Ti2AlNb合金瞬时液相扩散连接接头界面组织及性能分析

采用Ti/Ni作为中间层实现了Ti2AlNb合金的连接(transient liquid phase, TLP)，研究了TLP连接接头的界面组织及其形成机制，并且分析了不同保温时间对接头界面组织和力学性能的影响规律. 结果表明,Ti2AlNb合金TLP连接接头主要表现为等温凝固区和冷却凝固区两个明显的特征区域. 接头的典型界面组织为Ti2AlNb/B2/Nb3Al+B2+τ3+Ti2Ni/ Ti2AlNb. 随着保温时间的延长，接头中Nb3Al和Ti2Ni相消失，τ3相不断减少，B2相不断增多. 当连接温度为1 180 ℃，保温时间为20 min时，接头的室温抗剪强度最大，达到428 MPa，高温(650 ℃)抗剪强度达到407 MPa. 接头的断裂主要发生在冷却凝固区的τ3相上.     

TiAl/Ni基合金反应钎焊接头的微观组织及剪切强度(英文)

以Ti为中间层,对TiAl基金属间化合物与Ni基高温合金进行反应钎焊连接,研究反应钎焊接头的界面微观结构及剪切强度。通过实验发现,熔融中间层与两侧母材反应剧烈,生成连续的界面反应层。典型的界面微观结构为GH99/(Ni,Cr)ss(γ)/TiNi(β2)+TiNi2Al(τ4)+Ti2Ni(δ)/δ+Ti3Al(α2)+Al3NiTi2(τ3)/α2+τ3/TiAl。当钎焊温度为1000°C,保温时间10min时,所得接头的剪切强度最高为258MPa。进一步升高钎焊温度或延长保温时间,会引起钎缝组织中组成相粗化和脆性金属间化合物层的生成,从而导致接头剪切强度的降低。     

5005铝合金与4J34可伐合金的真空钎焊工艺

利用Al-Si-Mg钎料实现5005铝合金与4J34可伐合金的真空钎焊,研究了接头界面结构及其形成机理,分析了钎焊温度及保温时间对接头界面结构和抗剪强度的影响。结果表明:随着钎焊温度的升高和保温时间的延长,接头的抗剪强度先升高后降低;当钎焊温度为580℃、保温时间为15 min时,接头抗剪强度达到最大值81 MPa,此时,接头的典型界面结构为4J34可伐合金/FeAl/FeAl3/FemAln+α(Al)/5005铝合金。接头的断裂形式主要受钎焊温度的影响;当钎焊温度较低时,接头断裂于铝合金侧氧化膜层及铝合金内;当温度升高至580℃时,接头断裂于FemAln+α(Al)反应层中。     

TiAl基合金与Ni基合金钎焊连接接头界面组织及性能

采用BNi2钎料实现了TiAl基合金与Ni基高温合金的钎焊。采用扫描电镜、能谱分析和X射线衍射等手段对钎焊接头的界面组织结构及生成相进行分析,并对接头的抗剪强度进行测试。结果表明,钎焊接头的典型界面结构为：GH99/(Ni)ss (γ)+Ni3B+CrB+富Ti-硼化物/TiNi2Al/TiNiAl+Ti3Al/TiAl;随着钎焊温度的升高或保温时间的延长,较多的B和Si元素扩散进入两侧母材,导致钎缝中硼化物数量减少,而TiAl/钎缝界面的TiNi2Al和TiNiAl+Ti3Al金属间化合物层厚度增加;当钎焊温度为1050 ℃,保温时间为5 min时,接头的抗剪强度达到最大为205 MPa,接头主要断裂于TiNiAl金属间化合物层。当钎焊温度升高或保温时间继续延长时,TiNiAl厚度显著增加,导致接头强度下降     

母材微量元素对6063铝合金接触反应钎焊的影响

采用铜中间层对6063铝合金进行了接触反应钎焊连接,分析了接头的典型界面结构,着重研究了铝合金母材中微量元素对界面及接头力学性能的影响行为.结果表明,接头界面相主要有Al2Cu,α-Al,Mg2Si,ω-FeCu2Al7.Fe元素导致较高连接温度下ω-FeCu2Al7板条相的生成,影响接头强度.Mg,Si元素以Mg2Si形式富集在钎缝中心,并随保温时间的延长而加剧富集.接头抗剪强度受控于界面产物的种类及形貌、等温凝固的程度.在570℃/60min时接头平均抗剪切强度最高,可达105.3MPa.     

