急冷Ni-Cr-B合金箔带钎料的制备及其可焊性

采用液态急冷单辊法制备了急冷Ni-Cr-B中间合金箔带。利用DSC ,XRD和SEM等方法对急冷Ni-Cr-B合金箔带的固液相线的温度 ,结构及成分分布进行了研究。利用液态金属表面张力仪测定了急冷Ni-Cr-B合金箔带在镍基高温合金上的润湿性。并采用此中间合金对镍基高温合金进行了瞬态液相连接 (TLPBonding) ,测定了连接后的试棒在 10 10℃ / 2 48MPa下的持久寿命。结果表明 ,制备的Ni-Cr -B合金箔带成分均匀 ,熔点适于TLP连接。液态钎料对镍基高温合金基体具有良好的润湿性。采用这种中间合金对镍基高温合金进行TLP连接后的接头持久性能接近于母材     

Au-20.1Ag-2.5Si-2.5Ge新型中温钎料的组织与性能

选择成分（质量分数，％）为Au-20．1Ag-2．5Si-2．5Ge的中温钎料合金，采用中频感应真空熔炼法制备钎料合金铸锭，分别利用DTA、SEM对钎料合金的熔点及显微组织进行分析，并初步研究钎料与Ni的润湿性。结果表明，钎料合金的熔化温度区间为451．36-506．49℃；钎料合金形成了α＋β共晶组织，由于Si、Ge同时加入，共晶组织变质为细小分散的共晶体；钎料合金具备优良的可加工性以及与Ni具有良好的润湿性，且在焊接界面钎料合金已与Ni合金化形成金属间化合物。     

Al-Si-Cu-Ni低熔点钎料中合金元素对其性能的影响

Al-Si钎料因具有良好的润湿性、流动性、钎焊接头的抗腐蚀性和可加工性，应用非常广泛，但其熔点较高，很难用于低熔点的铝合金的钎焊。以Cu、Ni作为主要的添加元素，通过正交试验的方法研究了合金元素Cu、Ni、Si对铝基钎料熔点的影响。结果表明，影响的主次顺序为Cu、Si、Ni，同时得出：随着合金元素Cu、Si的含量的增大，其熔点大大降低；合金元素Ni的含量对钎料熔点的影响较小。钎料Al-20Cu-3.3Ni-10Si的熔点最低，达到535.8℃，同时该钎料的铺展性能极佳。     

Cu-P基急冷钎料的制备及钎焊性能的研究

利用单辊急冷法制备用于铜及铜合金钎焊的Cu76.3P7.5Ni13Sn3Si0.2铜磷基急冷钎料。制得的急冷铜磷基钎料薄带具有良好的韧性,钎焊性能优良。将急冷钎料在680℃的钎焊温度下选择3种保温时间(5、10、15 min)与紫铜进行真空钎焊,重点研究了急冷钎料的润湿性与保温时间的关系以及焊接接头的组织结构及力学性能。结果表明,急冷钎料的熔化温度低,润湿性好,硬度低、易加工,用急冷钎料焊接的接头有较优的接头质量。     

基于低银钎料的金刚石薄壁钻钎焊工艺研究

根据Ag、Cu、Zn、Cd、Ni、Co、Mn等元素在钎料中的作用和特点,通过分析和选择,研发了一种新型钎料,并对其熔点、强度以及钎焊工艺进行了研究.结果表明:新开发的低银钎料ZB-1中的表面活性元素能显著降低液态钎料的表面张力,细化合金晶粒,延缓钎焊过程中钎料的氧化,在改善钎料润湿性的同时净化钎缝晶界,从而提高钎缝的抗...     

合金元素Cu,Si,Ni对Al基钎料的影响

A1—Si钎料因具有良好的润湿性、流动性、钎焊接头的抗腐蚀性和可加工性，应用非常广泛，但其熔点较高，很难用于低熔点铝合金的钎焊。本文以Cu，Ni作为主要的添加元素，通过正交试验的方法研究了合金元素Cu，Ni，Si对A1基钎料性能的影响。结果表明，随着合金元素Cu，Si的质量分数的增加，其熔点大大降低；同时钎料的铺展性能也有所改善；合金元素对钎焊接头强度的影响规律不明显。     

Au-20Sn合金的急冷制备及钎焊性能

用单辊旋淬法制备了Au-20Sn合金薄带钎料,利用差示扫描量热分析(DSC)、X射线衍射分析(XRD)及场发射扫描电镜(FESEM)等方法对合金的熔化特性、相组成及显微组织进行了观察分析,并研究了与Cu、Ni基材的焊接性能。结果表明,急冷钎料合金熔化温度低于共晶点且随铜辊转速发生变化,铜辊转速越快,熔点越低,急冷合金显微组织细小均匀,棒状或卵状δ-AuSn相分布于基体组织上,晶粒尺寸可达纳米级;急冷法抑制了脆性相ζ’-Au5Sn的形成,改善了合金塑性性能;急冷钎料薄带与Cu、Ni基材表面润湿优良,在Cu基材上扩散距离更远,形成无针状组织析出的界面层;与Ni形成疏松的颗粒状IMC层;Cu基体的焊接接头抗剪强度高于Ni基体。     

Ag和Ni元素对Sn-Sb-Cu无铅钎料熔化温度和铺展性能的影响

在Sn-Sb-Cu三元钎料合金中添加微量元素Ag和Ni,通过合金化形成Sn-Sb-Cu-Ag和Sn-Sb-Cu-Ni两种新型四元无铅钎料合金,以改善基体钎料性能.结果表明,在Sn-Sb-Cu钎料合金中添加微量元素Ag,合金熔化温度较基体钎料下降,铺展面积增大,这与钎料过热度增大,形成弥散低熔点相SnAg和液态钎料表面张力减小有关;添加微量元素Ni,合金熔化温度较基体钎料下降,铺展性能稍稍变差,这是因为添加微量元素Ni后,Sn-Sb-Cu-Ni液态钎料粘度提高,表面张力增大.且在钎料与铜基板处形成了多面体形状(Cu,Ni)6Sn5,且该相覆盖在Cu6Sn5表面,不利于液态钎料的润湿铺展.     

钛/钢异种金属感应钎焊钎料及其工艺性能的研究

研制了钛/钢异种金属高频感应钎焊用四元合金钎料Ag45CuZn3.5Ni.对所制备的不同Ni含量的系列四元合金钎料进行了熔点测定、润湿性以及工艺性能的对比试验.SEM微观组织分析和力学性能测试结果表明,Ni与Ti的化合有效地阻止了Ti-Fe金属间化合物的产生.Ag45CuZn3.5Ni合金钎料可获得剪切强度相对较高的接头.     

新型Ag-Cu-Ge钎料的性能及钎焊界面特征

根据Ag-Cu-Ge系三元相图,制备了Ag-Cu33.4-Ge28.1,Ag-Cu43-Ge20(质量分数,%)两种中温合金钎料。利用金相显微镜、DTA对钎料组织及其熔点进行分析,并对其润湿性进行测试。结果表明:两种合金钎料的熔化温区为539~622℃,Ag-Cu33.4-Ge28.1合金对于纯Ni和Cu具有良好的漫流性和润湿性。利用扫描电镜和能谱仪对钎焊后的界面微观组织进行观察与分析,发现在界面处形成了固溶体和金属间化合物。     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.