大尺寸铝基复合材料锭坯的喷射共沉积制备技术及装置

为了解决陶瓷颗粒增强铝基复合材料大直径厚壁管坯、圆柱锭坯和环件的制备技术问题,作者发明了坩埚移动式自动化控制喷射共沉积技术和一系列装置,研究了喷射共沉积过程原理及基本规律,制备出了尺寸为dout650 mm/din 300 mm×1 200 mm的6066Al/SiCp管坯,d700mm×600 mm的7075Al/SiCp圆柱锭坯和dout1 200mm/din600 mm×250 mm的7075Al/SiCp环件.沉积层的冷速达104K/s.在沉积过程中雾化颗粒的沉积轨迹是一种有规律的扭合曲线.实验结果表明,该技术是适合于制备大尺寸快速凝固铝基复合材料坯件的理想技术.     

喷射沉积7075/15SiCp铝基复合材料高温拉伸变形与断裂行为

在300～450℃和0．001～0．1s6-1的条件下,对喷射沉积7075／15SiCp铝基复合材料板材的高温拉伸变形与断裂行为进行了研究，用扫描电镜（SEM）观察拉伸断口。结果表明，流变应力随温度的升高而下降，表现出相当的应变软化直至断裂。伸长率随着温度的升高和应变速率的降低而增加，但其应变速率敏感系数最大值仅为0．24,表明不存在超塑性，变形激活能为379kJ／mol，比基体7075铝合金变形激活能高。拉伸断裂行为主要由延性断裂机制控制，其基体金属可见大量局部塑性变形特征，无界面滑移是导致喷射沉积7075／SiCp复合材料过早断裂而不出现超塑性的主要原因。     

喷射共沉积7075/SiCp复合材料薄板的轧制成形

研究了轧制方式、轧制温度等对喷射共沉积7075/SiCp复合材料挤压板材成形性能、显微组织和力学性能的影响.结果表明:挤压变形可以提高7075/SiCp喷射共沉积坯的轧制变形性能,平行于挤压方向取样并进行交叉轧制可以制备出高质量、高性能的薄板;轧制变形对挤压过程中形成的SiC颗粒条带状不均匀分布有显著的改善作用,随着轧制变形量的增加,SiC颗粒分布趋于均匀;轧制过程中,SiC颗粒破碎,尺寸明显变小,形貌呈钝化趋势;7075/SiCp复合材料薄板(T6态)的力学性能为:σs＝536.2MPa,σb＝670.2MPa,δ＝4.8%.     

喷射沉积7075A1／SICp铝基复合材料板材的高温拉伸变形行为

当温度为300-450℃，应变速率为0．001-0.1S^-1时，在WDW-E200拉伸机上采用单向拉伸实验研究喷射沉积7075A1／SIC。复合材料板材的高温变形行为；分析板材的变形激活能以及流变应力、变形温度和应变速率之间的关系。结果表明：随着变形温度升高和应变速率降低，7075AI／SiCp复合材料板材拉伸流变应力减小；其最大拉伸断裂伸长率由5．03％增加到71．07％；7075A1／SICp复合材料板材应变速率敏感系数的最大值仅为0．22，在温度为623、673和723K时其变形激活能分别为380．49、323．42和434．S6kJ／mol，均高于铝的晶格自扩散激活能（142kJ／mol）。     

喷射沉积7075/SiCp复合材料的压缩变形和断裂规律研究

研究了喷射沉积7075/SiCp复合材料高温压缩时的变形和断裂规律。结果表明,增大试样表面的摩擦阻力,并适当提高变形温度可有效促进致密化过程。接触面上的摩擦系数、变形程度和试样初始高径比越大,则鼓度越大。喷射沉积7075/SiCp复合材料高温压缩时的断裂方式主要有四种,即空洞在增强相与基体界面处形成而出现增强相从基体中拔出的现象、空洞在基体中形核长大而引起基体的延性断裂、颗粒团聚处的断裂和颗粒的脆性断裂。随着变形温度的升高,喷射沉积7075/SiCp复合材料的断裂应变迹线的截距先增大后减小,420℃压缩时截距达到最大值;润滑可使断裂应变迹线上移,变形安全区增大;随着坯料的相对密度增大,变形断裂区减小。     

热挤压喷射沉积Al-SiCp复合材料中SiC分布特征研究

采用多层喷射共沉积工艺制备了SiCp/Al复合材料锭坯。以不同挤压比对其进行热挤压变形,研究了挤压变形对SiC增强颗粒分布特征的影响。结果表明:喷射沉积制坯过程中,SiC颗粒主要粘附于合金液滴的表面,造成SiC颗粒在合金液滴表面较多,内部较少,使SiC颗粒呈现层状分布特征。在挤压变形的三向应力作用下,这种层状分布特征难以消除。SiC颗粒在挤压棒材中呈条带状流线分布,横截面上则呈"年轮"分布特征。增大挤压比,挤压棒材中SiC颗粒的分布趋于均匀。     

喷射沉积7075Al/SiCp铝基复合材料板材的高温拉伸变形行为

当温度为300～450℃,应变速率为0.001～0.1 s-1时,在WDW-E200拉伸机上采用单向拉伸实验研究喷射沉积7075Al/SiCp复合材料板材的高温变形行为;分析板材的变形激活能以及流变应力、变形温度和应变速率之间的关系.结果表明:随着变形温度升高和应变速率降低,7075Al/SiCp复合材料板材拉伸流变应力减小;其最大拉伸断裂伸长率由5.03%增加到71.07%;7075Al/SiCp复合材料板材应变速率敏感系数的最大值仅为0.22,在温度为623、673和723 K时其变形激活能分别为380.49、323.42和434.56 kJ/mol,均高于铝的晶格自扩散激活能(142 kJ/mol).     

SiC_p/Cu合金电子封装壳体半固态成形模拟

采用有限元软件Deform-3DTM对SiCp/Cu合金电子封装壳体的触变成形过程进行了数值模拟。对触变成形过程中坯料的单元体网格变化、金属流动速度场、等效应力场及挤压杆速度对等效应力的影响等进行了分析。模拟结果表明,在半固态温度为910℃、挤压杆速度为100mm/s时,可以得到SiCp含量较高且分布较均匀的SiCp/Cu合金电子封装壳体,且能满足电子封装壳体的要求。     

雾化器往复扫描喷射共沉积制备6066/SiCp坯锭技术

提出了雾化器往复扫描喷射共沉积制备6066／SiCp的装置和方法，并与传统的喷射共沉积装置进行了比较。采用了螺旋给料陀螺负压引流乏气送粉装置和分离式双环缝雾化器来加入SiC颗粒增强相，制备了大规格的6066／Sicp复合材料坯锭。     

挤压态喷射沉积7075Al/SiC颗粒增强复合材料热压缩流变应力行为及加工图（英文）

在Gleeble-1500热模拟机上对挤压态喷射沉积7075Al/15%Si C颗粒增强复合材料进行热压缩试验,变形温度为300~450°C,应变速率为0.001~1 s-1。结果表明:复合材料的真应力-真应变曲线几乎呈现快速流动软化特征,没有明显的加工硬化;其应力值随着变形温度的增加和应变速率的减小而减小,且当变形温度在400°C以下时,其应力水平较喷射沉积态基体7075Al合金的高,但在450°C时,其应力水平比基体合金的低。当变形温度在450°C和应变速率为0.001~0.1 s-1时,其应变速率敏感系数达0.72,呈现超塑性变形特征。加工图以及金相显微组织观察表明:该复合材料最合适的热加工参数为变形温度430~450°C,应变速率0.001~0.05 s-1。     

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。