定向凝固Al2O3／Al—4.5Cu复合材料显微组织与合金元素的分布

利用ＺＭＬＭＣ定向凝固装置,研究了Ａｌ２Ｏ３／Ａｌ－４．５Ｃｕ金属基复合材料在不同凝固冷却速度条件下的显微组织和合金元素分布的变化,实验结果表明：当凝固速度ｖ＝１６．７μｍ／ｓ时,Ａｌ２Ｏ３／Ａｌ－４．５Ｃｕ复合材料基体组织为胞状晶,胞状晶中无颗粒存在;当ｖ＝４９．８μｍ／ｓ时,基体为树枝状晶,颗粒在枝晶中均匀分布,一二,次枝晶间距随着凝固速度的提高而减小。     

Zn-2%Cu包晶合金定向凝固的微观组织

对 Ｚｎ－２％Ｃｕ包晶合金进行了定向凝固实验研究，考察了在不同凝固速度条件下获得的凝固组织，并对其组织构成及尺度分布进行了分析 结果表明，组织从低速到高速经历了棒状胞晶—等轴晶—列状胞晶—板状胞晶—共生结构的转变，其中高速组织特征间距λ与凝固速度ｕ之间存在λ·ｖ０．５４７７＝５５０．５的关系，与低速胞晶组织相比较有显著差异；同时在没有出现平界面生长的条件下获得了包晶共生生长组织，由此对包晶共生生长的平界面假设提出了质疑。     

Al—0.53Zn合金近快速定向凝固条件下的胞晶间距选择

利用Ｂｒｉｄｇｍａｎ装置考察了Ａｌ－０．５３Ｚｎ单相合金在近快速定向凝固条件下的胞晶间距选择规律。结果表明：在给定的温度梯度下,随着生长速度的增大,定向凝固组织均为胞状晶、胞晶间距λ的分布存在一个较宽范围,其最大,最小及平均间距随生长速度ｖ变化的实验规律可为：λｍａｘ＝９４８．５１ｖ＾－０．４９６１,λｍｉｎ＝６６１．１６ｖ＾－０．５０１５,λ＾－＝４１２．４１ｖ＾－０．５０４９。ＫＧＴ理论模型较     

高温度梯度定向凝固振荡性微观结构的特征和开成机制

利用新型高温梯度（ＧＬ＝２５６－１３００Ｋ／ｃｍ）定向凝固装置，研究了粒晶法制备含亚结构的镍基高温合金ＤＤ３单晶及二元模型合金Ａｌ－０．８５％Ｃｕ晶体生长过程的组织演化与选择特征中的非稳态组织特性，特别是定向胞状振荡性微观结构的组织特性及其与定向凝固江艺条件的关系，并将其与在晶体生长透明有机物模拟装置－Ｊａｃｋｓｏｎ温度平台（ＧＬ可达１５０Ｋ／ｃｍ）上原位观察到的ＣＢｒ４定向生长结果相对比，从而分     

Al70—xCu8Fe10Cr12Cex准晶合金的凝固形貌及组织

研究了Ｃｅ对ＡｌＣｕＦｅＣｒ准晶合金凝固特性的影响。结果表明加入Ｃｅ能提高ＡｌＣｕＦｅＣｒ合金的硬度，加入适量的Ｃｅ可细化晶粒；而且固液界面的生长方式随着Ｃｅ含量的增加而明显改变，使合金凝固形貌表现出由胞状晶向胞状枝晶再向树枝晶转变的规律     

凝固速率对定向凝固合金DZ22枝晶臂间距和枝晶偏析的影响

采用新研制的超高梯度定向凝固装置，研究了不同凝固速率下定向凝固高温合金ＤＺ２２枝晶臂间距和枝晶偏析。结果表明，冷运速率增大，枝晶臂间距显著细化，枝晶偏析被强烈抑制。当冷运速率为５２．４Ｋ．ｓ＾－１时，一次、二次枝晶臂间距λ１和λ２分别为２８．８和８．４μｍ，Ｎｂ，Ｔｉ，Ａｌ，Ｃｒ，Ｃｏ，Ｗ等元素的偏析比均趋近于１。     

Al－Cu－Co－Ge十边形准晶单晶的定向生长

利用控制凝固过程的定向凝固技术生长出了直径０．８长１０ｍｍ的Ａｌ－Ｃｕ－Ｃｏ－Ｇｅ十边形准晶单晶．在准晶生长过程中，所有准晶单晶形成了单一取向的择优生长结构，其棱柱的中心轴为十次旋转对称轴．在温度梯度为９５℃／ｃｍ的条件下，随着定向凝固速度的增大，生长界面出现的成分过冷越来越大，从而导致生长界面的扰动也逐渐加剧并使成分偏析，界面形态由平面向胞状和树枝状转化，出现大量非准晶相，最后无法生长出所需要的高质量准晶单晶．     

Zn-Cu包晶系中的片层状类共晶组织

采用Ｂｒｉｄｇｍａｎ定向凝固法研究了不同生长速度下Ｚｎ－３．３７％Ｃｕ（质量分数）包晶合金的凝固过程及其组织形态．当生长速度高于１．０ｍｍ／ｓ时,出现片层状类共晶生长,且片层间距和生长速度的关系很好地符合λｖ１／２＝（２１６±４２）μｍ３／２·ｓ－１／２关系,该数值与多数共晶系相比偏高．这类共晶组织在包晶合金中的发现有助于对包晶合金凝固过程的进一步研究．     

Zu—Cu包晶系中的片层状类共晶组织

采用Ｂｒｉｄｇｍａｎ定向凝固法研究了不同生长速度下Ｚｎ－３．３７％Ｃｕ（质量分数）包晶合金的凝固过程及其组织形态。当生长速度高于１．０ｍｍ／ｓ时,出现片层状类共晶生长,且片层间距和生长速度的关系很好地符合λｖ＾１／２＝（２１６±４２）μｍ＾３／２·ｓ＾－１／２关系,该数值与多数共晶系相比偏高。这类共晶组织在包晶合金中的发现有助于对包晶合金凝固过程的进一步研究。     

Al—4.5Cu单晶定向凝固一次枝晶间距研究

采用Ａｌ－４．５Ｃｕ单晶进行台阶变速定向凝固实验，考察了金属合金中一次枝晶间距随凝固生长速度变化的动态响应规律，结果表明，对于确定的凝固控制参数，稳态一次枝晶间距选择一个较宽的容许分布范围，同时，平均一次间距的选择也是凝固系统所经历的历史显著地相关，实验结果很好支持了Ｈｕｎｔ－Ｌｕｅ提出了枝晶生长一次间距的下限模型。     

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.