镍镀层内应力及镍镀层中的位错

分析了镀镍工艺操作条件与镍镀层内应力的关系,用透射电子显微镜对镍镀层微观结构进行了观察。结果表明:镍镀层中存在大量位错。是产生镀层内应力的原因之一。     

不同镀层重量的铝硅镀层加热时的镀层结构转变规律

采用扫描电镜和能谱分析仪研究了不同镀层重量的铝硅镀层热成形钢经不同温度和时间加热后的镀层结构转变规律。结果表明,不同重量的铝硅镀层在完全合金化后的镀层结构相同,由基体至表面依次为扩散层、Fe-Al层、Fe-Al-Si层和Fe-Al表面层;随着加热的进行,Fe-Al-Si层和扩散层逐渐增厚,Fe-Al-Si层中Si含量逐渐降低,厚镀层AS150未出现镀层层数减少的现象,薄镀层AS40、AS80出现镀层层数减少的情况。综合考虑铝硅镀层热成形钢加热后的镀层结构、性能变化和产品使用要求,对于1.4 mm厚22MnB5钢基板,薄镀层AS40、AS80的优选热处理工艺为900~930 ℃×3~6 min,厚镀层AS150的优选热处理工艺为900~930 ℃×4~6 min。     

热成形钢镀层研究进展

汽车用热压成形钢镀层成为近年来的研究热点之一。本文概述了正在研究的Al-Si镀层、锌基镀层、Zn-Ni合金镀层及其它镀层。重点对Al-Si镀层和锌基镀层进行了评述,比较了这些镀层的优缺点,并总结了一些改进方法和思路。     

热镀锌合金化镀层粗糙度对镀层抗粉化性能的影响

用SEM和XRD观察和分析了铝含量和合金化时间不同的热镀锌合金化(GA)镀层的表面形貌和组织,用双杯突测量了GA镀层的抗粉化量。结果表明,锌液中铝含量小于0.16 mass%的热镀锌镀层合金化时,镀层表面的Ra值小于1.0μm,且镀层的粉化量小于30 mg/m2,满足汽车板的表面质量要求;此后随着锌液中铝含量的增加,GA镀层的粉化量迅速增加,说明GA镀层的抗粉化性能除与镀层中的铁含量有关外,还与镀层表面的粗糙度有关。锌液中铝含量为0.22 mass%热镀锌镀层合金化时,由于Fe2Al5Znx抑制层的抑制作用,镀层中的δ1k-相出现局部增多的现象,从而恶化了GA镀层的抗粉化性能。     

功能性镀层

具有某种特性的物理机械性能的膜层,如镀硬铬、镍-碳硅耐磨涂层,锡-钴合金银-锡合金的减磨镀层,镀黑镍或镀黑铬的反光镀层,镀银、金、金钴合金的导电镀层,导磁镀层等.离子镀的发展为镀复特殊     

Ni-P镀层研究现状及发展趋势

综述了近十几年来Ni-P镀层研究成果.文中从基材选择、镀液成分、镀层组织结构与性能、热处理对镀层的影响,耐蚀机理、反应机理等方面较全面地反映了 Ni-P镀层研究进展.并对最近几年来发展的三元复合镀作了介绍,指出了Ni-P镀层研究的发展方向.     

Ni-P化学镀层及其复合镀层结合强度的声发射研究

采用四点弯曲-声发射方法，对随热处理温度变化的Ni—P（Re）化学镀层及其复合镀层的失效形式（内聚失效、镀层脱粘）、启裂载荷和启裂挠度进行了检测。结果表明，稀土在镀层与底材界面和粒子界面的平衡偏聚，提高了界面强度、启裂栽荷、启裂挠度和裂纹扩展抗力。400℃以上热处理显著提高了镀层与底材之间界面的结合强度，从而使镀层由镀态时的界面启裂转变为镀层表面的内聚启裂。     

镀层新材料

七十年代初期,首次讨论了利用PVD镀层来减少硬质合金和正具钢磨损的可能性,而碳化钛镀层明显地受到人们的青睐,比如说在R.Bunshah的著作中就是如此。其原因是碳化钛事实上是当时用于CVD的唯一材料,因为人们认为镀层越硬对减少磨损越有效。这项研究成果被日本和列支敦士登工业界相继采用,但是和氮化钛相比,显然由于碳化钛镀层中含有氢和过剩的碳,使其变得特别脆和非常难以制造而很快被放弃,此外,碳化钛是铁灰色的,而氮化钛是     

高耐蚀性非晶态镀层钢板

日本住友金属工业公司研制成功一种新型设备，可用来生产高耐蚀性非晶态镀层钢板。该设备采用熔融盐电解法生产出具有与不锈钢同等耐蚀性的非晶态钢—锰合金镀层钢板。该公司进行了各种镀层研究，掌握了可在２００℃的条件下进行铝—锰合金镀层技术，并制成了连续镀层设备。高耐蚀性非晶态镀层钢板@李兵     

硫酸盐电镀三价铬镀层性能研究

为对硫酸盐体系三价铬镀层性能进行更深入的了解,分析了电镀时间对镀层厚度、表面形貌和镀层耐蚀性的影响.采用X射线荧光光谱仪、体视显微系统对镀层厚度和形貌进行了测试;通过CASS试验、Tafel曲线和EIS曲线测试,对采用不同电镀时间制备的三价铬镀层及六价铬镀层的耐蚀性进行了分析.试验结果显示:三价铬镀层厚度基本随电镀时间的增加而线性增加;电镀时间达到10min时,镀层表面形貌由微孔变为微裂纹状,镀层耐蚀性最好;硫酸盐体系三价铬镀层的耐蚀性与六价铬镀层的耐蚀性相当.可见,硫酸盐体系三价铬镀层具有优良的耐蚀性.     

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.     

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.