用非晶态合金作中间层扩散连接Si_3N_4与40Cr钢的研究

本文采用非晶态Ｃｕ_（５０）Ｔｉ_（５０）Ｂ薄膜和纯Ｎｉ缓释层作复合中间层，较好地实现了ｓｉ_３Ｎ_４与４０Ｃｒ钢的扩散连接，连接时间和连接温度及缓释层厚度对接头的强度影响很大最佳连接工艺为：９００℃·４０ｍｉｎ·３０ＭＰａ，Ｎｉ缓释层的合适厚度为１ｍｍ接头的微观分析表明：缓释层与非晶态Ｃｕ_（５０）Ｔｉ_（５０）Ｂ之间存在着较强的物理冶金交互作用，导致非晶态中间层中的Ｔｉ的活度降低，并产生脆性金属间化合物，使接头强度下限Ｍｏ是较理想的阻挡层材料在非晶态Ｃｕ_（５０）Ｔｉ_（５０）Ｂ与Ｎｉ缓释层之间插入Ｍｏ层，能有效地抑制两者间的物理冶金交互作用，并缓解了接头的残余热应力，提高了接头的强度本文提出了陶瓷与金属扩散连接接头的新模式为：陶瓷／用于扩散反应的中间层／阻挡层／缓释层／金属。     

用非晶态合金作中间层扩散连接Si3N4与40Cr钢的研究

本文采用非晶态Ｃｕ５０Ｔｉ５０Ｂ薄膜和纯Ｎｉ缓释层作复合中间层，较好地实现了Ｓｉ３Ｎ４与４０Ｃｒ钢的扩散连接，连接时间和连接温度及缓释层厚度对接头的强度影响很大，最佳连接工艺为：９００℃．４０ｍｉｎ．３０ＭＰａ，Ｎｉ缓释层的合适工为１ｍｍ，接头的微观分析表明，缓释层与非晶态Ｃｕ５０Ｔｉ５０Ｂ之间存在着较强的物理冶金交互作用，导致非晶态中间层的Ｔｉ的活度降低，并产生脆性金属间化合物，使接头强度下降，     

Si3N4／Ti／Ni／Ti／Si3N4部分瞬间液相连接接头的强度与断裂

在温度为１２７３－１４２３Ｋ,时间为０．９－７．２ｋｓ和０．１ＭＰａ压应力的条件下进行了Ｓｉ３Ｎ４／Ｔｉ／Ｎｉ／Ｔｉ／Ｓｉ３Ｎ４的部分瞬间液相连接,结合ＳＥＭ,ＥＤＳ和ＸＲＤ测试结果,分析了连接温度和时间对接头常温四点弯曲强度和断裂方式的影响。通过用反应层厚度来表征界面强度,用σ＾Ｒｅｓθｍａｘ来评价近界面陶瓷断裂,用σＲｅｓθ－０来评价界面断裂,建立了界面强度、陶瓷强度和残余应力与接头强度和三种     

Si_3N_4/Ti/Ni/Ti/Si_3N_4部分瞬间液相连接接头的强度与断裂

在温度为１２７３ ～１４２３ Ｋ、时间为０ ．９ ～７ ．２ ｋｓ 和０ ．１ ＭＰａ 压应力的条件下进行了Ｓｉ３Ｎ４／Ｔｉ／Ｎｉ／Ｔｉ／Ｓｉ３Ｎ４ 的部分瞬间液相连接, 结合ＳＥＭ, ＥＤＳ 和ＸＲＤ 测试结果, 分析了连接温度和时间对接头常温四点弯曲强度和断裂方式的影响。通过用反应层厚度来表征界面强度, 用σＲｅｓθｍａｘ 来评价近界面陶瓷断裂, 用σＲｅｓθ＝ ０ 来评价界面断裂, 建立了界面强度、陶瓷强度和残余应力与接头强度和三种断裂类型的关系模型。     

Cu—Nu—Ti合金钎料对Si3N4陶瓷的润湿与连接

采用座滴法研究了Ｃｕ－Ｎｉ－（２７－５６）Ｔｉ合金（原子分数,％,下同）在Ｓｉ３Ｎ４陶瓷上的润湿行为。选用真空熔炼合金Ｃｕ３８Ｎｉ３０Ｔｉ３２和Ｃｕ３４Ｎｉ２７Ｔｉ３９作为钎料时,获得的Ｓｉ３Ｎ４／Ｓｉ３Ｎ４接头的强度不理想。     