5005铝合金与1Cr18Ni9Ti的真空钎焊分析

采用Al-Si-Mg钎料成功实现了5005铝合金与1Cr18Ni9Ti不锈钢的真空钎焊,借助扫描电镜、能谱分析仪和X射线衍射仪对焊后接头界面组织进行分析,同时对接头抗剪强度进行测试.结果表明,焊后接头界面结构从1Cr18Ni9Ti不锈钢侧到5005铝合金侧的界面组织依次为FeAl,FeAl₃,Fe_mAl_n+αAl.随着钎焊温度的升高或保温时间的延长,接头抗剪强度均呈现先升高后降低的变化趋势.当钎焊温度为580℃,保温时间为15 min时,接头抗剪强度达到最大值49 MPa.接头断裂形式受钎焊温度的影响,当钎焊温度较低时,接头断裂于铝合金侧氧化膜层及Fe_mAl_n+αAl反应层;温度升高至580℃时,接头断裂于Fe_mAl_n+αAl反应层中,接头抗剪强度最高.     

Ti3Al与316L不锈钢的真空钎焊工艺

采用Ag-Cu钎料对Ti_3Al与316L不锈钢进行真空钎焊连接,通过扫描电镜、能谱分析仪和X射线衍射仪分析了接头界面结构并对其形成机理进行了分析,同时,研究了钎焊温度对接头界面组织以及抗剪强度的影响。结果表明,在固定保温时间为5 min时,接头的抗剪强度先随着钎焊温度的升高而增大,当钎焊温度为800℃时,接头抗剪强度达到最大值为343 MPa,当钎焊温度进一步升高时,接头抗剪强度会呈现降低趋势。接头的典型界面结构为Ti_3Al/Al Cu_2Ti+Cu_2Ti+Cu(s,s)+Ag(s,s)+Cu Ti+Fe_2Ti/316L不锈钢。     

SiO2玻璃陶瓷与TC4钛合金的活性钎焊

分别采用活性钎料AgCuTi和TiZrNiCu对SiO2陶瓷和TC4钛合金进行了钎焊连接,使用扫描电镜和X射线衍射等手段对接头的界面组织和力学性能进行了研究.结果表明,采用两种钎料均能够实现对SiO2陶瓷和TC4钛合金的连接;SiO2/TiZrNiCu/TC4接头的典型界面为SiO2/Ti2O+Zr3Si2+Ti5Si3/(Ti,Zr)+Ti2O+TiZrNiCu/Ti基固溶体/TiZr-NiCu+Ti基固溶体+Ti2(Cu,Ni)/TC4;SiO2,AgCuTi/TC4接头的典型界面为SiO2/TiSi2+Ti4O7/TiCu+Cu2Ti4 O/Ag基固溶体+Cu基固溶体/TiCu/Ti2Cu/Ti+Ti2 Cu/TC4.当钎焊温度为880℃和保温时间为5 min时,SiO2/TiZrNiCu/TC4接头的最高抗剪强度为23 MPa;当钎焊温度为900℃和保温时间为5 min时,SiO2/AgCuTi/TC4接头的最高抗剪强度为27MPa.     

ZrB_2-SiC陶瓷复合材料钎焊接头界面组织及性能

采用BNi2钎料,对ZrB2-SiC陶瓷复合材料进行真空钎焊研究.借助SEM,EDS,XRD等分析测试手段分析了界面组织结构及性能.确定了最佳钎焊工艺参数:钎焊温度1160℃,保温时间20 min.结果表明,接头界面产物主要有δ-Ni2Si,β1-Ni3Si,ZrB2+C,Ni(s,s),Cr x B y C z.随着钎焊温度升高以及保温时间的延长,接头抗剪强度均先升高后降低.钎焊温度1 160℃,保温时间20 min,钎焊接头室温抗剪强度达到最大121.3 MPa.钎焊温度和保温时间对接头断裂方式的影响有相似的规律,在保温时间较短时,裂纹主要产生于钎缝中的Ni(s,s)中,之后向Ni元素扩散层中扩展;当保温时间适中时,断裂主要发生在Ni元素扩散层中;当保温时间延长时,裂纹主要产生于含有一定β1-Ni3Si相的Ni(s,s)中,之后向Ni元素扩散层中扩展.     

7A52铝合金封接Al2O3陶瓷工艺

采用钎焊对7A52铝合金和直径φ10 mm表面镀镍的氧化铝陶瓷球进行封装,研究了加热温度和保温时间对显微组织特征、特征点成分和抗剪强度的影响。结果表明,采用硅镁焊料的7A52铝合金和Al2O3(Ni)陶瓷封接的最佳工艺参数：加热温度为590 ℃,压力2 MPa,保温时间1 h,反应层厚度在10～27 μm,接头达到的最大抗剪强度为24.8 MPa,接头界面结构为Al2O3陶瓷/Al-Ni金属间化合物/Al-Si共晶/7A52铝合金。     

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。