CuO/Al铝热剂体系绝热温度的计算机数值计算与分析研究

根据绝热温度的热力学计算原理,采用TurboC2程序编制出CuO/Al体系绝热温度的数值计算程序。对体系绝热温度进行了数值计算并进行了验证,同时也对添加不同稀释剂Cu粉对绝热温度的影响进行了研究。结果表明,体系预热温度较低时,绝热温度为产物Cu的沸点温度(2843K),标况下约有52.9%的产物Cu为气相,预热温度仅仅提高了产物Cu的蒸发量。     

原位合成Cu/TiC材料的热力学计算

比较了Cu-Ti-C三元系中各种可能反应的标准吉布斯自由能,同时利用循环试算法计算了Cu-Ti-C反应体系的绝热温度和Cu的熔化率.结果表明:TiC为热力学最稳定产物,制备Cu/TiC在热力学上是可行的;随着Cu含量的增加,反应变得困难,自蔓延燃烧合成法不宜制备低TiC含量的材料;提高预热温度,反应变得容易;反应体系的绝热温度和Cu的熔化率都与预热温度有关.     

Al2O3/Cu复合材料制备中的Cu2O-Al体系化学反应

对Cu2O与Al进行热力学分析后将其粉末压制成块,测试了不同温度下反应的热分析曲线,并对反应后的试样进行X射线衍射分析.结果表明Cu2O-Al体系化学反应包括3个阶段,即第1阶段体系温度T＜910 K,有少量Al2O3和Cu生成;第2阶段体系温度为910 K≤T＜1103 K,Cu2O-Al体系未发生化学反应;第3阶段体系温度为1103 K≤T≤1373 K,Cu2O-Al体系发生化学反应,其产物为Cu、Al2O3及CuAlO2.     

自蔓延冶金法制备硼粉

提出了自蔓延冶金法制备硼粉的新工艺,由计算可知,B2O3-Mg反应体系的绝热温度为2 604 K,大于自蔓延判据温度1 800 K,故采用自蔓延反应是可行的.分析了添加剂MgO和预热温度对反应体系绝热温度的影响,并对B2O3-Mg体系的相关反应热力学数据进行了分析.由DTA分析可知,B2O3-Mg反应体系在1 123～1 203 K时的放热峰表观活化能为903.75 kJ/mol,反应级数为1.由XRD分析确定了燃烧产物以及各个阶段的浸出产物相组成,证实了三步浸出方案的可行性.考察了自蔓延反应初始条件对硼粉纯度的影响,硼粉纯度可达92.43%,平均粒度为0.5～0.8μm.     

PHASE RELATIONSHIPS IN Cu-RICH (Cu+1.0 at.-%Ni)-Al-In and (Cu+1.0at.-%Sn)-Al-In SYSTEMS

本文用X射线衍射分析法研究了(Cu+1.0at.-％Ni)-Al-In和(Cu+1.0at.-％Sn)-Al-In系富铜合金相图的室温截面和500℃等温截面.结果表明,1.0at.-％Ni加入Al-Cu-In系富铜合金时,室温下A1和In在α-Cu中的固溶极限分别为10.8和2.7at.-％;在500℃时为19.0和10.5at.-％,而加入1.0at.-％Sn时,室温下Al和In在α-Cu中的固溶极限为18.7和4.9at.-％;在500℃时则为22.0和11.6at.-％,研究结果表明,少量Ni的添加,可使Al-Cu-In系富铜合金变为可热处理强化合金。     

(Cu+1.0at-％Ni)-Al-ln和(Cu+1.0at-％Sn)-Al-ln系富铜合金的相关系

本文用X射线衍射分析法研究了(Cu+1.0at.-％Ni)-Al-In和(Cu+1.0at.-％Sn)-Al-In系富铜合金相图的室温截面和500℃等温截面.结果表明,1.0at.-％Ni加入Al-Cu-In系富铜合金时,室温下A1和In在α-Cu中的固溶极限分别为10.8和2.7at.-％;在500℃时为19.0和10.5at.-％,而加入1.0at.-％Sn时,室温下Al和In在α-Cu中的固溶极限为18.7和4.9at.-％;在500℃时则为22.0和11.6at.-％,研究结果表明,少量Ni的添加,可使Al-Cu-In系富铜合金变为可热处理强化合金。     

自蔓延高温合成CaB6的基础研究

估算了CaB6的标准生成熔、恒压热容、标准熵值.通过计算CaO-B2O3-Mg反应体系的绝热温度,确定了该体系自蔓延反应进行的可行性.利用自蔓延高温合成的优点,以CaO,B2O3和Mg为原料制备CaB6.对燃烧产物进行X射线衍射分析,从理论上确定了燃烧产物的浸出条件.实验证实了该工艺可行,并得到了理想的CaB6,产品纯度达96.82%.     

工艺参数对SHS法制备TiC-Ni(Mo)金属陶瓷复合材料的影响

为了研究预压坯相对密度、预热温度、反应物配比、孔隙率等工艺参数对TiC-Ni(Mo)铝基金属陶瓷复合材料高温合成过程的影响作用,采用自蔓延燃烧合成(SHS)技术在7A52铝合金表面制备了TiC-Ni(Mo)金属陶瓷复合涂层,利用扫描电镜(SEM)、X射线衍射分析(XRD)对涂层的物相结构进行了分析。结果表明:体系的燃烧速度随预压坯相对密度的提高呈先增后减的趋势,预压坯的最佳相对密度约为55%;体系的燃烧温度随预热温度增长而增长,最佳预热温度区间在400~450K;体系的绝热温度随体系中Ni-Mo含量的提高而降低,最合适的配比方案为TiC-20Ni(Mo)。     

Mo-30Cu合金的组织与性能

采用液相烧结法制备出Mo-30Cu合金,利用XRD,SEM,TEM等对该合金的组织进行分析观察,并研究烧结温度、相对密度对Mo-30Cu合金组织性能的影响.结果表明:该合金组织分布均匀,组织中只含有Mo、Cu两相,在两相之间有一Mo、Cu互溶区;烧结温度是影响Mo-30Cu性能的最重要因素,在1300℃烧结的合金相对密度为99.6%,热导率为196 W·(m·K)-1.     

钨/铜第一壁复合材料界面行为研究

通过等离子喷涂技术在铜合金基体上制备具有不同适配层的钨涂层第一壁复合材料,并对其界面行为进行研究.结果表明,Wu/Cu、NiCrAl和Ti适配层均能明显降低W/Cu界面热应力,但其界面仍是第一壁复合材料最可能失效的位置;W/Cu适配层能有效提高此复合材料界面的结合强度,增幅高达30%.     

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.