La_2O_3-Mo阴极的发射机理

采用热分析、原位ＸＰＳ等方法对 Ｍｏ—Ｌａ２Ｏ３阴极中 Ｌａ的价态进行了研究,探讨了该阴极的发射机理．实验结果表明,在高温下Ｌａ２Ｏ３可以被Ｍｏ２Ｃ还原成单质Ｌａ． Ｌａ２Ｏ３－Ｍｏ阴极的发射可用原子膜机理解释：在阴极工作过程中,还原得到的 Ｌａ覆盖在Ｍｏ基体表面,降低了基体 Ｍｏ的逸出功,促进了阴极的发射根据此机理提出Ｌａ２Ｏ３－Ｍｏ电子管制备和运行工艺．使电子管的工作寿命提高到了满足实际应用要求的水平．     

碳化La2O3—Mo阴极材料的高温XPS研究

采用高温Ｘ射线光电子能谱（ＸＰＳ）对碳化Ｌａ２Ｏ３－Ｍｏ阴极材料表面Ｌａ的价成进行了研究。结果表明,材料中的Ｌａ２Ｏ３可以被Ｍｏ２Ｃ还原成单质Ｌａ。单质Ｌａ的结合能高于Ｌａ２Ｏ３的结合能。从实验上证实单质Ｌａ３ｄ５／２的结合能为８３５．９６ｅＶ,并首次给出单质Ｌａ３ｄ３／２结合能实验数值为８５２．２３ｅＶ。     

La2O3-Mo阴极表面碳化层作用机制研究

用光电子能谱和Ａｕｇｅｒ电子能谱等分析手段对纯钼丝表面离子注Ｌａ后形成的Ｌａ２Ｏ３－Ｍｏ阴极表面碳化层的作用机制进行了研究。实验结果表明,碳化层主要起到产生活性物质Ｌａ的作用,此外还具有贮存和输运活性物质的作用。改变阴极碳化工艺可使Ｌａ２Ｏ３－Ｍｏ三极管阴极的寿命由初期的１４ｈ提高到满足实际应用水平（１０００ｈ）的１４３６．５ｈ。     

Mo—La2O3烧结坯间隙杂质的研究

通过扫描电镜（ＳＥＭ）、电子探针（ＥＰＭＡ）、Ｘ射线衍射（ＸＲＤ）及俄歇电子能谱（ＡＥＳ）研究了Ｍｏ－Ｌａ２Ｏ３烧结坯中的间隙杂质。结果表明：Ｌａ２Ｏ３的加入提高了烧结睛坯的抗弯强度和韧性。间隙杂质不驻存在于Ｍｏ中,而且在Ｌａ２Ｏ３粒子表面吸附,使晶界杂质浓度降低。     

钼酸铵在氢气气氛中的还原行为

通过Ｘ射线衍射（ＸＲＤ）分析，研究了三种多相钼酸铵在高温下的氢还原行为。结果表明，高温下氢气气氛中，钼酸铵首先发生热分解的，生成ＭｏＯ３，再发生还原生成ＭｏＯ２。热分解过程形成（ＮＨ４）２Ｍｏ１４Ｏ４３和（ＮＨ４）２Ｍｏ２２ｏＯ６７中间相，这些中间相在氢气气氛中要较空气气氛中更稳定。ＭｏＯ３在还原过程中形成ＭｏＯ２＼８０和Ｍｏ４Ｏ１１中间相。     

La2O3基导电陶瓷高温电阻率的测试和研究

研究了不同组成的Ｌａ２Ｏ３基导电陶瓷的高温电阻率，结果表明：（Ｌａ２Ｏ３）１－ａ·（Ｘ２Ｏ５）ａ·ＣｕＯ及（Ｌａ２Ｏ３）１－２ａ·（Ｘ２Ｏ５）２ａ·ＣｕＯ具有较低的高温电阻率。由于兼有金属导电机制和半导体导电机制，且两种导电机制随温度变化的作用相反，Ｌａ２Ｏ３基导电陶瓷在室温到１０００℃的温度范围内电阻率变化不大     

EFFECTS OF PRESSURE AND TEMPERATURE ON THE MICROSTRUCTURES OF NANOCRYSTALS α-Fe_2O_3

采用沉淀法制备了α－Ｆｅ２Ｏ３超微粒，在不同的温度和压力下对超微粒粉末进行处理，利用Ｘ射线衍射和Ｍｏｓｓｂａｕｅｒ谱对高压处理前后的样品进行了分析。结果表明，压力主要对微晶的表面或纳米晶体的界面结构产生影响，使晶格畸变或无序程度增加。     

定向凝固Ni_3Al－Mo基合金高温氧化研究

利用热天平连续称重，研究了Ｎｉ３Ａｌ－Ｍｏ基合金（ＩＣ－６）在１２７３，１３７３Ｋ的空气中恒温３００ｈ的氧化行为．用ＥＰＭＡ及ＸＲＤ分析了氧化层的结构和成分，；ＩＣ－６合金的氧化层中包括ＮｉＡｌ２Ｏ４，ＮｉＭｏＯ４，ＭｏＯ２相．氧向内扩散及ＭｏＯ２氧化形成挥发性ＭｏＯ３同时影响着ＩＣ－６合金的氧化进程，氧化反应方程式可表示为：理论方程与实验数据吻合较好．ＭｏＯ３在１２７３、１３７３Ｋ的挥发速率常数分别为３．２７×１０－５和２．５５×１０－４ｍｇ／ｃｍ２·ｓ．     

定向凝固Ni_3Al－Mo基合金高温氧化研究SCIEI

利用热天平连续称重，研究了Ｎｉ３Ａｌ－Ｍｏ基合金（ＩＣ－６）在１２７３，１３７３Ｋ的空气中恒温３００ｈ的氧化行为．用ＥＰＭＡ及ＸＲＤ分析了氧化层的结构和成分，；ＩＣ－６合金的氧化层中包括ＮｉＡｌ２Ｏ４，ＮｉＭｏＯ４，ＭｏＯ２相．氧向内扩散及ＭｏＯ２氧化形成挥发性ＭｏＯ３同时影响着ＩＣ－６合金的氧化进程，氧化反应方程式可表示为：理论方程与实验数据吻合较好．ＭｏＯ３在１２７３、１３７３Ｋ的挥发速率常数分别为３．２７×１０－５和２．５５×１０－４ｍｇ／ｃｍ２·ｓ．     

Ni－La_2O_3复合镀层中的质点弥散与组态研究

用金相、电子探针（ＥＰＭＡ）、透射电镜（ＴＥＭ）及高分辨电子显微镜（ＨＲＥＭ）对Ｎｉ－Ｌａ２Ｏ３复合电镀层的表面形貌及ＬａＯ３质点在镀层中的存在情况进行了研究．发现随着镀液中Ｌａ２Ｏ３颗粒含量增加，复合镀层中Ｌａ２Ｏ３的弥散量增多，镀层晶粒细化．Ｌａ２Ｏ３质点以两种组织状态均匀分布于镍层中：其一为纳米级晶体（绝大多数＜５０ｎｍ）的弥散状态；另一种为微米级（～１μｍ）的“聚合体”状态，是由更微小的纳米晶体（～１０ｎｍ）所组成，由于Ｎｉ－Ｌａ２Ｏ３复合镀层用作扩散渗铝制备Ｌａ２Ｏ３氧化物改性的铝化物涂层的基底层，文中还就复合涂层的Ｌａ２Ｏ３质点弥散与组态对改性的铝化物涂层的显微结构及其氧化行为的影响作了进一步探讨．     

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.     

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.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。