用Fe—Ti合金扩散连接SiC陶瓷

利用Ｆｅ－Ｔｉ合金在１４７３－１７２３Ｋ，０．９－５．４ｋｓ的接合条件下对常压烧结ＳｉＣ陶瓷进行了真空扩散连接，接头中形成ＴｉＣ，ＦｅＳｉ，Ｔｉ５Ｓｉ３反应相，试验结果表明，用Ｆｅ－５０Ｔｉ（ａｔ％）合金，在１６２３Ｋ，２．７ｋｓ的接合条件下，接头的高温（９７３Ｋ）剪切强度达到１３３ＭＰａ。     

快凝Al－Fe－M－Si合金的显微结构对熔体热历史的敏感性

研究了不同成分的快凝Ａｌ－Ｆｅ－Ｍ－Ｓｉ（Ｍ＝Ｔｉ，Ｎｂ，Ｃｒ＋Ｍｏ，Ｗ）合金显微结构对熔体热历史的敏感性．结果表明：在相同熔体热历史条件下，不同成分的快凝Ａｌ－Ｆｅ－Ｍ－Ｓｉ合金的显微结构有着明显差别；在１３２３Ｋ，５ｍｉｎ至１５２３Ｋ，５ｍｉｎ的熔体热历史制度范围内，只有快凝Ａｌ－Ｆｅ－Ｗ－Ｓｉ合金显微结构对熔体热历史比较敏感．作者认为合金过热熔体的微观不均匀区的大小是影响快凝Ａｌ－Ｆｅ－Ｍ－Ｓｉ合金显微结构对熔体热历史的敏感性的主要因素．     

SiC陶瓷与TiAl基合金扩散连接接头的强度及断裂路径

进行了ＳｉＣ陶瓷与ＴｉＡｌ基合金（ＴＡＤ）的真空扩散连接,给出了接头的剪切强度,并采用ＳＥＭ、ＥＰＭＡ和ＸＲＤ分析了接头的断裂路径。结果表明,在１５７３Ｋ和０．３～２８．８ｋｓ的连接条件下,当连接时间较短时接头强度较高,如室温时为２４０ＭＰＡ,高温（９７３Ｋ）时为２３０ＭＰａ接头在（Ｔｉ５Ｓｉ３Ｃｘ＋ＴｉＣ）／ＴＤＡ界面处断裂。随着连接时间的增加,接头强度降低频接头的断裂路径也由造近ＴＡＤ的（Ｔｉ     

SiC/TiAl扩散连接接头的界面结构及连接强度

对常压烧结的ＳｉＣ陶瓷与ＴｉＡｌ金属间化合物进行了真空扩散连接。采用扫描电镜、电子和Ｘ射线衍射分析等确定了反应产物的种类和接头的界面结构,并用拉剪试验评价了接头的连接强度。研究结果表明：ＳｉＣ与ＴｉＡｌ扩散连接中生成了ＴｉＡｌ２、ＴｉＣ和Ｔ５Ｓｉ３Ｃｘ三种上,接头的界面结构为ＳｉＣ／ＴｉＣ／（ＴｉＣ＋Ｔｉ５Ｓｉ３Ｃｘ）／ＴｉＡｌ。在１５７３Ｋ和１．８ｋｓ的连接条件下,接头室温剪强度达到２４０ＭＰａ     

纳米晶Fe_(74.7-x)Cu_1Nb_xV_(1.8)Si_(13.5)B_9合金的磁性

本文报道Ｆｅ７４．７－ｘＣｕ１ＮｂｘＶ１．８Ｓｉ１３．５Ｂ９（ｘ＝１，１．５，２）纳米晶软磁合金的综合磁性。ｘ＝２的合金的高频铁损水平为：ｐ３／１００ｋ＝４６８ｋｗ／ｍ３：Ｐ２／２００ｋ＝７０６ｋＷ／ｍ３；Ｐ２／５００Ｋ＝３６２０ｋｗ／ｍ３和Ｐ０．５／１０００ｋ＝８１０ｋｗ／ｍ３优于Ｆｅ－Ｃｕ－Ｎｂ－Ｓｉ－Ｂ类纳米晶合金的水平所考察的三种合金铁损水平都大大优于功率优良的Ｍｎ－Ｚｎ铁氧体Ｈ７Ｃ４考察了起始磁化率的温度关系，观察到原始非晶样品出现两个尖锐的Ｈｏｐｋｉｎｓｏｎ峰，与此不同的是，在具有最佳磁性的样品中只出现第二Ｈｏｐｋｉｎｓｏｎ峰，用Ｔｈｏｍａｓ理论解释了这一现象。观察到高温下纳米α－Ｆｅ（Ｓｉ）晶粒系统的超顺磁行为，起始磁化率的温度关系符合Ｃｕｒｌｅ－Ｗｅｉｓｓ定律。     

