离心成型法制备无宏观界面的Al2O3/Ni功能梯度材料

采用一种新颖的离心成型法制备了无宏观界面的Al2O3/Ni功能梯度材料, 并研究了料浆调制工艺、离心成型制备机理和梯度材料的力学性能。结果表明, 配制料浆时,粘结剂(聚乙二醇)含量为2 mass%、固相含量为63vol.%、球磨时间为36h,可得到流动性良好的料浆,经离心成型（40min,转速3000 r/min）得到无宏观界面的坯体,在1400 C真空烧结2 h,最终得到致密、组元宏观连续过渡的Al2O3/Ni梯度材料。通过调整固相含量和粘结剂含量,可调控Al2O3/Ni复合材料的成分梯度。     

离心成型法制备Al2O3/Ni功能梯度材料及性能表征

用离心成型法制备了Al2O3/Ni功能梯度材料,并研究了料浆调制工艺、制备参数和梯度材料的力学性能.结果表明,良好的料浆的最佳流动性配比为粘结剂(聚乙二醇)含量为2 mass%、固相含量为63 vol.%、球磨时间为36 h.经离心成型-真空烧结(1400℃,2 h)可获得致密、组元宏观连续过渡的Al2O3/Ni梯度材料.该复合材料孔隙率低,力学性能好,抗弯强度可达321 MPa.     

CeO2对渗Si层组织和耐磨性能的影响

采用料浆包渗法,以SiO2粉为Si源,纯Al粉为还原剂,NaF和NH4Cl作为复合活化剂,Al2O3为惰性添加剂,蛋白质(鸡蛋清)为粘结剂,在Cu表面预先镀Ni层随后900℃、12h表面渗Si,制备渗Si层.分别研究了CeO2和Al粉含量对渗Si层组织和摩擦性能的影响.结果表明:当铝粉含量20％时,CeO2含量由3％增加到6％,渗层组织为Ni2Si+ NiSi相;当CeO2含量6％时,铝粉含量由20％增加到30％,渗层组织变化过程:Ni2Si+ NiSi→NiAl→Ni2Al3相,包渗过程由渗硅向渗铝转变;两种渗层的最小摩擦系数都约为纯铜的1/5.     

等离子喷涂Cu-Al2O3梯度涂层与涂层耐磨性分析

利用等离子喷涂法制备了Cu-Al2O3梯度涂层,采用金相显微镜、SEM等手段对涂层进行微观组织结构和磨损后表面形貌分析,用自制销盘式固定磨料磨损试验机,测试了Cu-Al2O3梯度陶瓷涂层的耐磨料磨损性能。结果表明,制备的Cu-Al2O3梯度涂层无明显的组织突变和宏观层间界面,涂层的组织表现出宏观不均匀性和微观连续性分布特征;梯度涂层中当Al2O3含量达到80％时（GC6）,涂层的耐磨性最高,约为基体的3倍,随着Al2O3含量继续增大,纯陶瓷涂层（GC7）的耐磨性有所下降;磨损机制随Al2O3含量增大,由犁沟塑变型转变为脆性断裂、剥落型.     

前处理工艺对Li[Ni1/3Mn1/3Co1/3]O2正极材料结构、形貌和电化学性能的影响（英文）

以[Ni1/3Co1/3Mn1/3]3O4和氢氧化锂为原料,分别采用球磨法和液相法前处理工艺制备层状正极材料Li[Ni1/3Mn1/3Co1/3]O2。采用X？射线衍射（XRD）、场发射扫描电镜（FESEM）、恒流充放电等手段对材料的物理和电化学性能进行表征。结果表明：采用不同前处理工艺制备出的Li[Ni1/3Mn1/3Co1/3]O2材料在结构、形貌和电化学性能上有较大差异;与球磨处理法制备的材料相比,采用液相法前处理工艺制备的Li[Ni1/3Mn1/3Co1/3]O2不但保持了前驱体较好的球形形貌,同时还具有较好的循环稳定性和倍率性能;该样品在20mA/g电流密度下,首次放电容量为178mA·h/g,50次循环后,容量保持率达98.7%;在1000mA/g电流密度下,样品容量为135mA·h/g。     

