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Superplasticity At High Strain Rates In Aluminum Alloys
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Book Synopsis Superplasticity at High Strain Rates in Aluminum Alloys by :
Download or read book Superplasticity at High Strain Rates in Aluminum Alloys written by and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The detailed experimental data of microstructural developments during the optimum thermomechanical treatments and superplastic properties in the wide deformation range have been investigated on fourteen P/M aluminum alloys with various chemical matrix compositions and different typed precipitate particles. It was revealed that the differences in both size and volume among the second phase particles, which increase with content of Zr, Cr, Mn or Y, affect on the recrystallization behavior, grain size and superplastic properties of these aluminum alloys. Some of them exhibited high-strain-rate superplasticity, so the optimizing processing methods in this proposal were very powerful to provide the desired structures required for high-strain-rate superplasticity in these aluminum alloys. A theoretical interpretation, based on the experimental data by tensile test and the observed grain sizes, has been revealed that values in activation energy for all alloysare between 140 and 155 kJmol-1, which are similar to that for lattice self-diffusion of aluminum. Each mechanical data of each alloy can be presented by a single equation. It was postulated that superplastic flow in these P/M aluminum alloys was fundamentally controlled by a grain boundary sliding mechanism accommodated by dislocation climb controlled by lattice self-diffusion. However, for the statically recrystallized alloys consisted of the high-angle grain boundaries, the Dorn typed equation presents n=2, p=2 and D=D sub L, whereas for the dynamically recrystallized alloys with the low-angle grain boundaries, n=3, p=2 and D=D sub L. The consideration for deformation mechanisms with the accommodation helper by such a liquid has been applied on the aluminum alloys, but it remained unclear.
Book Synopsis Superplasticity and Superplastic Forming II by : Amit Kumar Ghosh
Download or read book Superplasticity and Superplastic Forming II written by Amit Kumar Ghosh and published by Minerals, Metals, & Materials Society. This book was released on 1995 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of superplasticity and superplastic forming (SPF) has been increasing steadily over the past 15 years. This volume examines the current state of the technology with a focus on technological applications of superplastic forming and the mechanistic behaviour of superplastic materials.
Book Synopsis Developing a High Strain Rate Superplastic Forming Capability in Aluminum Alloys by :
Download or read book Developing a High Strain Rate Superplastic Forming Capability in Aluminum Alloys written by and published by . This book was released on 2003 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The applications for superplastic forming (SPF) are currently limited because the strain rates involved in the forming process tend to be relatively slow (typically 10(exp -3)-10 (exp -1) 1 s(exp -1). There would be a very significant increase in the applications for SPF if the forming rates were increased to 10(exp -1) 1 s(exp -1). It can be shown on theoretical grounds that SPF-may be achieved at faster rates by reducing the grain size of the superplastic material. Unfortunately, it is generally not possible to achieve grain sizes as small as the submicrometer level using conventional thermo-mechanical processing. This paper demonstrates the potential for achieving ultrafine grain sizes through the application of severe plastic deformation. It is shown that two aluminum- based alloys exhibit superplastic elongations at very rapid strain rates when the alloys are processed using the procedure of Equal-Channel Angular Pressing (ECAP) in which the samples are pressed through a die containing a channel bent into an L-shaped configuration. It is demonstrated also that samples processed by ECAP can be Superplastically formed at very rapid strain rates.
Book Synopsis Superplasticity in Aluminum Alloys by :
Download or read book Superplasticity in Aluminum Alloys written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have characterized in the Al-Mg system the microstructure and mechanical properties of a cold-rolled Al-6Mg-0.3Sc alloy. The alloy exhibited superplasticity at relatively high strain rates (about 10-2 s-1). At a strain rate of 10-2 s-1 there exists a wide temperature range (475-520'C) within which the tensile elongation is over 1000%. There also exists a wide strain rate range (10-3 - 10-1 s-1) within which the tensile elongation is over 500%. The presence of Sc in the alloy results in a uniform distribution of fine coherent Al3SC precipitates which effectively pin grain and subgrain boundaries during static and continuous recrystallization. As a result, the alloy retains its fine grain size (about 7 micron), even after extensive superplastic deformation (>1000%). During deformation, dislocations Mg with a high Schmidt factor slip across subgrains but are trapped by subgrain boundaries, as a result of the strong pining of Al3Sc. This process leads to the conversion of low-angled subgrain boundaries to high-angled grain boundaries and the subsequent grain boundary sliding, which produces superelasticity. A model is proposed to describe grain boundary sliding accommodated by dislocation glide across grains with a uniform distribution of coherent precipitates. The model predictions is consistent with experimental observations.
