离心熔模精铸TiAl合金与ZrO2型壳的界面反应

选用CaO增强的ZrO2作为TiAl熔模精密铸造用陶瓷型壳的面层材料,通过OM、SEM、EDS和XRD对TiAl合金界面反应处进行形貌分析和元素线扫描分析,研究离心熔模铸造TiAl合金与ZrO2型壳的界面反应.结果表明:在较低的转速(200 r/min)条件下,ZrO2陶瓷与TiAl合金的反应层厚度较小,大约为5 μm;而在较高的转速(400 r/min)情况下,ZrO2陶瓷与TiAl合金的反应层厚度约为20 μm,界面有轻微粘砂.     

γ-TiAl与氧化锆陶瓷模壳的界面反应

采用扫描电镜、电子探针、微区分析、面分布等方法研究了CaO稳定的ZrO2陶瓷型壳与TiAl基合金熔体的界面反应.反应层厚度在80-280μm之间,该区域晶界粗大,电子探针面分析证明是明显的富Zr区.延长金属TiAl与模壳的反应时间,以获得较大的反应界面,进一步研究TiAl熔融液与模壳之间的反应机理.     

Ti-47Al-2Cr-2Nb-xTiB_2合金与Al_2O_3陶瓷型壳界面反应的研究

实验室条件下制备了Ti-47Al-2Cr-2Nb-xTiB2(x=0、0.6%、1.0%,体积分数)合金熔体与Al2O3陶瓷型壳的界面反应层。借助SEM、EDS、XRD以及显微硬度测量等手段,对3种TiAl基合金熔体与Al2O3陶瓷型壳的界面反应情况进行了分析和比较。结果表明,TiAl基合金中加入TiB2,能有效减少TiAl基合金熔体与Al2O3陶瓷型壳的界面反应。TiAl基合金与AlO陶瓷型壳间的界面反应是一种不均衡进行的扩散型化学反应,并建立了界面反应的宏观模型。     

EDXRF法直接测定氧化物陶瓷材料组分

叙述了用能量色散X射线荧光法(EDXRF)同时测定氧化物陶瓷材料组分的分析方法。该方法对样品无损，可直接测定ZrO2 Y2O3，ZrO2 CaO，ZrO2 Y2O3 CaO 3种陶瓷材料中的CaO，Y2O3和ZrO2；该方法快速、简便、可适用于粉末混合料和经高温烧结后的上述3种陶瓷材料；测定各组分的含量范围为：2％-25％的CaO，1．5％-20％的Y2O3，70％-98％的ZrO2，测定CaO和Y2O3的相对标准偏差好于2％，测定ZrO2的相对标准偏差好于1％。     

熔模铸造Ti-1100高温钛合金的界面反应(英文)

研究不同面层材料的Ti-1100高温钛合金界面反应特性。通过对比反应层的厚度,元素分布以及微观硬度研究了面层型壳材料以及型壳预热温度对界面反应的影响。结果表明:采用ZrO2面层材料型壳浇注的Ti-1100铸件反应层的厚度和硬度明显高于采用Y2O3面层材料型壳浇注的合金;型壳预热温度越高,界面反应越剧烈;在相同的型壳面层材料和型壳预热温度条件下,Ti6Al4V合金铸件的界面反应α层比Ti-1100合金铸件界面反应层薄,显微硬度低,表现出较好的稳定性。     

BN基复合型壳熔模精铸钛镍合金时的界面反应

研究了一种新型钛合金精密铸造用型壳--BN基复合型壳在精铸钛镍合金时的界面反应及反应层的形成机制.研究表明,即使在钛镍合金熔液过热较高(浇注温度为1 600℃)的情况下,这种型壳与钛镍合金的反应也较小,铸件表面反应层厚度仅为几个μm.BN基复合型壳,在浇注温度较低的情况下,有望成为Y2O3、ZrO2或钨粉等钛合金熔模精密型壳面层材料的替代品.     

高铌TiAl合金与陶瓷型壳的界面反应

研究了高铌TiAl合金Ti-44Al-8Nb-0.2W-0.1B-0.1Y(at%)分别与Al2O3/ZrO2/Y2O3坩埚的界面反应。测得界面反应层的厚度分别为40,170和20μm。研究中最大的发现在于Ti-44Al-8Nb-0.2W-0.1B-0.1Y(at%)合金在3种坩埚中凝固后显微组织的转变。经测定该合金在3种坩埚中凝固获得的试样中氧含量分别为0.35,0.41和0.11(at%)。由于在合金熔化和凝固过程中,坩埚中的氧元素扩散进入合金基体,较高的氧含量导致合金显微组织发生转变,在与Al2O3和ZrO2坩埚反应的合金中发生了包晶反应。作为对比,选取一种低铌含量的TiAl合金Ti-49.5Al-2Cr-2Nb。经测定在3种坩埚中反应的氧含量分别为0.40,0.63和0.25(at%),但是组织却没有明显的差异。     

Structure Heredity Effect of Mg-10Y Master Alloy in AZ31 Magnesium Alloy

研究了高铌TiAl合金Ti-44Al-8Nb-0.2W-0.1B-0.1Y (at％)分别与Al2O3/ZrO2/Y2O3坩埚的界面反应.测得界面反应层的厚度分别为40,170和20 μm.研究中最大的发现在于Ti-44Al-8Nb-0.2W-0.1B-0.1Y(at％)合金在3种坩埚中凝固后显微组织的转变.经测定该合金在3种坩埚中凝固获得的试样中氧含量分别为0.35,0.41和0.11 (at％).由于在合金熔化和凝固过程中,坩埚中的氧元素扩散进入合金基体,较高的氧含量导致合金显微组织发生转变,在与Al2O3和ZrO2坩埚反应的合金中发生了包晶反应.作为对比,选取一种低铌含量的TiAl合金Ti-49.5Al-2Cr-2Nb.经测定在3种坩埚中反应的氧含量分别为0.40,0.63和0.25 (at％),但是组织却没有明显的差异.     

Ti/ZrO2和TiAl/ZrO2反应的差热分析

借助SEM和差热分析研究Ti-ZrO2（CaO）和TiAl-ZrO2（CaO）体系在不同加热速率时的界面显微组织和反应温度,并利用Kissinger方程对反应动力学参数进行计算。结果表明：随着加热速率的提高,Ti-ZrO2（CaO）和T认1．ZrO2（CaO）体系的化学反应逐渐减弱,初始反应温度逐渐升高;Al元素的加入使Ti和ZrO22（CaO）的初始反应温度提高近170℃,从而弱化Ti与ZrO2（CaO）的界面反应;Ti-ZrO2（CaO）体系和TiAl-ZrO2（CaO）体系反应活化能分别为l348kJ／mol和l675kJ／mol,反应级数分别为1．51和1．59。     

ZrO2-云母复相微晶玻璃的微观组织研究

在以氟金云母KMg3Si3AlO10F2为主晶相的微晶玻璃中，以CaO替换部分K2O，同时再添加适量的ZrO2，可得到ZrO2-云母复相微晶玻璃。用XRD，SEM及EDXS研究了ZrO2的添加对可切削微晶玻璃中云母析晶性能及显微组织的影响。结果表明，ZrO2可以通过影响分相而促进玻璃的析晶；在CaO稳定的作用下，能够析出较多的t-ZrO2;ZrO2的加入能明显抑制云母晶体的长大，由于ZrO2的浓度起伏，析出不同形态的组织结构。     

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.     

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。