Structure and Properties of Titanium Aluminum Alloy Produced by Friction Stir Welding

Russian Physics Journal - The paper deals with the fabrication of lap joints of titanium ОТ4-1 alloy and aluminum AlMg5 alloy sheets by means of friction stir welding (FSW). The X-ray...     

Recent Advances in Friction Stir Welding/Processing of Aluminum Alloys: Microstructural Evolution and Mechanical Properties

Friction stir welding (FSW), a highly efficient solid-state joining technique, has been termed as “green” technology due to its energy efficiency and environment friendliness. It is an enabling technology for joining metallic materials, in particular lightweight high-strength aluminum and magnesium alloys which were classified as unweldable by traditional fusion welding. It is thus considered to be the most significant development in the area of material joining over the past two decades. Friction stir processing (FSP) was later developed based on the basic principles of FSW. FSP has been proven to be an effective and versatile metal-working technique for modifying and fabricating metallic materials. FSW/FSP of aluminum alloys has prompted considerable scientific and technological interest since it has a potential for revolutionizing the manufacturing process in the aerospace, defense, marine, automotive, and railway industries. To promote widespread applications of FSW/FSP technology and ensure the structural integrity, safety and durability of the FSW/FSP components, it is essential to optimize the process parameters, and to evaluate thoroughly the microstructural changes and mechanical properties of the welded/processed samples. This review article is thus aimed at summarizing recent advances in the microstructural evolution and mechanical properties of FSW/FSP aluminum alloys. Particular attention is paid to recrystallization mechanism, grain boundary characteristics, phase transformation, texture evolution, characteristic microstructures, and the effect of these factors on the hardness, tensile and fatigue properties as well as superplastic behavior of FSW/FSP aluminum alloys.     

强激光冲击铝合金改性处理研究

利用新型聚偏1.1-二氟乙烯（PVDF）压电传感器,实现了对激光引发的冲击波压力的实时测量,得到激光引发的冲击波峰压在铝中成指数型的衰减规律;观测了不同约束层材料在铝靶表面产生的激光冲击波,研究了不同约束层对冲击效果的影响;最后用激光冲击强化装置对7050-T7451航空铝合金结构材料进行了冲击强化处理,对试件激光冲击区存在的残余压应力及位错密度进行了测量。结果显示经激光冲击处理的试件表面具有极高的残余压应力,可达-200MPa以上。激光冲击处理后铝合金的位错密度得到显著的提高,疲劳寿命提高到175％～428％。这些重要结果对激光冲击改性处理技术的实际应用具有指导性作用。     

Wear and Coefficient of Friction of a Supermodified Hypereutectic Aluminum–Silicon Alloy

Technical Physics - The friction coefficient and the wear of a hypereutectic aluminum alloy with 15 wt % silicon and a supermodified eutectic structure without primary silicon crystals, obtained by...     

Features of the Radiation-Stimulated Hydrogenation of an Aluminum Surface

By the methods of reflection-absorption IR (infrared) spectroscopy, electrical measurement and AFM microscopy, the process of the radiation-stimulated hydrogenation of the aluminum surface in the Al/ads n-hexane system under γ-irradiation at room temperate is studied. On the basis of the dose dependence of the Al surface specific resistance, two stages of the hydrogenation process in the absorbed dose range (0.5?120 kGy) are revealed. It is established that the transition from the first to the second stage is accompanied by a decrease in the electrical conductivity of Al by 35 times and an increase in the hydride-nanolayer thickness by an order of magnitude. AFM studies of the aluminum surface relief showed that radiation-stimulated hydrogenation is accompanied by the formation of carbon-nanotube structures. A possible mechanism for the radiation-stimulated hydrogenation of aluminum is suggested.     

Complex Electron-Ion-Plasma Processing of Aluminum Surface in a Single Vacuum Cycle

Russian Physics Journal - The principle of operation and major characteristics of a laboratory setup designed for electron-ion-plasma surface modification of materials and parts in a single vacuum...     

The Extended Surface as a Factor Forming Distinctive Features of Nanodimensional Media

As a result of studying thin-film nano-sized media, it is shown that the extended surface exerts a substantial influence on their distinctive properties. It has been established that, by using special methods to obtain nano-sized media under certain conditions, it is possible to form crystal structures with a high concentration of defects of a prescribed type in the near-surface layers of nanocrystals. The correlations found between the conducting and optical properties of thin-film nano-sized structures are an additional factor that extends the capabilities of controlling their characteristics with a view toward developing miniature effective radiation sources, elements of modulation of laser radiation, dosimeters, and components of thin-film solar cells. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 287–291, May–June, 2005.     

