渗铝NiAl—20?金属间合金的高温热腐蚀

本文研究了在９５０℃空气中，表面涂Ｎａ２ＳＯ４盐膜的条件下，ＮｉＡｌ，ＮｉａＬ－２０％Ｆｅ及渗铝后的高温热腐蚀行为。在热腐蚀过程中，ＮｉＡｌ合金表面形成ＡｌＯ３膜，显示出一定的耐蚀性能。但Ａｌ２Ｏ３膜易开裂，Ａｌ２Ｏ３膜易开裂，Ａｌ２Ｏ３膜的溶解开裂会引发合工发生快速热腐蚀，２０％Ｆｅ的加入则使ＮｉＡｌ合金的耐蚀性能显著变差，合金表面不能形成单一的Ａｌ２Ｏ３膜；渗铝处理可以明显提高ＮｉＡｌ－２０＾     

Na_2SO_4 INDUCED HOT CORROSION OF Ni_3Al－Fe INTERMETALLIC COMPOUND AT INTERMEDIATE TEMPERATURES

研究了Ｎａ_２ＳＯ_４沉积盐引起的Ｎｉ_３Ａｌ－Ｆｅ于７００一８２０℃空气中的腐蚀行为。结果表明，Ｎｉ_３Ａｌ－Ｆｅ遭受自持性的热腐蚀。热腐蚀的发生似可归因于Ｆｅ与Ｎａ_２ＳＯ_４反应的产物Ｎａ_２Ｏ与Ｎａ_２ＳＯ_４形成了Ｎａ_２Ｏ－Ｎａ_２ＳＯ_４共晶熔融盐，随后合金中Ｍｏ的氧化产物ＭｏＯ_３参与电化学阴极还原反应，从而引发合金快速的热腐蚀。此外，熔盐中Ｎａ_２ＳＯ_４与ＭｏＯ_３反应生成的ＳＯ_３导致了熔盐的高酸度和合金的内硫化，从而进一步加剧了腐蚀的进程。     

NiAl微晶涂层对NiAl-TiC复合材料高温氧化性能的影响

研究了磁控溅射ＮｉＡｌ微晶涂层对ＮｉＡｌ－ＴｉＣ（２０％,体积分数）复合材料１０００－１１００℃高温氧化性能的影响。结果表明,ＮｉＡｌ微晶涂层大大提高了ＮｉＡｌ－ＴｉＣ复合材料的恒温及循环氧化性能,降低氧化速率几个数量级,对于ＮｉＡｌ－ＴｉＣ复合材料来说,其表面形成以ＴｉＯ２为主的复合氧化物,而施加ＮｉＡｌ微晶涂层后,其表面氧化物主要是Ａｌ２Ｏ３。     

Fe—Mn─Al合金的腐蚀性能与钝化膜的研究

应用阳极极化及ＡＥＳ／ＸＰＳ技术,研究了Ｆｅ－３０．８Ｍｎ－８．２Ａｌ奥氏体合金在ｐＨ值为－０．８至１５．３的水溶液中的腐蚀性能,并与Ｆｅ－３０Ｍｎ合金、低碳钢、９％Ｎｉ低温钢及１Ｃｒ１３不锈钢进行对比。在所测试的水溶液中,该合金的腐蚀抗力优于低碳钢和Ｆｅ－３０Ｍｎ合金,与９％Ｎｉ钢相当,但不及１Ｃｒ１３不锈钢。Ｆｅ－３０．８Ｍｎ－８．２Ａｌ合金在１ｍｏｌ／ＬＮａ２ＳＯ个中形成的钝化膜的最表层可能为氢氧化物,而膜的主体由Ｆｅ２Ｏ３、Ｍｎ２Ｏ３及Ａｌ２Ｏ３组成。     

渗铝涂层对Ni3Al—Mo基合金高温氧化的防护作用及机理

采用高活度渗铝工艺在ＩＣ－６（Ｎｉ３Ａｌ－Ｍｏ基）合金表面获得内扩散型渗铝涂层，在氩气环境下对渗铝涂层进行扩散处理。利用光学显微镜、ＳＥＭ、ＥＰＭＡ、ＸＲＤ分析研究了涂层的成分及组织结构，测定表明，涂层中的钼以Ｍｏ３Ａｌ沉淀相的形式存在。等温氧化及循环氧化实验表明，渗铝涂层的抗高温氧化性能明显优于ＩＣ－６合金；保护性的Ａｌ２Ｏ３氧化膜阻止了钼的氧化物的形成，避免了ＩＣ－６合金在循环氧化中出现的Ｎｉ     

