Recent developments in high temperature intermetallics research in China

A comprehensive survey was made of various advances of intermetallics research in China. The investigation focussed on the fundamental research and materials development. Charge density distribution and site occupancy of alloying elements, environmental embrittlement and chemical reaction, interface structures and phase transformation at the atomic scale, nanocrystalline intermetallics and its thermal stability, superplastic behavior and anomalous yield strength peak are reviewed. Several Ti–Al and Ni–Al based alloys have been manufactured, and show good mechanical properties. Diverse components have been fabricated successfully.     

Recent developments in the research of shape memory alloys

Most of shape memory alloys are functional intermetallics. They are now practically being used for couplings, actuators, medical guide wires etc., and are hopeful candidates for smart materials, which already exist. In the present paper, recent developments within nearly 10 years on shape memory alloys and martensitic: transformations, on which shape memory effect and superelasticity are based, were concisely reviewed. Since Ti–Ni alloys are the best practical shape memory alloys, we mostly discussed on the alloys, but we discussed more general problems as well. Furthermore, we discussed the ductility and density of point defects in intermetallics, since they are important problems in intermetallics in general. At the end we introduced some recent applications of shape memory alloys briefly.     

Recent developments in ceramic nanocomposites

Ceramic nanocomposites are drawing considerable interest as processing methods are developed to enable these materials to go from the research laboratory scale to the commercial level. The potential benefits of ceramic nanocomposites can be substantial, but further research is needed. In-depth characterization is also needed in order to understand the novel physical and mechanical properties of these materials. In the literature dealing with mechanical properties, there are still many controversies to be resolved. S. Bhaduri earned her M.S. in metallurgical engineering at the University of Idaho in 1995. She is currently a doctoral candidate at the University of Idaho. S.B. Bhaduri earned his Ph.D. in materials science and engineering at the University of New York at Stony Brook in 1981. He is currently an associate professor at the University of Idaho. Dr. Bhaduri is also a member of TMS.     

Recent development of calcium phosphate-based coatings on titanium alloy implants

Titanium alloy implants are widely employed in biomedical devices and components, especially as hard tissue replacements as well as orthopaedic applications, owing to their favourable properties such as high-strength to weight ratio, low density, low Young’s modulus and biocompatibility. However, metallic implants cannot meet all of the clinical requirements. Therefore, in order to increase their clinical success and long term stability in the physiological environment, surface modification is often performed. This review focuses on the latest achievements in the field of surface modification techniques including sol-gel, thermal spray, magnetron sputtering, electrophoretic deposition and micro-arc oxidation of biocompatible calcium phosphates (CaP) based ceramics coatings for metallic implants with emphasis on the structure, morphological characterization, phase transformation and coating composition. A reflection on the results shows that CaP coatings can be grown with the each type of techniques and a stronger fixation can be enhanced with CaP fabrication on metallic implants. Advantages and limitations of the aforementioned techniques of CaP-based coatings from the point of view of the process simplicity as well as the most important challenges of each coating techniques are highlighted. Further, the most promising method for CaP deposition was identified and a specific area for improvement was discussed.     

Recent developments in underwater wet welding

Abstract

Developments in underwater wet welding processes over the past 25 years are reviewed. Shielded metal arc welding with rutile base coated electrodes is still by far the most common wet welding process in use. Research and development of wet welding electrodes has led to improvements in the control of hydrogen content, porosity, chemical composition, and microstructure of the weld metal. Additional work is required to develop welding consumables with improved control over diffusible hydrogen and porosity. Development of techniques such as temper bead welding has allowed successful wet welding repairs on steels having carbon equivalents greater than the traditional limit of 0.40. Alternative wet welding processes such as flux cored arc welding and friction welding are under development, but have yet to become widely accepted.     

Recent developments in low-carbon sheet steels

This overview provides examples of recent areas of research related to physical metallurgy of low-carbon sheet steels. Development of new alloys and microstructures, understanding mechanical behavior in new loading regimes, and understanding microstructure evolution in response to new processing methods are shown to provide continued challenges and opportunity. Ferrous physical metallurgy remains an active and fruitful field of research.     

Recent developments of bending in Japan

Developments and researches concerning bending in Japan during the last ten years can be divided into three major subject matters; bending of plates, bending of pipes and bending of channels. In binding, of plates, the problems of forming pipes from plates by using the U-O method have been treated by practising engineers and researchers, so the forming conditions have been confirmed. On the other hand, new processes to manufacture long tubes or pipes by the successive U-O bending, a method of in-plane bending with rolling and so on, have been proposed. An analysis for bending which has been considered with sharing deformations has been presented too. In bending of pipes, experimental and theoretical researches for plastic bending of pipes have been carried out. In bending of channels, uniform bending and stretch forming for channel products have been researched experimentally and theoretically. In the following chapters, the researches and developments about the above three major subject matters of bending are described in detail.     