用非晶态合金作中间层对Si_3N_4陶瓷进行扩散焊连接

研制了两种非晶态物质Ｃｕ_（５０）Ｔｉ_（５０），Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作为对Ｓｉ_３Ｎ_４扩散焊连接的中间层材料．研究结果表明：用非晶态作为中间层可改善工艺条件，降低扩散焊温度；非晶态中间层接头比其相应晶态中间层接头的剪切强度有明显提高．其中硼对提高接头剪切强度贡献很大．用非晶态Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作中间层时，接头强度最高可达３４０ＭＰａ用晶态和非晶态Ｃｕ_（５０）Ｔｉ_（５０），Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作中间层对Ｓｉ_３Ｎ_４进行扩散焊连接的机制是：活性元素Ｔｉ向陶瓷界面扩散和富集并与Ｓｉ_３Ｎ_４发生反应生成界面相ＴｉＮ，ＴｉＳｉ_２等．从而实现连接．     

Cu-Ni-Ti合金钎料对Si_3N_4陶瓷的润湿与连接

采用座滴法研究了Ｃ４－Ｎｉ－（２７—５６）Ｔｉ合金（原子分数,％,下刚在Ｓｉ３Ｎ４陶瓷上的润湿行为选用真空熔炼合金Ｃｕ３８Ｎｉ３０Ｔｉ３２和Ｃｕ３４Ｎｉ２７Ｔｉ３９作为钎料时,获得的Ｓｉ３Ｎ／Ｓｉ３Ｎ４接头的强度不理想在降低钎料含Ｔｉ量的同时适当降低含Ｎｉ量,重新设计了两种Ｃｕ－Ｎｉ－Ｔｉ（Ｓｉ,Ｂ）合金钎料,并采用膏状形式改善针料成分的均匀性,在１３５３Ｋ,１０ｍｉｎ的针焊条件下获得的Ｓｉ３Ｎ４／Ｓｉ３Ｎ４接头最高三点弯曲强度分别提高至３３８．８和２０６９ＭＰａ,并对Ｓｉ３Ｎ４／Ｓｉ３Ｎ。接头的界面反应进行了分析     

CuNiTiB急冷钎料对Si3N4陶瓷的连接

经过急冷处理的Ｃｕ（５ ～２５）Ｎｉ（１６ ～２８） ＴｉＢ 钎料的组织比未经急冷处理的钎料更加均匀,有利于提高Ｓｉ３Ｎ４／Ｓｉ３Ｎ４ 接头的强度。当选用的钎料层厚度为４０ μｍ 和８０ μｍ 时, 接头的三点弯曲强度值分别达到４０２ ＭＰａ 和３８０ ＭＰａ 。分析了接头中元素Ｃｕ , Ｎｉ, Ｔｉ 的面分布。钎料层厚度大小影响接头的强度, 对其原因进行了探讨。     

用非晶态合金作中间层对Si3N4陶瓷进行扩散焊连接

研制了两种非晶态物质Ｃｕ５０Ｔｉ５０，Ｃｕ５０Ｔｉ５０Ｂ作为对Ｓｉ３Ｎ４扩散焊连接的中间层材料，研究结果表明，用非晶态作为中间层可改善工艺条件；降低扩散焊温度；非晶态中间层接头比其相应晶态中以接头的剪切强度有明显提高。其中硼对提高接头剪切强度贡献很大。用非晶态Ｃｕ５０Ｔｉ５０Ｂ作中间层时，接头强度最高可达３４０ＭＰａ。用晶态和非晶态Ｃｕ５０Ｔｉ５０，Ｃｕ５０Ｔｉ５０Ｂ作中间层对Ｓｉ３Ｎ４进行扩散焊     

Al／Ti／Al复合层原位生成金属间化合物连接陶瓷

用Al／Ti／Al复合层作连接材料，通过连接温度下原位生成金属间化合物真空连接Si3N4陶瓷。研究了Al与Ti的厚度匹配和工艺参数对接头显微组织及其强度的影响和接头的形成过程。结果表明：当原位生成的连接层金属组织为Al3Ti／Ti／Al3Ti时，由于纯金属间化合物Al3Ti脆性大，且其与剩余Ti片的结合强度低，陶瓷接头强度低；当连接层金属组织为大量Al3Ti颗粒加少量Al基固溶体时，连接层金属能获得良好的强化效果，与用纯Al连接的接头相比，接头室温和高温强度显著提高。Al与Ti的厚度匹配和连接参数适当时，接头室温和600℃剪切强度可分别达到89．4MPa和29．7MPa。     

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).     

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.     

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.     

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。