and migration. In addition, two appearance types of Bi layers, planar-type and groove-type, were found during current stressing. The morphology and thickness of Bi layers were affected by current density and current stressing time.
关键词:
Bi layer formation
,
null
,
null
,
null
康智强
,
杨雪
,
冯国会
,
张林
材料研究学报
doi:10.11901/1005.3093.2016.227
结合数值模拟与实验研究了常规条件下Al-Bi偏晶合金难混溶区的凝固过程,分析了Bi含量对Al-Bi偏晶合金显微组织演变的影响.结果表明,成分为Al-10％Bi合金试样下部组织中富Bi液滴的平均直径和体积分数分别是成分为Al-5％Bi合金试样下部组织中富Bi液滴平均直径和体积分数的1.1倍和12.8倍,且Al-10％Bi合金试样下部聚集了大量的大尺寸富Bi液滴,其显微组织均匀性较差;成分为Al-5％Bi的合金试样中富Bi液滴的平均尺寸较小,显微组织较均匀;偏晶点成分的Al-3.4％Bi偏晶合金显微组织中无大尺寸富Bi液滴生成,显微组织均匀.分析表明,富Bi相含量的增加导致液滴受重力作用增强,加剧了难混溶区液-液相分离和分解的凝固行为,增大了富Bi液滴的尺寸和数量,液滴受到的Ostwald熟化和碰撞凝并的作用增强,促使大量的大尺寸富Bi液滴聚集在试样下部,加重了偏晶合金显微组织的宏观偏析.
关键词:
金属材料
,
Al-Bi偏晶合金
,
合金成分
,
显微组织
,
重力迁移
何砚发
,
吕朝阳
,
王金星
低温物理学报
doi:10.3969/j.issn.1000-3258.2003.z1.014
本文介绍一种能够迅速获得Bi系带材多种性能参数的方法.它采用计算机进行数据采集和控制,在不断改变外力和外场的同时,对样品施加缓慢变化的传输电流,从而连续测出样品在不同应变和外场下的临界电流.该方法可以方便地获得Bi系带材的应力-应变曲线,临界电流-应变曲线,外场-临界电流曲线,不同应变下的伏安特性曲线以及不同外场下的伏安特性曲线等.通过对几种带材性能的研究表明,该方法简单实用,数据可靠,可供广大材料研究者和材料应用研究人员使用.
关键词:
邹元爔
金属学报
<正> 鉛的去鉍可以用沉淀精炼的方法,用Ca,Mg,K等金属为沉淀剂,生成的金属間化合物有Mg_3Bi_2(s),Ca_3Bi_2(s),CaMg_2Bi_2(s)及K_9Mg_6Bi_7(s)等。本文目的是利用已有数据計算这些金属間化合物的标准生成自由能,以期对沉淀去鉍过程获得进一步的了解。 从Mg-Bi相图可見,在液相綫上Mg_3Bi_2(s)与熔液成平衡。因此,可以从Mg-Bi系的活度数据結合相图计算Mg_3Bi_2(s)的标准生成自由能,同样方法曾被用来計算InSb(s)的标准生成自由能。液相綫上的平衡可以用下式表示:
关键词:
FENG Shuifu ZHO U Jicheng Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai
,
China ZHOU Jicheng
,
Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai 200050
,
China
金属学报(英文版)
A modified liquid phase epitaxy apparatus for semiconductor materials was used to measure the solubility of GaAs in Bi.Two phase diagrams rich in Bi under H_2 and N_2 atmospheres were obtained according to the results of measurement.A new phenomenon,in which the parameter Q value(quantity of GaAs dissolved in Bi in fixed time/saturation quantitu,of GaAs in Bi)was different from each other at various temperatures and there existed a maxi- mum Q value at definite temperature,was observed.This phenomenon may be regarded as a common feature of a simple binary metallic system which has the phase diagram similar to that of Bi-GaAs.The difference observed from the dependence of Q values on temperature in both H_2 and N_2 atmospheres was discussed.
关键词:
solubility
,
null
,
null
Journal of Electronic Materials
In this study, the influences of substrate alloying and reflow temperature on the Bi segregation behaviors at the Sn-Bi/Cu interface were investigated. Cu and Cu-Ag alloys with different Ag contents were reflowed with Sn-Bi solder at 180A degrees C, 200A degrees C or 220A degrees C, and then aged at 120A degrees C for different times. The evolution of their interfacial morphologies during the aging process was observed, and tensile tests of some solder joints were conducted. The experimental results reveal that the Bi atoms that dissolved in the Cu(6)Sn(5) during the reflow process are expelled when the Cu(6)Sn(5) transforms into Cu(3)Sn and then segregate around the Cu(3)Sn/Cu interface, inducing interfacial embrittlement. Alloying the Cu substrate with Ag can alleviate the Bi segregation by suppressing Cu(3)Sn formation and dissolving the Bi atoms in the Cu-Ag substrate; the critical Ag content to eliminate the Bi segregation is about 1 at.% for the interface reflowed at 200A degrees C. For interfaces reflowed at 180A degrees C, the Bi segregation is less serious because less Bi is dissolved in the Cu(6)Sn(5), and 0.6 at.% Ag can eliminate it. Tensile tests demonstrate that the embrittlement will not occur at Sn-Bi/Cu-Ag joints once the Bi segregation is eliminated. Based on this understanding, aging embrittlement of Sn-Bi/Cu solder joints can be prevented by decreasing the reflow temperature and adding a small amount of Ag to the Cu substrate.
关键词:
Sn-Bi solder;Bi segregation;interfacial embrittlement;substrate;alloying;reflow temperature;tensile strength;lead-free solders;joints;microstructure;embrittlement;interconnect;bismuth;ag
Acta Physica Sinica
Sn-Bi nanometer powders were produced by an electrohydrodynamic technique. The microstructural feature of Sn-Bi nanometer powders was investigated by means of XRD, TEM and HREM. The results show that Sn-Bi nanometer powders produced are composed of tetragonal beta-Sn monophase supersaturated solid solution and rhombohedral Bi monophase supersaturated solid solution. Most of the Sn-Bi nanometer powders are single crystals, only a few Sn-Bi nanometer powders are twin crystals. The particles of < 10 nm in diameter are perfect single crystals. There exist dislocations in the particles larger than 10 nm in diameter. The formation mechanism of microstructure for Sn-Bi nanometer powders is analyzed.
关键词:
nanocrystalline materials;mossbauer-spectroscopy;alloys
