纳米晶Al88Ce2Ni10铝合金的形成

通过晶化法，可以将快凝Ａｌ８８Ｃｅ２Ｎｉ１０非晶铝合金制备成纳米晶合金。纳米晶合金的组织为αＡｌ固溶体和金属间化合物Ａｌ３Ｎｉ及Ａｌ１１Ｃｅ３组成的多相纳米晶结构。在６０３～７７３Ｋ较宽退火温区内，用Ｓｃｈｅｒｅｒ公式计算各晶化相，得到αＡｌ、Ａｌ３Ｎｉ及Ａｌ１１Ｃｅ３的晶粒尺寸分别为３１～３１６、２２～２０７及１９～１６５ｎｍ。结果表明，通过控制热处理条件，可以获得不同晶粒尺寸的纳米晶合金。其中获得晶粒细小、结构均匀超细纳米晶合金的最佳退火温度为第二ＤＳＣ峰值温度附近     

用机械合金化方法制备Ni-Al系金属间化合物

用球磨机分别对Ｎｉ－５０ａｔ．－％Ａｌ和Ｎｉ－２５ａｔ．－％Ａｌ混合粉末进行机械合金化，并对Ｎｉ_３Ａｌ预合金粉末进行高能球磨，观察了粉末的金相组织，测定了粉末的硬度、平均直径和晶粒尺寸，并作了ＸＲＤ物相分析结果表明，经３ｈ研磨，Ｎｉ－５０ａｔ．－％Ａｌ混合粉末变成ＮｉＡｌ金属间化合物，其晶粒直径约５ｎｍ；经５ｈ机械球磨，Ｎｉ－２５ａｔ．－％Ａｌ混合粉末成为无序的亚稳定Ｎｉ固溶体，而Ｎｉ_３Ａｌ预合金粉末由Ｌｌ_２型长程有序金属间化合物转变为ｆｃｃ无序固溶体；球磨更长时间，则形成纳米晶．     

机械合金化Al－Fe－Ni亚微晶合金的性能及热稳定性

测定了机械合金化（ＭＡ）及热静液挤压工艺制备Ａｌ－４．９Ｆｅ－４．９Ｎｉ合金的室温及高温拉伸性能。采用透射电镜观察了４００～５００℃热处理后合金的微观结构。研究结果表明，合金具有较好的高温强度及热稳定性、合金强度和稳定性的改善是由于细小晶粒，以及弥散分布于基体中的Ａｌ＿３（Ｆｅ，Ｎｉ）导致的强化及对晶粒的稳定化作用。经５００℃×２０ｈ热处理后，Ａｌ＿３（Ｆｅ，Ｎｉ）金属间化合物没有明显的粗化。此外，超细晶粒（约０．１５μｍ）使合金产生加工软化，导致变形不均匀性增加，延伸率减少，经热处理后，晶粒长大，加工软化减弱。     

用机械合金化方法制备Ni—Al系金属间化合物

用球磨机分别对Ｎｉ－５０ａｔ．－％Ａｌ和Ｎｉ－２５ａｔ．－％Ａｌ混合粉末进行机械合金化，并对Ｎｉ３Ａｌ预合金粉末进行高能球磨，观察了粉末的金相组织，测定了粉末的硬度、平均直径和晶粒尺寸，并作了ＸＲＤ物相分析。结果表明，经３ｈ研磨，Ｎｉ－５０ａｔ．－％Ａｌ混合粉末变成ＮｉＡｌ金属间化合物，其晶粒直径约５ｎｍ；经５ｈ机械球磨，Ｎｉ－２５ａｔ．－％Ａｌ混合粉末成为无序的亚稳定Ｎｉ固溶体，而Ｎｉ３Ａｌ预合     

