渗钐对TiNi形状记忆合金线性回复性能的影响

本文论述了形状记忆合金线性回复行为的新概念,定义了线性回复行为的相关性能指标.以氢化钐为渗剂,在真空炉中对TiNi形状记忆合金弹簧进行稀土表面渗入化学热处理,研究了渗钐(Sm)对其线性回复性能的影响.实验结果表明在550℃真空条件下对TiNi形状记忆合金弹簧渗钐(Sm)4小时,能得到厚度约为2μm的渗层,渗层中含有金属间化合物NiSm,从而显著改善其线性回复性能;线性回复温度范围Tw从4℃拓宽到8℃,线性回复率η从54%提高到75%,线性回复程度PL从56%提高到70%,非线性回复程度Ps从44%减小至10%,但总回复程度PT有所下降.     

热处理及训练对NiTi形状记忆合金弹簧双向记快效应的影响

形状记忆合金作为双程驱动元件时通常是与一偏压元件同时使用来实现双程驱动[1,2].本文通过不同热处理制度对TiNi形状记忆合金的弹簧相变点和形状恢复率的影响以及训练次数对形状恢复率的影响研究,以期获得性能良好的双向记忆合金弹簧单独作为双向驱动元件的最佳处理条件.结果表明经450℃热处理并经过20次训练得到的TiNi形状记忆合金弹簧是最优的.     

钎焊温度对TiNi形状记忆合金性能和组织的影响

TiNi形状记忆合金力学性能和组织对温度变化极为敏感。通过改变加热温度，研究了TiNi形状记忆合金的力学性能和组织变化规律。结果表明：加热温度对TiNi形状记忆合金的抗拉强度和超弹性影响较大。TiNi形状记忆合金力学性能变化存在着两个临界转变温度。温度高于650℃，抗拉强度降低；温度高于200℃，超弹性降低。组织由B19相已部分转变为B2相。     

TiNi形状记忆合金的特性及应用

形状记忆合金的应用非常广泛，在医学方面，支架、导管、导引丝、血过滤器等医疗器件，已经越来越广泛地采用TiNi形状记忆合金及超弹性合金制作；在工业领域，管接头及紧固件，驱动器，智能复合材料，阻尼材料，日常用品等各个方面，都可见到TiNi形状记忆合金的身影。1 医学方面的应用TiNi形状记忆合金在医学方面的应用始于70年代末，90年代得以迅速发展。其原因并不是TiNi形状记忆合金材料价格的下降，而是因为：（1）微创医疗技术的发展对新型医疗器件的需求增加，而这些新型医疗器件采用传统的材料难以制造；（2）TiNi 毛细管及其激…     

TiNi形状记忆合金与不锈钢的储能焊

采用储能焊焊接TiNi形状记忆合金与不锈钢异质接头，研究了两种母材及接头的力学性能，在光学显微镜、扫描电镜及能谱仪上观察分析接头的断口形貌和微观组织。结果表明：TiNi形状记忆合金与不锈钢异质接头的抗拉强度较低并且脆。由于不锈钢与TiNi形状记忆合金熔化，在接头处形成铸态组织及脆性化合物，改变了TiNi形状记忆合金成分和组织，异质接头的记忆效应和抗拉强度受到严重影响。为了提高异质接头的性能．焊接时应尽量避免各种缺陷并将焊缝中多余熔化金属挤出。     

时效处理对低间隙TiNi形状记忆合金超弹性的影响

研究了时效处理对低间隙TiNi形状记忆合金超弹性的影响。力学实验结果表明,分别经300℃×(60min-180min)及400℃×(10min~30min)时效处理后,TiNi形状记忆合金丝材抗拉强度均大于1000MPa,经6%应变加载-卸载后,残余应变量均小于0.31%。以上两种时效处理工艺后低间隙TiNi形状记忆合金线材具有良好的力学性能及超弹性。     

TiNi形状记忆合金与不锈钢激光钎焊AgCuZnSn钎料的研制

成功研制一种适合于TiNi形状记忆合金与不锈钢异质材料钎焊，并可安全应用于医学领域的新型AgCuZnSn银基钎料。对AgCuZnSn系钎料的熔化特性、微观组织、钎焊工艺特性及接头力学性能进行了研究。结果表明，所研制AgCuZnSn银基钎料成分为Ag51～53Cu21～23Zn17～19Sn7～9，固相线温度为590．0℃，液相线温度为635．3℃。该钎料主要由α—Ag固溶体、α-(Cu，Zn)固溶体和Ag-Cu共晶相组成，并含有少量Cu41Sn11、AgZn、Ag3Sn、Cu5Zn8等化合物。采用该钎料钎焊TiNi形状记忆合金与不锈钢，接头强度达320～360MPa，同时TiNi形状记忆合金性能损失较小。新型钎料熔点低、钎焊冶金特性优异，钎焊接头界面冶金结合平直、致密。     

形状记忆合金

Fe-Ni－Co-Al系形状记忆合金;Fe-Mn-Al-Ni系形状记忆合金;Fe-Mn-Ga系形状记忆合金;Fe=Ni—Co-Al-Ta系形状记忆合金;高Ni（55％（原子））钛镍形状记忆合金;电加热塑性变形后退火制度对TiNi合金结构和显微硬度影响;高温处理对TiNi基合金结构和性能的影响;高温处理对TiNi基合金结构和性能的影响     

热处理及训练对NiTi形状记忆合金弹簧双向记忆效应的影响

形状记忆合金作为双驱动元件时通常是与一偏压元件同时使用来实现双程驱动。本文通过不同热处理制度对TiNi形状记忆合金的弹簧相变点和形状恢复率的影响以及训练次数对形状恢复率的影响研究，以期获得性能良好的双向记忆合金弹簧单独作为双向驱动元件的最佳处理条件。结果表明在450℃热处理并经过20次训练得到的TiNi形状记忆合金弹簧是最优的。     

微电机系统用TiNi形状记忆合金薄膜特性

近来研究表明，形状记忆合金(SMA)薄膜有望用于微电机(MEMs)领域，因为SMA材料相变温度低，消耗能量小，循环动作时间短速度快。然而对SMA薄膜制备工艺及其性能，和使用具体要求等还了解的不多，如精确度控制、合金成分的影响、簿膜量、与微电机工艺相匹配的热处理工艺等。记忆合金最常用的材料是TiNi基SMA合金，用(100)硅片作载体，TiNi合金作靶材，在纯氩气中用射频磁控溅射法将TiNi涂层沉积到硅片上。涂层经923K退火1h，使涂层晶体化，X射线能谱分析表明TiNi簿膜成分为：50.5%Ti，49.5%Ni。簿膜晶粒在300nm~500nm，表面粗糙度…     

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.     

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。     

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.