Recent developments of shearing in Japan

In this article, leading research and development activities of shearing in Japan are reviewed. Main contents are elucidation of shearing mechanism, theoretical analysis, tool life, burr-free blanking, precision shearing, bar cropping, pipe cutting, slitting, shearing of non-metallic materials, tool making, shearing of extremely thin sheets, etc.     

Recent developments in carbon baking technology

As the aluminum industry strives to improve productivity and efficiency, carbon baking technology is one area receiving attention. With the anode plant accounting for a significant portion of total smelter investment, completely new installations are often out of the question. But the alternative of retrofitting existing carbon baking furnaces can often provide incremental capacity, reduce fuel consumption, and cut unwanted emissions.     

Recent developments in the application of tin

As a commodity, tin has weathered a severe drop in its market value, and, at present, tin-producing countries are exporting more of the metal than was originally anticipated. Tin is utilized in a variety of significant applications, including: solder, where it has grown at the expense of lead; tinplate for food cans, where the battle between aluminum and steel is still being waged; coatings, where tin-zinc alloys are more corrosion resistant than zinc alone; and chemical production, where tin is used as a flame retardant and stabilizer in polymers. Fluctuations in tin prices would most adversely influence the fledgling chemical market, where the growth opportunities for tin diminish as the metal’s price escalates.     

铝合金厚板激光扫描填丝焊接气孔抑制

采用光纤激光对8 mm厚度的7A52铝合金板材进行对接焊接试验,分析焊缝上下组织及性能差异. 采用能谱仪（EDS）分析焊缝不同区域合金元素的烧损情况,并对焊缝和母材分别进行拉伸试验,测量焊缝显微硬度.结果表明,焊缝上部区域的显微组织比下部区域小,焊缝上部Mg,Zn 元素含量低于下部边缘;焊缝上部中心的显微硬度高于下部中心,焊缝上边缘的显微硬度小于下边缘; 焊接接头以韧性断裂为主要特征,抗拉强度为325 MPa,为母材的65.9%. 焊缝抗拉强度的降低与Mg,Zn元素的烧损、焊接应力、气孔缺陷等因素密切相关.     

Recent developments in metastable β strip alloys

The strip producibility, good fabricability, and excellent mechanical properties of β alloys make them useful for a variety of fabricated sheet metal structures on aircraft. TIMETAL 15-3 is currently used for environmental control system ducting on the Boeing 777 and, more recently, has been used on the Airbus A380. For applications that require exposure to higher temperatures, such as the exhaust assemblies, TIMETAL 21S is now used on the Boeing 777, Airbus A340, and various other civil and military aircraft. This paper was presented at the Beta Titanium Alloys of the 00’s Symposium sponsored by the Titanium Committee of TMS, held during the 2005 TMS Annual Meeting & Exhibition, February 13–16, 2005 in San Francisco, CA.     

搅拌摩擦焊在运载火箭贮箱制造中的应用与发展

随着工业技术的进步,航空航天、交通运输等领域对构件的承载能力提出了越来越高的需求,采用搅拌摩擦焊的方法对9 mm厚2A14-T4铝合金进行连接,并对高强铝合金厚板接头沿厚度方向不同区域的微观组织和力学性能进行研究 .结果表明,在转速400 r/min、焊接速度100 mm/min条件下能够获得表面成形良好的焊缝,接头抗拉强度为360 MPa,达到母材强度的83.9%. 接头微观组织沿厚度方向存在显著差异,焊缝上部、中部、下部晶粒尺寸逐渐减小,其平均直径分别为7.9,5.0和2.8 μm. 焊缝底部断口出现小而浅的等轴状韧窝.接头断裂位置和最低显微硬度均出现在接头后退侧的热力影响区;同时接头显微硬度呈现“W”形分布,且沿厚度方向分布存在差别,焊缝上部、中部、下部显微硬度最低值分别为99.9,97.9和94.7 HV.     

Recent developments in engineering γ—TiAl intermetallics

γ-TiAl based alloys are rapidly being developed for elevated temperature applications,due to their high strength,light mass and good oxidation resistance.However,th disadvantages of TiAl based alloys are low ductility and toughness at room temperature,and poor workability.Grain refinement is one of the most effective ways for improving room temperature tensile properties and hot workability of ordered TiAl based alloys.At present,the majority of research works have focused on alloy modifications through compositional controls,alloying additions,thermo-mechanical processing and production techniques.This article discusses the research status of TiAl based alloys in the aras of microstructure,alloying,processing and applications.