Download or read book Solidification Processing Mechanical Behavior of Ta W Wp Refractory Metal Base Composites written by and published by . This book was released on 1995 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research program, two solidification processing technique, that is spray atomization and deposition, and low pressure plasma spraying (LPPS) were both experimentally and theoretically studied for processing refractory metals and alloys such as tantalum alloys and tungsten, and refractory intermetallic composites, such as SiC reinforced MoSi2 composites. In this final report, the aforementioned experimental and numerical results are described and discussed in four respective sections, which are numerical analysis of droplet-gas interactions in spray atomization of Ta-(2.5w) alloy; low pressure plasma spraying of tungsten; numerical analysis of porosity evolution during low pressure plasma spraying of tungsten; and microstructure and behavior of low pressure plasma deposited SiC-reinforced MoSi2. In addition, the work on the elevated temperature deformation of 6061 aluminum alloy and SiC particulate reinforced 6061 aluminum composites is also included. jg p.1.
Download or read book Mechanical Behavior and Flow Mechanisms in Refractory Metal Composites written by and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report clearly demonstrates that the mechanical behavior of a refractory metal based composite, such as Nb-10 a/o Si alloy, can be improved considerably by tailoring the microstructure through thermomechanical processing (TMP). This desired microstructure consists of a fine grain silicide matrix reinforced with polygrain Nb particles which are elongated, oriented and aligned in a direction transverse to crack propagation. The powder processing route can achieve a fine grain structure which would exhibit high strength. But, significant improvements in fracture toughness would probably not be possible because factors such as the elongation, alignment, and orientation of the ductile reinforcement phase are critical and provide additional energy absorption mechanisms such as pull-out, interface sliding, and crack bridging. The directional solidification (DS) process can produce a composite with reinforcing phase particles of specific size, spacing, and orientation. However, in the DS material, both the matrix and the ductile particles have single grain structures, which are prone to cleavage. Therefore, TMP by hot extrusion of a DS material will result in a composite with optimum properties.
Download or read book Research in Progress written by and published by . This book was released on 1992 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rapid Solidification Technology written by T.S. Sudarshan and published by CRC Press. This book was released on 1993-12-20 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid solidification processing results in increased strength, and fracture and fatigue resistance of alloys, with concurrent improvements in mechanical, physical and chemical properties. This volume provides a systematic examination of this technology, including metallurgical aspects, processing methods, alloy design, and applications. Each chapter was prepared by a specialist for this volume. The text is well illustrated with more than 400 micrographs and schematics. More than 75 tables provide important reference data.
Download or read book Metals Abstracts written by and published by . This book was released on 1996 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metals Abstracts Index written by and published by . This book was released on 1996 with total page 1634 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solidification Processing of Metal Matrix Composites written by Nikhil Gupta and published by Wiley-TMS. This book was released on 2006-11-10 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Solidification Processing of Metal Matrix Composites" (MMCs) focuses primarily on microcomposites but also covers macrocomposites, nanocomposites and foams. There are four main areas detailed: fundamentals of solidification synthesis, which examines issues related to stir mixing, pressure infiltration, transfer of particles or fibers through gas-liquid and liquid-solid interfaces, and particle/fiber interactions with fluids; processing and microstructures, which focuses on microstructure formation during solidification of MMC under different conditions, such as nucleation, growth, heat transfer, microsegregation, macrosegregation and interactions between solidifying interfaces, particles and fibers; and, properties of solidification processing, covering the relationship between the microstructures and properties. Comparisons are made between properties of solidification processed composites and monolithic and composites made by solid and vapor phase processes. It also details the application of solidification processed MMCs, revealing current and future applications especially in automotive, aerospace, railroad, thermal management, electromechanical machinery and recreational equipment sectors.