Ti—B4C反应路径分析

通过热力学计算,结合Ｔｉ－Ｂ－Ｃ的等温截面图分别获得了Ｔｉ,Ｂ和Ｃ在１６００℃的化学势稳定图,在满足热力学和质量守恒条件下利用化学势从高向低扩散的原理,预测了在１６００℃等温等压时Ｔｉ和Ｂ４Ｃ之间发生化学反应时可能存在的反应路径,利用扩散偶实验证实了该温度条件下的反应扩散路径为：Ｔｉ／ＴｉＣｘ／ＴｉＢ／Ｂ４Ｃ。     

Cu—Zr基体中Al—Ti—B2O3体系的反应热力学研究

为研究ＴｉＢ２／ＣｕＺｒ 复合材料的增强相在ＣｕＺｒ 基体中形成的热力学条件, 采用ＤＴＡ 分析和不同温度下的热爆试验, 研究了ＡｌＴｉＢ２Ｏ３ 体系的反应热力学行为, 并讨论了其反应合成机制。结果表明： 在１１００℃下, 该体系能自动发生反应, 生成产物为ＴｉＢ２ 和少量Ａｌ２Ｏ３ ; 在较低温度反应时, 产物中存在硼化物过渡相。基于热爆工艺参数, 在ＣｕＺｒ 熔体中制备了ＴｉＢ２／ＣｕＺｒ 复合材料。     

热压过程中MoSi2与B4C的反应研究

本文研究了在热压过程中ＭｏＳｉ２与Ｂ４Ｃ的反应,结果表明,在１６００℃时,ＭｏＳｉ２与Ｂ４Ｃ发生反应,当Ｂ４Ｃ添加量为５％（质量分数）时,室温下存在四种相,Ｍｏ２Ｂ５,ＭｏＳｉ２,ＳｉＣ,Ｓｉ,其反应生成物可以通过Ｍｏ－Ｓｉ－Ｂ相图来推断。     

Al-Ti-C系中TiC形成的热力学与动力学研究

研究了在用熔体反应法制备Ａｌ－Ｔｉ－Ｃ中间合金过程中ＴｉＣ形成的热力学与动力学,实验结果表明：在８５０℃的Ａｌ熔体中,石墨颗粒周围的Ｋ２ＴｉＦ６与Ａｌ发生剧烈的化学反应放出大量的热,在熔体中形成大量的局部高温微区。在这些高温微区内,熔体中的Ｔｉ或ＴｉＡｌ３达到了与Ｃ形成ＴｉＣ的热力学条件,从而在石墨颗粒周围生成大量ＴｉＣ粒子,根据熔体化学反应的热力学条件,提出了８５０℃下在Ａｌ－Ｔｉ－Ｃ中间合金中     

STUDY ON α/γ PHASE EQUILIBRIUM IN Ti-Al-Cr-Fe QUARTERNARY SYSTEM

设计了一种简单的扩散偶,用扩散偶－电子探针法,测定了１２００和１２５０℃Ｔｉ－Ａｌ－Ｃｅ－Ｆｅ四元系中Ｘｃｒ≤４％和ＸＦｅ≤１％范围内的α／γ相平衡关系和相平衡成分,绘出了四元系的局部等温正方形,结果表明,在Ｔｉ－Ａｌ－Ｃｒ－Ｆｅ四元系中,Ｃｒ有提高Ｆｅ在α相中的溶解度的作用,Ｆｅ亦有提高Ｃｒ在α相中的溶解度的趋势。     