溅射Ni-8Cr-3.5Al纳米晶涂层的抗高温氧化行为

对Ｎｉ－８Ｃｒ－３．５Ａｌ质量分数,％合金及其纳米晶涂层进行了１０００℃空气中高温氧化研究。结果表明：Ｎｉ－８Ｃｒ－３．５Ａｌ纳米晶涂层的抗高温氧化性能优于Ｎｉ－８Ｃｒ－３．５Ａｌ合金。这主要在于Ｎｉ－８Ｃｒ－３．５Ａｌ纳变涂层表面生成了具有分层结构含一连续α－Ａｌ２Ｏ３内层的氧化膜,而Ｎｉ－８Ｃｒ－３．５Ａｌ合金则生成了由Ｃｒ２Ｏ３内氧化物组成的氧化膜。讨论了涂层氧化膜的生成过程。     

热压NiAl纳米晶块体材料的HREM观察及EDS分析

利用高分辨电镜（ＨＲＥＭ）及场发射电镜纳米尺度成分分析技术（ＥＤＳ分析）研究了机械合金化和真空热压技术制备的纳米ＮｉＡｌ块体材料的微观结构。ＨＲＥＭ及ＥＤＳ分析结果表明在球磨过程中形成第二相粒子Ａｌ２Ｏ３分布于ＮｉＡｌ晶粒内部或边界上,分布于晶粒边界上的Ａｌ２Ｏ３对晶界起钉扎作用,有效地抑制晶粒长大;此外,观察到纳米晶粒间存在无序区,这些无序区也是抑制晶粒长大的一个因素。     

纳米晶Cu30Al70合金的形成及其催化活性

本文利用机械球磨的方法将工业上广泛应用的传统的ＲａｎｅｙＣｕ催化剂的前体Ｃｕ３０Ａｌ７０合金制成了纳米晶合金催化材料，并研究了它在木糖加氢反应中的催化活性。结果表明，制成的纳米晶合金ＣｕＡｌ２相的平均晶粒尺寸为１２ｎｍ，球料比和球磨时间极大地影响形成的纳米晶Ｃｕ３０Ａｌ７０合金的晶粒尺寸，纳米晶Ｃｕ３０Ａｌ７０合金组织较均匀，元素分布均匀，活化后的催化剂具有较高的催化活性。     

纳米晶Cu_30Al_70合金的形成及其催化活性

本文利用机械球磨的方法将工业上广泛应用的传统的ＲａｎｅｙＣｕ催化剂的前体Ｃｕ３０Ａｌ７０合金制成了纳米晶合金催化材料，并研究了它在木糖加氢反应中的催化活性．结果表明，制成的纳米晶合金ＣｕＡｌ２相的平均晶粒尺寸为１２ｎｍ，球料比和球磨时间极大地影响形成的纳米晶Ｃｕ３０Ａｌ７０合金的晶粒尺寸，纳米晶Ｃｕ３０Ａｌ７０合金组织较均匀，元素分布均匀，活化后的催化剂具有较高的催化活性．     

高能量密度等离子体微晶化对Ni3Al高温氧化的影响

应用高能量密度等离子体对Ｎｉ３Ａｌ进行微晶化处理，在合金表面获得了晶粒尺寸小于３００ｎｍ的微晶层。对比研究了Ｎｉ３Ａｌ微晶处理前后在氧气中１０００℃高温氧化的行为和规律。发现微晶化处理后的试样氧化膜晶粒被极大地细化，合金中Ａｌ选择氧化得到促进，氧化速率明显降低，氧化动力学服从四次方规律ｘ４＝ｋｐｔ。     

定向凝固Ni3Al合金高温变形行为的研究

定向凝固（ＤＳ）Ｎｉ３Ａｌ合金在１０００至１０５０℃温区，应变速率为２．１×１０（－４）ｓ（－１）时，应变速率敏感指数ｍ大于０．３，最大延伸可达１８５％，具有超塑变形的行为待征．金相及电子显微镜观察表明：超塑变形后，原始柱状晶内有亚结构及新晶粒生成。认为ＤＳＮｉ３Ａｌ高温变形后发生了动态再结晶过程，并由此导致ＤＳＮｉ３Ａｌ合金呈现超塑现象．     

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。