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microstructure and Mechanical Properties of Refractory Metal Alloys Formed by Field Assisted Sintering Technique FAST written by Paul Browning and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Refractory metals and their alloys are of critical importance for a large number of applications ranging from nuclear fission and fusion reactors to the defense and aerospace industries. Of the refractory metal alloys, tungsten, tantalum, and molybdenum alloys are dominant in both commercial and defense applications. Unfortunately, due to their high melting temperatures and relatively poor sinterability, formation of high-density components of these alloys is difficult, requiring either the use of time-consuming and expensive techniques such as hot isostatic pressing or post-processing such as hot extrusion and annealing to produce components acceptable for structural use. Furthermore, as components of these compounds are generally by their very nature used at elevated operating temperatures, they frequently experience failure due to recrystallization, grain growth, and creep.Field Assisted Sintering Technique (FAST), also commonly referred to as spark plasma sintering (SPS) or pulsed electric current sintering (PECS) is a promising method for formation of dense compacts of traditionally difficult to sinter materials. FAST uses a combination of elevated temperatures, pressures, and the application of an electric field to rapidly sinter components over the course of several minutes to hours. FAST is an excellent technique for rapid production of refractory alloys, as it produces near net-shaped components featuring equiaxed grain structures. As FASTs uses rapid heating and cooling rates, it is also capable of producing dense components of much finer grain sizes in comparison to traditional sintering techniques.This dissertation explores the use of FAST and alloying additions to produce refractory metal alloys featuring improved mechanical properties over current commercially available materials. Work begins by exploring the room and ultra-high temperature mechanical properties of a series of tungsten alloys (Chapter 3) attempting to make use of Ta and TiC alloying additions. W-TiC alloys are found to be promising for high-strength applications where ductility is less of an issue, and display substantial resistance to grain growth at temperatures up to1927 C (3500 F). This strengthening effect was found to be lost upon testing at 2204 C (4000 F). In contrast, a tested W-10vol%Ta alloy was found to display high strength and ductility at temperatures of 1649 C (3000 F) and higher, making this an excellent candidate material for ultrahigh temperature applications. To gain increased understanding of the microstructural effects that were resulting in observed mechanical behaviors, a detailed study of W-10vol%Ta and W-10vol%Ta-5vol%TiC alloys including optical and SEM imaging with EDS mapping, TEM imaging, X-ray diffraction, and hardness measurements was performed to examine elemental diffusion and microstructural changes in these two alloys. W-Ta cross diffusion was discovered to occur over a relatively large area on order of 10s of microns, producing a Ta interface region featuring increased hardness than that expected for pure tantalum. Interestingly, interstitial elements such as C and O were found to preferentially migrate to the center of Ta particles, producing regions displaying extremely high hardness in comparison to the surrounding ductile matrices, possibly accounting for the apparent strengthening seen in the W-10vol%Ta samples at both room and elevated temperatures.The loss of strength in W-TiC alloys at 2204 C was disappointing given their excellent grain growth resistance up to 1927 C, therefore work was done investigating the centering and mechanical behavior of W with other nanoparticle additives. This resulted in identification of oxidation of nanoparticle additions in W due to oxygen present in the matrix phase, which is in agreement with previous oxidation seen in W-TiC alloys. A Zener-type model allowed for successful description of grain growth inhibition of W during sintering with carbide particle additions, and a simple model combining the Hall-Petch and second-phase precipitate strengthening mechanisms was capable of prediction alloy hardness values with relative accuracy, alloying for tailoring of W hardness with specific nanoparticle additions to desired values.Tungsten alloys were found to be highly brittle at room temperature regardless of alloying changes, therefore work was also performed exploring room and ultra-high temperature Ta alloys (Chapter 4). This resulted in identification of Ta-10vol%W as an excellent alloy for use over a wide range of temperatures including up to temperatures in excess of 2204 C. It was further demonstrated that this alloy displayed superior mechanical properties to Ta-10vol%W produced by other commercial methods at elevated temperatures which was attributed to the improved microstructure obtained by FAST sintering in comparison to Ta-10vol%W alloys obtained by typical arc casting, forging, and heat treatment methods. Finally, as TiC nanoparticle addition was found to produce extremely strong W alloys up to 1927 C, it was of interest whether use of this alloy was possible with molybdenum, a material used at lower temperatures than tungsten for which the loss of strength seen at 2204 C would not be a concern. Sintering studies were therefore performed determining optimal sintering conditions for production of the molybdenum alloy TZM (titanium zirconium molybdenum) alloys with and without TiC addition (Chapter 5). After determining these conditions, commercial-scale 4x4 plates were sintered at optimized conditions, producing similar densities to that seen in smaller samples demonstrating potential scalability of FAST production of these alloys for commercial-scale sintering. Mechanical testing of these alloys identified the presence of high degrees of ductility in pure TZM samples and TZM-5vol%TiC samples, although this ductility was lost at 10 vol% TiC addition.