Al2O3对YSZ电解质材料的制备及性能的影响

文研究了Al2O3掺杂YSZ料浆的流变性质,并采用水基注模凝胶法制备大尺寸薄片材料,对其微观组织进行分析,并对力学性能和电性能进行测试.结果表明,Al2O3的掺入大大降低了YSZ料浆的粘度,改善了YSZ料浆的可浇注性.另外,Al2O3与ZrO2在1600℃烧结不发生固溶反应,主要作为第二相分布在晶界和晶内.少量Al2O3的掺入不仅可以提高YSZ的抗弯强度和断裂韧性,而且可以提高YSZ的电导率.Al2O3含量为1%时,1000℃时电导率达到最大值0.15 S/cm.     

Al2O3基复相陶瓷共沉淀-水热法制备研究

用共沉淀-水热法制备Ni／ZrO2／Al2O3复相陶瓷粉体，并对烧结体的力学性能和显微形貌进行了讨论。复相粉体的表征采用高分辩透射电镜（HRTEM）和X射线衍射（XRD）等技术。结果表明：在1．4．丁二醇介质中300℃水热条件下自生压高压釜中反应12h成功制备了Ni／ZrO2／Al2O3复合陶瓷粉体，并且测得复相陶瓷体积密度和断裂韧性。通过场发射扫描电镜观察得到烧结体中t-ZrO2颗粒和Ni颗粒的平均尺寸。     

反应热压法制备Al2O3/NiCrAl复合材料及功能梯度材料

采用NiO、Al和Cr粉末反应热压制备了Al2O3/NiCrAl复合材料,NiCrAl合金由NiO还原出来的Ni与添加的Cr和Al反应形成.制备了不同Al2O3含量的Al2O3/NiCrAl复合材料,并以Al2O3体积分数分别为25%、52.2%和75%的Al2O3/NiCrAl复合材料为过渡层制备了Y稳定氧化锆(YSZ)到NiCrAl合金的功能梯度材料.X射线衍射分析、金相观察、硬度测量和热循环冲击实验结果表明:用该方法制备的复合材料由Al2O3陶瓷相和(Ni,Cr,Al)固溶体组成,而Al2O3颗粒由NiO与Al原位反应形成,尺寸细小,呈弥散分布.该功能梯度材料经从室温到1 000℃空气中10次热循环后未发现有裂纹,表明该方法制备的材料陶瓷相与合金相有良好的相容性、较高的结合强度、良好的耐高温抗氧化及热循环冲击性能.     

激光快速成形316L不锈钢／镍基合金／Ti6A14V梯度材料

用激光快速成形法制备了致密、无裂纹的316L不锈钢（SS）／镍基合金／Ti6A14V梯度薄壁件．EDS与XRD分析显示,在316LSS／镍基合金梯度过渡区内为单相γ奥氏体,硬度沿316LSS到镍基合金方向逐步增加;在镍基合金／Ti6A14V梯度过渡区内,组织变化顺序为：γ→γ＋β＋TiNi3＋Ti2Ni→TiNi3＋Ti2Ni＋β→α＋β＋Ti2Ni→α＋β;过渡区内,Ti6A14V含量为20％（质量分数）时,硬度达到最大值HV10 830,随后,随Ti6A14V含量增加,硬度逐渐减小．     

FASHS技术制备TiB2+Ni/Ni3Al/405不锈钢梯度材料

采用电场激活自蔓延高温合成(FASHS)技术制备了TiB2 Ni/Ni3Al/405不锈钢梯度材料.试验中首先将镍粉和铝粉球磨处理以促进燃烧反应发生,然后采用FASHS技术利用自蔓延燃烧反应热连接制备了TiB2 Ni/Ni3Al/405不锈钢梯度材料.用SEM和XRD分析了梯度材料各层的界面微观组织及相组成,用洛氏硬度计、显微硬度计及磨料磨损试验机分析了材料的力学性能、硬度及表面抗磨性.结果表明,金属陶瓷复合层、Ni3Al层和405不锈钢金属片间形成了可靠的冶金结合,金属陶瓷复合材料表面硬度为90HRA,材料的化学成分和显微硬度呈梯度分布,耐磨性优于20Cr渗碳钢.     

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).     

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.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.