Ag-Cu合金包套掺铪超导Bi-2223带材Jc达9.5 ×10~4/cm~2

Ｂｉ－２２２３超导带已成为高Ｔｃ氧化物超导材料最有希望的选材,因其容易通过粉末套管工艺制备,７７Ｋ和０Ｔ下的临界电流密度Ｊｃ可高达６．９ × １０４／ｃｍ２;通过采用Ａｇ－Ｃｕ合金包套又可以在保持高Ｊｃ性能下增加机械强度;如果再在Ａｇ－Ｃｕ合金包套中杂Ｔｉ,改进,４．２Ｋ下Ｊｃ提高两倍多．这种带材制作的磁体系统可以直接靠小型制冷机冷却在２０Ｋ运行,开辟了高Ｔｃ氧化物超导带的新应用,现已被用于制造磁分离装置． 为了满足这些新应用项目的需求,有必要全面研究掺杂合金包套Ｂｉ－２２２３带材Ｊｃ与温度和磁场…     

Bi—2223超导带的拉伸特性和芯丝断裂可能性

带状Ｂｉ－２２２３超导体有众多的用途,但条件是必须兼具高的临界电流密度和足够的强度．为此,日本东京大学和国立金属所等单位的研究者,采用类似弓形样品某装置,研究了Ｂｉ－２２２３超导带的机械性能． 实验是在粉末套管法制备的６１芯包银带上进行的,最终成形带子尺寸宽为３．４ｍｍ、厚０、２４ｍｍ,处理后带子的临界温度为１０８Ｋ．自场７７Ｋ下传输Ｊｃ为１８．５ｋＡ／ｃｍ２,应变试验样品长度７ｃｍ,在大口径磁体和不同温度（４．２Ｋ． ２０Ｋ和７７Ｋ）下试验．先用一般锡焊将Ｂｉ－２２２３超导带固定在Ｕ形黄铜弹簧架…     

银包覆Bi2223超导带材的热压试验研究

对银包覆Ｂｉ２２２３高温超导带材的热压作了系统试验研究，确定了合理的带材热压处理工艺规范。结果表明热压处理能提高超导带中粉芯的密度和晶粒织构度，从而提高超导带材临界电流密度Ｊｃ。超导带材的Ｊｃ与热压的温度、压力、热压与冷压的结合方式等有密切的关系。最大的Ｊｃ为２．２×１０４Ａ／ｃｍ２，７７Ｋ，０Ｔ。     

磁场、温度对Bi-2223/Ag多芯带Jc的影响

介绍了一套液氮温区入（Ｂ,Ｔ）测量系统,该系统用增大液氮的饱和蒸气压来达到提高液氮温度的目的。用该系统研究了磁场和温度（测量范围分别为０．１Ｔ～０．８Ｔ和７７Ｋ～９０Ｋ）对Ｂｉ－２２２３／Ａｇ多芯带材（１９芯和３７芯）临界电流的影响。     

W＆RBi－2223饼状磁体实验研究

研究了Ｗ＆Ｒ（先绕后烧）工艺中弯曲半径、绝缘材料对银套Ｂｉ－２２２３带材Ｉｃ的影响。用Ｗ＆Ｒ法制备了内径１６ｍｍ、外径８０ｍｍ．高４７ｍｍ四双饼串联组合磁体，４．２Ｋ下Ｉｃ＝５５Ａ．磁体中心磁场Ｂ０＝０．４４Ｔ。     

冷等静压与热压结合制造Bi-2223电流引线

由于高温超导氧化物在低于Ｔｃ的温度下热导低,因此,高温超导电流引线引起了人们的广泛注意．Ｖ．Ｐｌｅｃｈａｃｅｋ和Ｊ．Ｈｅｊｔａｍａｎｅｋ曾报道过冷等静压（ＣＩＰ）制造的Ｂｉ－２２２３管状电流引线,其临界电流密度（Ｊｃ）在７７Ｋ下为１０００Ａ／ｃｍ２．澳大利亚学者Ｖ． Ｒｏｕｅｓｓａｃ等人采用单轴压制的方法制造了织构良好的Ｂｉ－２２２３圆片,其Ｊｃ为１０ ０００Ａ／ｃｍ２．到目前为止,管状电流引线在７７Ｋ和自场中的最高Ｊｃ超过了１０００Ａ／ｃｍ２,而采用ＣＩＰ法制造的棒状电流引线在７７Ｋ和自场中的Ｊ…     

W＆R Bi—2223饼状磁体实验研究

研究了Ｗ＆Ｒ工艺中弯曲半径，绝缘材料对银套Ｂｉ－２２２３带材ＩＣ的影响，用Ｗ＆Ｒ法制备了内径１６ｍｍ，外径８０ｍｍ、高４７ｍｍ四双饼串联组合磁体，４．２Ｋ下ＩＣ＝５５Ａ，磁体中心磁场Ｂ０＝０．４４Ｔ。     

单芯Bi（2223）带制备工艺参数的最佳化和轧制压力对J_c的影响

单芯Ｂｉ（２２２３）带制备工艺参数的最佳化和轧制压力对Ｊ_ｃ的影响最近，采用轧制方法制备的长带传输性能又有令人鼓舞的结果，这种长带的临界电流密度接近单轴压制带的性能，其Ｊｃ（７７Ｋ，０Ｔ）≥３０ｈＡ·ｃｍ（－２）。因此，现在已成功地制造了７７Ｋ下超过...     

层状Bi—2212／Ag多芯带的制造

人们普遍认为，Ｂｉ－２２１２超导线和带是高场（＞２０Ｔ）应用最优良的候选材料．导体由多芯组成也很重要，因为多芯可以沿整个长度均分性能的变化．多芯导体还可通过较大的断面缩减使氧化物芯密实，从而增强沿银－氧化物界面的晶粒排列．上述因素是采用Ａｇ／Ｂｉ－２２１２材料获得高场磁体的关键． 在Ｂｉ－２２２３多芯带的研究中，观察到与银层相邻的Ｂｉ－２２２３晶粒是高临界电流密度区．最近的研究又表明，Ｂｉ－２２１２带中光滑的银－氧化物界面对于获得所需要的Ｊｃ值是很重要的，因为光滑的银－氧化物界面会产生均匀的和高…     

加银Bi系高温超导带材的抗弯性能测试

对加银和不加银Ｂｉ－２２２３／Ａｇ带材的弯曲应变特性进行了研究，并对两种带材进行了ＸＲＤ和ＳＥＭ分析。试验证明，加银粉带材的机械性能高于不加银带材，制造线圈后，Ｊｃ也较高。     

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.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。