Download or read book Processing and Properties of Wear Resistant Refractory Metal Silicide Matrix Composites written by Karthikeyan S. Ganapathi and published by . This book was released on 1998 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Severe Plastic Deformation Processing of Refractory Metals by Equal Channel Angular Extrusion written by and published by . This book was released on 2008 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research efforts to develop high density refractory metals, such as Ta and W, have to a certain extent been hindered by the inability to thermomechanically process the materials to achieve key properties necessary for adequate performance, namely consistent mechanical behavior. The work presented here demonstrates the potential for W, Ta, and other polycrystalline refractory metals to be processed via equal channel angular extrusion (ECAE) to have nanocrystalline microstructures and improved mechanical behavior. Microscopy of the ECAE processed W and Ta show ~300 nm grains in the worked state and enhanced mechanical behavior. Other processing-microstructure-property relationships correlating processing, microstructure, and microhardness are reported here.
Download or read book Aerospace Structural Metals Handbook written by and published by . This book was released on 1989 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Engineering Materials 2 written by Michael F. Ashby and published by Elsevier. This book was released on 2014-06-28 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a thorough explanation of the basic properties of materials; of how these can be controlled by processing; of how materials are formed, joined and finished; and of the chain of reasoning that leads to a successful choice of material for a particular application. The materials covered are grouped into four classes: metals, ceramics, polymers and composites. Each class is studied in turn, identifying the families of materials in the class, the microstructural features, the processes or treatments used to obtain a particular structure and their design applications. The text is supplemented by practical case studies and example problems with answers, and a valuable programmed learning course on phase diagrams.
Download or read book Mechanical Alloying And Milling written by Cury Suryanarayana and published by CRC Press. This book was released on 2004-09-28 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book surveys the broad field of mechanical alloying from a scientific and technological perspective to form a timely and comprehensive resource valuable to both students and researchers. The treatment progresses from the historical background through a description of the process, the different metastable effects produced, and the mechanisms of
Download or read book Ceramic Abstracts written by American Ceramic Society and published by . This book was released on 1992 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerospace Structural Metals Handbook written by Belfour Stulen, Inc. Mechanical Properties Data Center and published by . This book was released on 1970 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Welding Metallurgy and Weldability of Nickel Base Alloys written by John C. Lippold and published by John Wiley & Sons. This book was released on 2011-09-20 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most up-to-date coverage of welding metallurgy aspects and weldability issues associated with Ni-base alloys Welding Metallurgy and Weldability of Nickel-Base Alloys describes the fundamental metallurgical principles that control the microstructure and properties of welded Ni-base alloys. It serves as a practical how-to guide that enables engineers to select the proper alloys, filler metals, heat treatments, and welding conditions to ensure that failures are avoided during fabrication and service. Chapter coverage includes: Alloying additions, phase diagrams, and phase stability Solid-solution strengthened Ni-base alloys Precipitation strengthened Ni-base alloys Oxide dispersion strengthened alloys and nickel aluminides Repair welding of Ni-base alloys Dissimilar welding Weldability testing High-chromium alloys used in nuclear power applications With its excellent balance between the fundamentals and practical problem solving, the book serves as an ideal reference for scientists, engineers, and technicians, as well as a textbook for undergraduate and graduate courses in welding metallurgy.
