变压器Cu/Al端子超声波液相钎焊界面组织结构

Cu/Al超声波液相钎焊接头界面区主要由钎缝、Al基体和Cu基体组成,钎缝区组织主要由β-Sn相和针状富Zn相组成,基体与钎缝附近存在大量针状富Zn相分别从Cu母材和Al母材一侧向钎缝中生长的现象.钎缝组织硬度与Al基体侧较为接近,未发现钎缝存在显著的高硬度区.钎焊接头Cu侧主要由Cuo.64 Zn0.36相组成,未发现存在Cu-Sn系金属间化合物.     

药芯铝钎料钎焊Cu/Al异种金属接头的力学性能及反应物

以3种药芯铝钎料对Cu/Al异种金属进行了火焰钎焊,研究了钎焊接头的力学性能及反应物.通过测试和分析3种钎焊接头的强度、组织和显微硬度,从中选取综合性能较优的试样ZAAg2;采用扫描电镜(SEM)、X射线衍射仪(XRD)、X射线能谱仪(EDS)等进一步分析该钎焊接头的组织及反应物.结果表明:性能较优钎焊接头ZAAg2接头强度高达75 MPa,接头的主要断裂形式为沿晶脆性断裂,断裂主要产生在CuAl,CuAl2,Al4Cu9等脆性组织与α - Al基体的界面处.钎料与母材发生界面反应,钎缝中靠近铝侧生成α-Al固溶体,靠近铜侧生产CuAl,CuAl2,Al4 Cu9等脆性相.     

Cu/Al异种金属钎焊接头的组织与性能研究

使用三种Zn-Al系钎料对Cu/Al异种金属进行感应钎焊试验,研究了Cu/Al异种金属焊接接头的显微组织、力学性能和耐腐蚀性能。结果表明,相对于Zn-2Al和Zn-2Al-1Ag钎缝,Zn-13Al-5Ag钎缝组织有更多的弥散分布的Al2Cu相;Zn-13Al-5Ag钎焊接头的显微硬度和腐蚀前后的剪切强度最大,Zn-2Al和Zn-2Al-1Ag钎缝的显微硬度相当;Cu母材耐腐蚀性能最好,Al母材耐腐蚀性能最差,而这三种钎缝的耐腐蚀性能从高至低依次为Zn-13Al-5Ag钎缝Zn-2Al-1Ag钎缝Zn-2Al钎缝,其耐腐蚀性能均高于Al母材。     

Zn-Al钎料钎焊Cu/Al接头组织和性能(英文)

使用不同成分的Zn-Al钎料对铜铝异种金属进行火焰钎焊,研究其力学性能。利用光学显微镜、扫描电镜和能谱研究不同Zn-Al钎料对Cu/Al钎焊接头钎焊性、力学性能及显微组织的影响。结果表明:随着Al含量的增加,Zn-Al钎料在Cu和Al上的铺展面积逐渐增大。当钎料中Al含量为15%时,Cu/Al接头的抗剪强度达到最大值88MPa;随着组织的变化,钎缝硬度值呈现HV122到HV515不等的分布。另外,钎缝组织的成分主要为富Zn相和富Al相,但是当钎料中Al含量为2%和15%以上时,靠近Cu侧的界面处会分别形成CuZn3和Al2Cu两种完全不同的金属间化合物。研究Zn-Al钎料中铝含量对Cu/Al接头界面化合物类型的影响。     

Al-Si-Cu-Zn急冷钎料钎焊铝及铝合金的界面结构及强度

采用Al70Si7.5Cu20Zn2.5和Al65Si10Cu20Zn5两种急冷钎料钎焊L2纯铝和6063铝合金,研究钎焊接头的界面微观结构和力学性能.结果表明,急冷钎料钎焊接头由母材、界面区和钎缝中心组成.界面区为αAl固溶体,钎缝中心组织为αAl固溶体 θ(Al2Cu)相 Si相.采用Al65Si10Cu20Zn5急冷钎料钎焊的接头抗剪强度均高于Al70Si-7.5Cu20Zn2.5急冷钎料钎焊的接头强度;匹配氯化物钎剂钎焊的接头强度均高于氟化物钎剂.在相同的工艺条件下,采用急冷钎料钎焊的L2纯铝接头,其抗剪强度都明显高于相应的常规钎料,其增加值在40%左右.     