The Surface Structure of a TiNi-Based Powder Alloy Manufactured by the Method of Diffusion Sintering

Russian Physics Journal - The structural features of the surface of a TiNi-based powder alloy produced by diffusion sintering are studied. Two-dimensional porous samples based on a TiNi powder...     

微弧氧化材料表面陶瓷化机理的探讨

根据大量的实验结果总结了微弧氧化过程中的一些规律.并对铝合金微弧氧化表面陶瓷氧化层形成的机理进行了探讨． With micro arc oxidation, a ceramic oxidizing layer with the fare thickness and the high density is formed on aluminum alloys. In the work, the formation mechanism of surface ceramics on aluminum alloys with micro arc oxidation are suggested, based on the experimental data.     

Structural Transformation of the Surface of an Aluminum Alloy after Hydroabrasive Action

The results of investigating an Al–Mg alloy (5.8–6.8 wt % Mg) subjected to hydroabrasive action are presented. It is revealed that the cut surface is contaminated with fragments of particles of the abrasive. The cut-surface relief is studied with the help of scanning electron microscopy. The cut-surface microhardness and the cold-hardened layer depth are determined. The structural transformation near the surface is investigated via X-ray diffraction analysis and transmission electron microscopy. The structural state of the alloy near the surface is demonstrated to be extremely inhomogeneous. Plastic deformation leads to the formation of an ultrafine-grained structure with a heightened level of stresses.     

Features of Structural Phase Transitions of Aluminum Hydroxides under Laser Processing

The results of the studies of laser processing of alkoxide aluminum hydroxides with micrometer and nanometer particle sizes are presented. It is shown that the pseudo-boehmite processing process and phase composition of formed oxides are controlled by particle packing, laser radiation propagation in powder, and specific energy deposition. The main phases formed upon laser heating are γ, α-Al₂O₃; the content of δ, θ-Al₂O₃ is low. The minimum corundum crystallite size is ～50 nm.     

Effect of Ultrafine-Grained Structure of a Material on the Strength Characteristics of an Aluminum Alloy upon Impact Loads

Physics of the Solid State - An increase in the velocities of automobile and aerospace transport and, simultaneously, the necessary of decreasing their masses increase the requirements to the...     

冷轧CC5052铝合金板表层至中心层织构变化的X射线衍射分析

为了对铝合金板轧制技术发展提供依据,采用X射线衍射仪测试极图并使用专用软件计算织构的ODF,研究了热轧后经过454℃×4h预先再结晶退火处理的5052双履带连续冷却铸造铝合金板,进行不同变形量冷轧后自表层至心部层的织构分布状况。冷轧制后变形量小于40%的试样,存在织构强度由表层向中心层提高的变化梯度。变形量大于56.1%的试样,β织构的增加主要是来自剩余位向转变量随变形量的增加;主要织构β较强、Goss和剩余位向较弱,各层之间的织构状态接近。     

A Review of Recent Progress in Solid State Fabrication of Composites and Functionally Graded Systems Via Friction Stir Processing

Friction stir processing (FSP) is a rapidly emerging newer solid-state technique for composite fabrication. It involves surface modification which in turn enables successful adaptation of surface properties through plastic deformations in solid state. During initial years of FSP inception, it was primarily employed in development of metal matrix composites of light metal alloys like aluminum. However, recently, it has gained an alluring role in fabrication of composites of various nonferrous and ferrous metal alloys as well as of polymers. In addition to composite fabrication, FSP has evolved as a revolutionary technique in developing functionally graded systems/surfaces (FGS) of metal matrix. This article covers all aspects of FSP in which reinforcement particles are embedded in the base matrix to develop composites and FGS. It presents a critical review on domains of recent developments, effects of different types of reinforcement particles and properties enhancement of composites, and FGS fabrication. In addition to this, various issues, challenges, and future work that demand attention are systematically addressed.     

ICP-AES测定铜-锌合金中锌及杂质元素砷、铅、锑和铋

采用ICP-AES同时测定铜-锌合金中锌、砷、铅、锑和铋含量,优化了样品溶样条件.方法检出限为0.0003%-0.0012%,回收率为86%-112%,RSD为0.30%-5.17%,测试结果表明,该方法是测定铜锌合金的简单准确快速的方法.     

Inelasticity and Nanostructured Dislocation Deformation of Aluminum–Silicon Alloy with a Supermodified Eutectic Structure

Technical Physics - Young’s modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well as the subgrain size and residual stresses in the strontium modified alloy...