板条状FCC／BCC相界结构和长大机制

魏氏体铁素体，上贝氏体和板条马氏体均是在过冷奥氏体板条状相变产物，它们的ＦＣＣ／ＢＣＣ相界都接近（１１１）ｔ密排面，本文用高分辨电镜在原子尺度上观察证实了板条马氏体相界台阶一位错结构，结合相变晶体学改进了板条马氏体和魏氏铁素体相界结构模型，这两个模型代表了（１１１）ｆ／（０１１）ｂ原子界面外延匹配可能的位错配置类型，同它们各自的长大动力学相容，贝氏体不可能上述二者之外的相界结构，应通过试验确定，它     

铁基合金马氏体的切变过程

根据铁合金中马氏体相变的Ｋ－Ｓ位向关系，提出了马氏体的形核长大相变位错模型，并推导出马氏体切变过程的数学表达式。这些表达式弥补了马氏体转变晶体学唯象理论（ＰＴＭＣ）的缺陷，对钢中马氏体亚结构（孪晶和位错）的形成提出了新的晶体学几何解释。     

贝氏体相变理论研究进展

总结了国内外贝氏体相变理论研究领域的主要研究成果、争论焦点和重大分歧，涉及贝氏体相变过程伴随的表面浮凸效应、相变产物晶体学、贝氏体铁素体的“中脊”和“边脊”、下贝氏体碳化物的析出形态等；研究了贝氏体碳化物的不同特殊析出形态和α／γ相界面的巨型台阶；提出贝氏体铁素体可能按置换型原子体扩散控制台阶机制长大。     

贝氏体相变理论研究进展

总结了国内外贝氏体相变理论研究领域的主要研究成果，急论焦点和重大分歧，涉及贝氏体相变过程伴随的表面浮凸效应，相变产物晶体学，贝氏体铁素体的“中脊”和“边脊”，下贝氏体碳化物的析出形态等，研究了贝氏体碳化物的不同特殊析出形态和α／γ相界面的巨型台阶，提出贝氏体铁素体可能按置换型原子体扩散控制台阶机制长大。     

贝氏体相变理论研究工作的主要回顾

贝氏体分上贝氏体和下贝氏体。粒状贝氏体和准贝氏体为贝氏体转变的初级阶段,粒状组织不属于贝氏体。各类组织均有自己的Ｃ曲线。由Ｃ曲线组成中温ＴＴＴ图,能形成几个海湾。贝氏体预相变期发生溶质原子偏聚,贫溶质区邓形核益。贝氏体在溶质原子扩散影响下相变基元沿缺陷面方向切变而增宽（厚）,板条端部区相变基元平均叠加而伸长。贝氏体在晶体学上有切变性质,在热力学上有切变可能。     

38Si2Mn2Mo钢等温下贝氏体的精细结构和晶体学特征

应用透射电镜研究了38Si2Mn2Mo实验用钢320℃等温处理后的下贝氏作组织的晶体学和精细结构．贝氏体含有中脊线、相变单元、残余奥氏体及ε碳化物,贝氏体及奥氏体内存在大量位错．电子衍射和晶体学测量表明下贝氏体惯习面为｛11,7,15｝f型,贝氏体与奥氏体的取向关系为G—T关系．相邻贝氏体板条绕公共面法线＜110＞相对旋转54．7°或60°,形成板条间的不同取向关系,包括近似的｛112｝b孪晶关系．下贝氏体的晶体学位向关系和惯习面分别与板条马氏体的相同或相近,且与由马氏体晶体学表象理论预测的基本一致,说明下贝氏体相交具有马氏体相变的特征．     

含Cu低碳钢CCT曲线及马氏体相变原位观察

利用Linseie L78 RITA淬火/相变热膨胀仪,测定了一种含Cu低碳钢的相变点,绘制了连续冷却转变曲线,结合光学显微镜和显微硬度法分析了冷却速率对相变组织演变规律的影响,利用高温激光共聚焦显微镜对马氏体相变过程进行了原位观察。结果表明:冷却速率为0.5~8℃/s时,随冷却速率的增加,铁素体含量减少,粒状贝氏体(GB)逐渐演变为板条贝氏体(LB),硬度逐渐升高;冷却速率大于15℃/s时,组织全部为板条马氏体。原位观察表明马氏体优先在晶界或晶内位错塞积处形核,新生马氏体在先形核马氏体板条间以一定取向形核长大。     

薄片贝氏体微观组织形貌及其精细结构

利用透射电子显微镜研究了钢中贝氏体转变初期的微观组织形貌及精细结构。首次观察到贝氏体的薄片状形貌及｛１１１｝ｆ面缺陷。贝氏体具有应力应变促发形核特征，｛１１１｝ｆ面缺陷为母相奥氏体的塑性协调亚结构并可作为贝氏体铁素体／奥氏体的相界面。实验结果表明贝氏体初期转变可能具有滑移切变特征。     

钢中马氏体和贝氏体基体组织的特征

板条马氏体和贝氏体组织中板条柬和板条块尺寸的细化对于高强度结构钢的强化和韧化是重要的。在奥氏体晶界形核的贝氏体铁素体的晶体取向（变体）强烈地受制于其形核处即奥氏体晶界的性质,在小过冷度下产生粗大的板条束／板条块。当相变温度降低或碳含量减少时,更多的贝氏体铁素体变体在晶界形成,细化了板条束和板条块尺寸。这是由于形核能力较小的贝氏体铁素体变体更容易以较大的驱动力形成,而且由于塑性协调的抑制,伴随不同贝氏体铁素体变体形成而产生的相变应变的自协调也增加。尽管是类似的变体选择,但含碳量的增加将导致板条马氏体中板条柬／板条块的尺寸减小。这是因为在Ms温度下驱动力随含碳量的变化较小,以及马氏体转变温度比贝氏体的低,能在更大范围内自协调。     

贝氏体巨型台阶和界面结构

使用ＴＥＭ和ＨＲＥＭ分别对贝氏体铁素体和Ｃｕ－Ｚｎ－Ａｌ合金贝氏体台阶形貌和界面结构进行了观察。钢中贝氏体铁素体和Ｃｕ－Ｚｎ－Ａｌ合金贝氏体宽面上存有单台阶、多台阶、系列台阶和三维台阶。贝氏体铁素体台阶高度为６～１６０ｎｍ，相当于｛１１１｝晶面１０００个原子层厚度。Ｃｕ－Ｚｎ－Ａｌ合金台阶高度为几个至几十个纳米。贝氏体铁素体有与马氏体不同的丰富的精细结构。贝氏体铁素体和Ｃｕ－Ｚｎ－Ａｌ合金中有丰富的台阶和巨型台阶。文中讨论了贝氏体的相变机制。     

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.