铝合金支架压铸件局部增压工艺的研究

介绍了铝合金支架压铸件结构特点及品质要求，其难点为铸件在4个安装支脚处的内部品质控制，要求其内部品质达到孔隙率D5的要求。在压铸模设计中采用局部增压技术，对局部增压的工艺参数包括挤压压力、挤压时间、挤压行程，采用正交试验方法，进行工艺优化。最终确定优化的工艺参数：挤压压力为300 MPa,挤压开始时间为1.0 s,挤压杆的挤压行程为8 mm。优化后的挤压参数经批量生产验证，铸件孔隙率能够满足D5要求。     

启锻时间对铸锻复合成形2014铝合金组织与性能的影响

研究了不同的启锻时间对2014铝合金的组织与性能的影响。结果表明,当启锻时间为4~5s时,制件的组织致密,施加的锻压力有效地对铸坯进行了强制补缩;与锻头接近的部位都存在明显的变形组织,随着启锻时间的延长,制件中的晶粒尺寸增大。热处理前后制件的抗拉强度和伸长率随着启锻时间的延长先增大然后减小,接着又增大。未热处理状态下,启锻时间为4s时,其力学性能最高,抗拉强度和伸长率分别为280MPa和8.5%;热处理后,启锻时间为5s时,其力学性能最高,抗拉强度和伸长率分别为380 MPa和6.5%。     

电场升温速率对成型Ti6Al4V钛合金微齿轮的影响

采用电场辅助微塑性模锻成形技术,用于成型高强度、大硬度、低塑性的Ti6Al4V钛合金微齿轮。实验结果表明,在电场作用下,圆柱形Ti6Al4V坯料在石墨模具中可以成型微齿轮。Ti6Al4V材料在加热速率为5℃/s时具有最佳的可成型性,较高的加热速率30℃/s和40℃/s可以有效地缩短材料预变形的时间。经电场辅助成型的样品均具有魏氏结构,但齿顶比齿心的组织更细小。加热速率为5℃/s和10℃/s的试样β相含量略高于原始坯料,但加热速率为20℃/s、30℃/s和40℃/s的试样没有显示出β相。此外,在电场作用下,所有成形样品的维氏硬度均有所增加。     

微沟槽热管等离子弧焊接封口工艺研究

在微沟槽热管(MGHP)制造过程中,管端焊接封口工艺是最关键环节之一,用等离子弧焊(PAW)方法可有效解决其封口问题.本文从焊接距离S、氩气流量Q、同步转速N、焊接电流I与时间t等因素对MGHP的PAW焊接封口工艺进行研究,结果表明,获得良好稳定焊接封口质量的最佳工艺参数为:S=3mm;Q=0.36L/min;N=80r/min;各阶段的电流、时间为,I1=5A,t1=0.10s;I2=45A,t20.40 s;I3=35A,t3=0.40s;I4=45A,t4=0.40s.     

铁素体球墨铸铁与20钢的闪光对焊

试验使用铁素体球墨铸铁和20钢的实心棒料进行了闪光对焊，通过改变次级电压4～8级，通电时间3～5s，观察其焊接接头组织的变化并测定其抗拉强度。结果表明，接头由三个区组成；当通电时间一定时，抗拉强度随次级电压的升高先减小后增大；当次级电压一定时，抗拉强度随通电时间的增加而增大。在次级电压为8级、通电时间为5s时，抗拉强度达最大值，为370．8MPa，是20钢母材的90.4％，是球墨铸铁母材的83.7％。     

高频熔炼制备Al2O3陶瓷颗粒增强耐热钢基复合材料

陶瓷／金属基复合材料由于结合了两者的性能优点，因而应用前景巨大。研究工作采用高频加热熔炼结合负压铸渗工艺，制备了适合于高温摩擦磨损工况下使用的Al2O3陶瓷／耐热钢基表层复合材料，分析了高频加热熔炼温度、加热时间的控制和吸铸时间对铸渗层深度的影响。结果表明，高频加热阳压为7．5kV的加热功率，加热时间为60s，金属液加热温度在1560℃左右，真空吸铸时间为4～5s的制备工艺可获得较好表层复合材料，复合材料界面结合良好，陶瓷颗粒分布比较均匀。     

用于老年人安全检测的可穿戴式惯性开关的研制

为了满足日常生活中老年人安全监护的要求,设计了一款用于跌倒检测的万向可穿戴式惯性开关。利用Ansys软件对惯性开关进行动态仿真分析,结果表明:惯性开关在空间任意方向的阈值加速度为4.24g,接触时间大于200μs,具有良好的接触性能。采用UV-LIGA叠层光刻和精密微电铸工艺制作惯性开关,并利用落锤试验对惯性开关进行动态测试,结果表明:在大于5g阈值加速度作用下惯性开关可实现闭合的功能,接触时间大于100μs,能够满足应用要求。     

温度对铝硅合金螺旋振动抛光酸洗效果的影响

研究了不同温度下,不同配比、不同酸洗时间对酸洗的影响,发现冬季室温下酸洗的工艺为:HNO3∶HF＝1∶2,时间8 min;夏季室温下酸洗工艺为:HNO3∶HF＝2∶1,时间20 s;春秋季室温下酸洗工艺为:HNO3∶HF＝5∶4,时间为40 s.     

热成形加热新技术

针对常规连续辊底炉的能耗高、维护成本高的缺点,提出了多层箱式炉的设计方案;针对常规加热方式的奥氏体化时间长、易氧化的缺点,依次研究了直接通电加热、感应加热和直接热传导加热3种新的热冲压加热成形工艺技术。直接通电加热具有加热速度快(可达250 ℃/s）、热效率高、能耗低、氧化少、成形后组织均匀,硬度高的特点,并可用于局部加热及不等温加热处理;通过合理配置和设计感应加热器的组合,可以实现奥氏体化35 s,总加热时间在35 s到60 s之间,加热速率最大可达到200 ℃/s,温度偏差控制在10 ℃之内;直接传导加热方式,在炉时间从传统炉的5~7 min减少到20~40 s,装置占地小,加热速度和加热温度可调范围宽、调节速度快,可满足不同系列要求的热冲压工艺需要。     

VPS-EBW法制备W／Cu功能梯度材料及热负荷实验研究

采用真空等离子体喷涂-电子束焊接法制备出核聚变面对等离子体W／Cu功能梯度材料，梯度材料中成分分布均匀、密度较高。电子束辐照热负荷实验发现：8MW／m^2的热负荷条件下，样品可以承受20s的辐照：在2．5Mw／m^2，4．5MW／m^2，6MW／m^2的热负荷条件下，样品可分别承受26s，22s，20s的辐照而没有出现明显的损伤现象。样品疲劳实验也表现出很好的性能：8MW／m^2，10s辐照，可以承受70周热疲劳：6MW／m^2，20s辐照，在第90周裂纹开始形成；在2．5MW／m^2，辐照时间为30s和4．5MW／m^2，辐照时间为25s条件下，样品经过100周热疲劳实验均没有出现明显的损伤现象。对已出现裂纹的断面作X射线能量色散能谱（EDS）分析发现，由于焊料本身或者焊接时引入的杂质和虚焊，导致材料承受较高热负荷实验时的热应力迅速增大到破裂极限，使表面温度快速升高，而导致材料连接失效。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.