Cu-Ni-Ti合金钎料对Si_3N_4陶瓷的润湿与连接

采用座滴法研究了Ｃ４－Ｎｉ－（２７—５６）Ｔｉ合金（原子分数,％,下刚在Ｓｉ３Ｎ４陶瓷上的润湿行为选用真空熔炼合金Ｃｕ３８Ｎｉ３０Ｔｉ３２和Ｃｕ３４Ｎｉ２７Ｔｉ３９作为钎料时,获得的Ｓｉ３Ｎ／Ｓｉ３Ｎ４接头的强度不理想在降低钎料含Ｔｉ量的同时适当降低含Ｎｉ量,重新设计了两种Ｃｕ－Ｎｉ－Ｔｉ（Ｓｉ,Ｂ）合金钎料,并采用膏状形式改善针料成分的均匀性,在１３５３Ｋ,１０ｍｉｎ的针焊条件下获得的Ｓｉ３Ｎ４／Ｓｉ３Ｎ４接头最高三点弯曲强度分别提高至３３８．８和２０６９ＭＰａ,并对Ｓｉ３Ｎ４／Ｓｉ３Ｎ。接头的界面反应进行了分析     

铸钛叶轮气孔,缩孔缺陷的消除

应用多元扩散偶－电子探针微区成分分析技术，研究了Ｔｉ－Ｎｉ－Ｎｂ三元系相图８００℃下的相平衡关系，确定了该三元系相图８００℃等温截面的１２个单相区，２２个两相区和９个三相区。首次给出了Ｔｉ－Ｎｉ－Ｎｂ三元系相图的８００℃等温截面，此外，还确定了４种三元化合物的存在，其中ＸＢ为作者首次发现，其化学计量式为Ｔｉ３Ｎｉ９Ｎｂ８。     

原位合成TiB和TiC增强钛基复合材料热力学

根据热力学理论编程计算了钛与Ｂ４Ｃ反应的反应生成焓ΔＨ与Ｇｉｂｂｓ自由能ΔＧ以及反应式（ｘ＋５）Ｔｉ＋Ｂ４Ｃ＝ｘＴｉ＋４ＴｉＢ＋ＴｉＣ的绝热温度。计算结果表明：钛与Ｂ４Ｃ反应释放出大量热,反应能自发维持,而过量钛与Ｂ４Ｃ反应更易生成ＴｉＢ和ＴｉＣ增强体。由于钛作为稀释剂吸收热量,随着过剩钛含量的增加,反应的绝热温度逐渐下降,过剩钛完全熔解的初始温度逐渐升高。     

活性元素Ti在Ni基钎焊合金／Si3N4界面上动态行为研究

通过润湿性试验研究了Ｎｉ－Ｔｉ合金及（ＢＮｉ－２＋Ｔｉ）合金中Ｔｉ在Ｓｉ３Ｎ４表面的动态行为。利用ＥＰＭＡ和Ｘ－Ｒａｙ技术,分析了Ｎｉ基钎焊合金与Ｓｉ３Ｎ４陶瓷间界面元素分布像及界面相产物。高温Ｎｉ基钎焊合金中Ｔｉ与Ｎｉ的亲合力很强,使合金中Ｔｉ难于向Ｓｉ３Ｎ４侧偏聚而失去活性。热力学计算表明合金中Ｔｉ与Ｓｉ３Ｎ４的界面反应不仅与反应吉布氏自由能△Ｇ有关,也与Ｔｉ在合金中扩散激活能及Ｓｉ３Ｎ４的分解能有关。     

Ti—Ni—Nb三元系相图700℃等温截面

应用多元扩散偶－电子探针微区成分分析技术，测定了Ｔｉ－Ｎｉ－Ｎｂ三元系相图７００℃等温截面，确定了该三元系相图的７００℃等温截面的１２个单相区，２３个两相区和１０个三相区。１２个单相区是：α－Ｔｉ、β－（Ｔｉ，Ｎｂ）、Ｔｉ２Ｎｉ、ＴｉＮｉ、ＴｉＮｉ３、（Ｎｉ）、Ｎｉ３Ｎｂ、Ｎｉ６Ｎｂ７、ＸＡ、ＸＢ、ＸＣ和ＸＤ，其中ＸＢ化合物为首次发现。     

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。