Fe_（73．5）Cu_（1．0）Nb_（3．0）Si_（13．5）B_9纳米软

从Ｈｏｐｋｉｎｓｏｎ效应及Ｘ光衍射技术研究了Ｆｅ（７３．５）Ｃｕ（１．０）Ｎｂ（３．０）Ｓｉ（１３．５）Ｂ９纳米软磁合金的居里温度特性。随晶化退火温度Ｔａ的提高，合金中αＦｅ－Ｓｉ纳米晶相的居里温度提高，但低于相同Ｓｉ含量下的常规Ｆｅ－Ｓｉ合金，且与显微组织结构有关，当Ｔａ较低时，合金中非晶相的居里温度与原始非晶合金基本相同。但其Ｈｏｐｅｉｎｓｏｎ峰宽化，Ｔａ＞７８３Ｋ后，其Ｈｏｐｋｉｎｓｏｎ４消失，无法判断居里温度。认为居里温度的上述特性与合金晶粒的小尺寸特性及元素成分分布特性有关。     

添加Cr和Ti对Fe－Al－Si合金耐磨性和磁特性的改善

添加Ｃｒ和Ｔｉ对Ｆｅ－Ａｌ－Ｓｉ合金耐磨性和磁特性的改善含Ｓｉ９．６％和Ａｌ５．４％的Ｆｅ－Ａｌ－Ｓｉ合金（仙台合金）具有优良的磁特性和高的硬度（Ｈｖ４５０～５００），是磁带录象机磁头用的良好材料。但在湿度高的夏季与磨损性高的磁带配合使用时这种合金磁...     

SiC陶瓷与TC4钛合金反应钎焊的研究

采用Ｃｕ箔对常压烧结的ＳｉＣ陶瓷与ＴＣ４钛合金进行了接触反应钎焊,并对接头的微观组织,形成机理和室温强度进行了研究。结果表明,利用Ｃｕ箔可以在低于其熔点的温度实现ＳｉＣ与ＴＣ４钛合金的连接。接头界面具有明显的层状结构,即由Ｔｉ－Ｃｕ－Ｓｉ合金层,Ｔｉ－Ｃｕ合金层和富Ｔｉ的Ｔｉ－Ｃｕ－Ａｌ合金层组成。在１２７３Ｋ的条件下连续５ｍｉｎ,接头室温关照切达到１８６ＭＰａ。     

Fe73.5Cu1Nb3Si13.5B9非晶合金电脉冲处理与等温退火的比较

用直流高密度电脉总和可比等温退火处理Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９非晶合金,并用ＸＲＤ,ＴＥＭ和穆斯堡尔谱方法进行了结构检测。结果表明,在电脉冲作用下,Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｐ９非晶合金在平均温度为４２０℃的条件下发生了纳米晶化,晶化度试样中无Ｆｅ－Ｂ相析出,无ＤＯ３型有序结构;晶化总量达３０．９％的无序ａ－Ｆｅ（Ｓｉ）相的平均尺寸为８～９ｎｍ,按二项式分布计算ａ－Ｆｅ（Ｓ     

Cu-Ni-Ti合金钎料对Si_3N_4陶瓷的润湿与连接

采用座滴法研究了Ｃ４－Ｎｉ－（２７—５６）Ｔｉ合金（原子分数,％,下刚在Ｓｉ３Ｎ４陶瓷上的润湿行为选用真空熔炼合金Ｃｕ３８Ｎｉ３０Ｔｉ３２和Ｃｕ３４Ｎｉ２７Ｔｉ３９作为钎料时,获得的Ｓｉ３Ｎ／Ｓｉ３Ｎ４接头的强度不理想在降低钎料含Ｔｉ量的同时适当降低含Ｎｉ量,重新设计了两种Ｃｕ－Ｎｉ－Ｔｉ（Ｓｉ,Ｂ）合金钎料,并采用膏状形式改善针料成分的均匀性,在１３５３Ｋ,１０ｍｉｎ的针焊条件下获得的Ｓｉ３Ｎ４／Ｓｉ３Ｎ４接头最高三点弯曲强度分别提高至３３８．８和２０６９ＭＰａ,并对Ｓｉ３Ｎ４／Ｓｉ３Ｎ。接头的界面反应进行了分析     

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.     

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。     

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).     

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.     

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.