Pd—Ni—Al涂层的循环氧化和在Na2SO4熔盐中的热腐蚀行为

研究了底温高活性（ＨＴＨＡ）Ｐｄ－Ｎｉ－Ａｌ涂层在１０５０℃人的循环氧化和Ｎａ２ＡＳＯ４熔盐中的热腐蚀结果表明,Ｐｄ－Ｎｉ－Ａｌ涂层表面生成一层致密的氧化膜,抗热腐蚀性能接近Ｐｔ－Ａｌ涂层,优于单渗铝涂层,初步分析了Ｐｄ－Ｎｉ－Ａｌ涂层的高温腐蚀机理。     

渗铝涂层对Ni_3Al－Mo基合金高温氧化的防护作用及机理

采用高活度渗铝工艺在ＩＣ－６（Ｎｉ３Ａｌ－Ｍｏ基）合金表面获得内扩散型渗铝涂层，在氮气环境下对渗铝涂层进行扩散处理．利用光学显微镜、ＳＥＭ、ＥＰＭＡ、ＸＲＤ分析研究了涂层的成分及组织结构，测定表明，涂层中的钼以Ｍｏ３Ａｌ沉淀相的形式存在．等温氧化及循环氧化实验表明，渗铝涂层的抗高温氧化性能明显优于ＩＣ－６合金；保护性的Ａｌ２Ｏ３氧化膜阻止了钼的氧化物的形成，避免了ＩＣ－６合金在循环氧化中出现的ＮｉＭｏＯ４相的多晶型转变，显著改变了合金的抗循环氧化能力；涂层经１０００℃、３００ｈ等温氧化及１０００℃、１００ｈ循环氧化后，未出现β－ＮｉＡｌ相的分解，可认为涂层具有较强的保护作用。     

离子注Mg的β－NiAl涂层的氧化行为

表面扩散渗铝形成的β－ＮｉＡｌ涂层表面注入Ｍｇ＋１×１０１７／ｃｍ２后，在１０００℃空气中恒温氧化２５ｈ，涂层的氧化增重速率有所增加，这是由于注Ｍｇ的β—ＮｉＡｌ涂层表面形成了Ａｌ２Ｏ３氧化物“瘤”，长时间氧化后氧化物“瘤”周围及“瘤”本身发生开裂，引起涂层内氧化。     

两相NiAl—Fe金属间化合物的高温氧化行为研究

研究了ＮｉＡｌ、ＮｉＡｌ－２０Ｆｅ、ＮｉＡｌ－３０Ｆｅ金属间化合物在１０００℃￣１１００℃空气中的氧化行为。ＮｉＡｌ和ＮｉＡｌ－２０Ｆｅ显示较好的抗氧化性能,ＮｉＡｌ－３０Ｆｅ的抗氧化性能却很差。从合金相组成探讨了ＮｉＡｌ－Ｆｅ合金的氧化机制。     

Na2SO4沉积盐引起的Ni3Al—Fe的中温区热腐蚀

研究了Ｎａ２ＳＯ４沉积盐引起的Ｎｉ３Ａｌ－Ｆｅ于７００－８２０℃空气中的腐行为，结果表明，Ｎｉ３Ａｌ－Ｆｅ遭受自持性的热腐蚀，热腐蚀的发生似可归因于Ｆｅ与Ｎａ２ＳＯ４反应的产物Ｎａ２Ｏ与Ｎａ２ＳＯ４形成了Ｎａ２Ｏ－Ｎａ２ＳＯ４共晶熔融盐，随中金中Ｍｏ的氧化产物ＭｏＯ３参与电化学阴极还原反应，从而引发合金快速的热腐蚀，此外，熔盐中Ｎａ２ＳＯ４与ＭｏＯ３反应生成的ＳＯ３导致了熔盐的高酸度和合金的内硫化     

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。