Zn基钎料钎焊镁合金AZ31B接头的钎缝物相及力学性能

以Zn基钎料对变形镁合金AZ31B进行了高频感应钎焊,研究了钎焊接头的钎缝物相及力学性能.采用扫描电镜、X射线衍射仪、X射线能谱分析仪等分析了钎焊接头的界面组织及钎缝物相,测试了钎焊接头的强度及钎缝组织的显微硬度.结果表明:钎料与母材发生界面反应,在钎缝中生成α-Mg,γ-MgZn相.钎焊搭接接头平均抗剪强度为55 MPa,对接接头平均抗拉强度为77 MPa.接头的主要断裂形式为沿晶脆性断裂,断裂主要产生在α-Mg+γ-MgZn共析体组织处和α-Mg基体与α-Mg+γ-MgZn共析体组织的界面处.     

电站变压器用Cu/Al过渡接线端子超声波液相钎焊工艺及组织性能研究

本文利用超声波液相钎焊技术实现了变压器Cu/Al过渡接线端子的有效连接,当超声波功率P=300W、钎焊时间t=4s、钎焊温度为T=330℃时,能够获得良好的钎焊接。钎焊界面在Al/钎缝和Cu/钎缝侧均呈现良好的界面结合,未发现存在显著的焊接缺陷,钎缝硬度与Al基体硬度分布较为接近,没有显著的高硬度区存在。     

保温时间对铝/铜钎焊接头界面化合物和力学性能的影响

采用Zn-22Al钎料配合KAlF4-CsAlF4无腐蚀钎剂,在不同保温时间下对铝/铜进行炉中钎焊,研究了保温时间对钎焊接头、微观组织形貌,铜侧界面元素分布以及接头力学性能的影响.结果表明,随着保温时间的延长,Al/Cu接头Cu/钎缝界面CuAl₂化合物由层片状逐渐转变为树枝状并向钎缝内部生长;钎缝中的CuAl₂相由粗大块状转变为长条状或薄片状;Cu/钎缝界面处Zn元素含量峰值在保温时间为2 min时出现在铜母材与AlCu化合物之间,随着保温时间延长,Zn元素峰值逐渐向钎缝内部迁移.同时,铝/铜钎焊接头的抗剪强度随保温时间延长先提高后降低.     

Zn-Al钎料成分对Cu/Zn-Al/Al钎焊接头界面结构及性能的影响

分别采用Zn-15Al,Zn-22Al,Zn-28Al,Zn-37Al和Zn-45Al钎料钎焊获得Cu/Al接头.利用SEM,EDS和XRD研究了Zn-Al钎料成分对Cu/Al接头中Cu母材/钎缝界面结构的影响,并系统阐述了Zn-Al钎料成分-接头界面结构-接头抗剪切强度之间的关系.研究发现,Cu/Zn-15Al/Al接头中Cu母材/钎缝界面结构为Cu/Al4.2Cu3.2Zn0.7,且Al4.2Cu3.2Zn0.7界面层较薄,其厚度为2~3μm,接头具有较高的抗剪切强度,达66.3 MPa.随着钎料中Al含量的提高,在Cu/Zn-22Al/Al接头界面处Al4.2Cu3.2Zn0.7界面层的厚度逐渐增大,甚至在Cu/Zn-28Al/Al接头的Al4.2Cu3.2Zn0.7界面层附近出现少量的Cu Al2,接头的抗剪切强度逐渐降低.当采用Al含量较高的Zn-37Al钎料钎焊Cu/Al接头时,Cu母材/钎缝界面结构转变为Cu/Al4.2Cu3.2Zn0.7/Cu Al2;脆性Cu Al2层的出现,使接头抗剪切强度大幅下降,为34.5 MPa.当采用Al含量最高的Zn-45Al钎料钎焊Cu/Al接头时,Cu母材/钎缝界面结构转变为Cu/Cu Al2,接头抗剪切强度最低,为31.6 MPa.     

工艺参数对Cu/Al超声波液相钎焊接头成形及性能影响

利用超声波液相钎焊技术实现了变压器Cu/Al过渡接线端子的有效连接,当超声波功率P=300 W、钎焊时间t=4s、钎焊温度T=330℃时,能够获得良好的钎缝.钎焊界面在A1/钎缝和Cu/钎缝侧均呈现良好的界面结合,未发现存在显著的焊接缺陷,钎缝硬度与Al基体硬度分布比较接近,没有显著的高硬度区存在.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.