Book Synopsis Aluminum-Lithium Alloys by : S. Balasivanandha Prabu
Download or read book Aluminum-Lithium Alloys written by S. Balasivanandha Prabu and published by Elsevier Inc. Chapters. This book was released on 2013-09-20 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the late 1950s, lithium is being used as an alloying element in aluminum. Their excellent ductility, which allows superplastic forming, along with their ability to decrease the density, makes aluminum-lithium alloys a primary choice for many structural applications in aerospace industry. This chapter initially discusses the processes and mechanisms that give rise to significant plasticity/Superplasticity in these alloy systems. The superplastic behavior of Al-Li alloys and their applications in forming are then discussed. The thickness variation during superplastic forming strongly depends on the peak strain rate sensitivity index (m) of the material, and an increase in the m value reduces the thickness variation in the formed component. The factors that help increase the value of m are enumerated. Superplastic forming is carried out at temperatures ≥ 0.5 Tm (Tm is the absolute melting temperature), often closer to 0.7 − 0.8 Tm. Significant cavitation and grain growth are present at such high temperatures. This has ushered in low temperature superplastic forming by the production of ultra-fine grain sizes via dispersion strengthening and severe plastic deformation (SPD). The promise of superplastic forming of Al-Li alloys for the future and the factors including cost that limit the use of Al-Li alloys are also discussed.
Book Synopsis Superplasticity in Metals and Ceramics by : T. G. Nieh
Download or read book Superplasticity in Metals and Ceramics written by T. G. Nieh and published by Cambridge University Press. This book was released on 1997-01-23 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes advances in the field of superplasticity, the ability of certain materials to undergo very large tensile strains. This phenomenon has increasing commercial applications, but also presents a fascinating scientific challenge in attempts to understand the physical mechanisms that underpin it. The authors emphasize the materials aspects of superplasticity. Beginning with a brief history of the phenomenon, they describe the two major types of superplasticity-- fine-structure and internal-stress superplasticity-- and discuss their operative mechanisms. They also present microstructural factors controlling the ductility and fracture in superplastic materials. Observations of superplasticity in metals (including aluminum, magnesium, iron, titanium and nickel), ceramics (including monoliths and composites), intermetallics (including iron, nickel, and titanium base), and laminates are thoroughly described. This is a valuable text for graduate students and researchers in materials science and engineering.
Book Synopsis Fundamentals of Creep in Metals and Alloys by : Michael E. Kassner
Download or read book Fundamentals of Creep in Metals and Alloys written by Michael E. Kassner and published by Elsevier. This book was released on 2004-04-06 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: * Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials * Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures * Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussion Understanding the strength of materials at a range of temperatures is critically important to a huge number of researchers and practitioners from a wide range of fields and industry sectors including metallurgists, industrial designers, aerospace R&D personnel, and structural engineers. The most up-to date and comprehensive book in the field, Fundamentals of Creep in Metals and Alloys discusses the fundamentals of time-dependent plasticity or creep plasticity in metals, alloys and metallic compounds. This is the first book of its kind that provides broad coverage of a range of materials not just a sub-group such as metallic compounds, superalloys or crystals. As such it presents the most balanced view of creep for all materials scientists. The theory of all of these phenomena are extensively reviewed and analysed in view of an extensive bibliography that includes the most recent publications in the field. All sections of the book have undergone extensive peer review and therefore the reader can be sure they have access to the most up-to-date research, fully interrogated, from the world’s leading investigators. · Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials· Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures· Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussion
Book Synopsis Superplasticity of Alloys, Intermetallides and Ceramics by : Oscar A. Kaibyshev
Download or read book Superplasticity of Alloys, Intermetallides and Ceramics written by Oscar A. Kaibyshev and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superplasticity is shown to be a universal phenomenon in materials ranging from metals and intermetallics to ceramics. Superplastic deformation facilitates the production of materials with specifically chosen properties. This is illustrated using the examples of Mg-, Al-, and Ti-based commercial alloys, steels, and superalloys. Some of the strenghts of this book are: the broad range of materials studied, the reduction of scientific results to a form suitable for the practitioner, a profound physical analysis of the phenomenon, a new approach to superplastic treatment as a kind of strain-heat treatment, the presentation of new data on superplastic flow and on production techniques of micro- and submicrocrystalline structures.
Book Synopsis An Approach to Low Temperature High Strain Rate Superplasticity in Aluminum Alloy 2090 by : Michael Wayne Reedy
Download or read book An Approach to Low Temperature High Strain Rate Superplasticity in Aluminum Alloy 2090 written by Michael Wayne Reedy and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Research and Application of Advanced Superplasticity in Ultrafine Grained Aluminum Alloys and Composites by :
Download or read book Research and Application of Advanced Superplasticity in Ultrafine Grained Aluminum Alloys and Composites written by and published by . This book was released on 1999 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrafine grained Al 1420 alloy and Al 6061 composite were processed by severe plastic deformation. The requirements to achieve high strain rate superplasticity in the UFG Al 1420 alloy are discussed. Examples of complex shape articles fabricated by high strain rate superplastic forming are demonstrated.
Book Synopsis Grain Boundary Development in Superplastic Aluminum Alloys by : Michael Edward McMahon
Download or read book Grain Boundary Development in Superplastic Aluminum Alloys written by Michael Edward McMahon and published by . This book was released on 1996-12-01 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superplasticity may be defined as the capability of certain polycrystalline materials to deform to extensive plastic elongations prior to failure, often without formation of a neck. Typically, superplasticity refers to tensile elongations greater than 200%, although some elongations have been reported in excess of 5000% Ref 1. While it has been suggested that bronze metals in use in ancient civilizations may have possessed superplastic properties Ref 2, most historical reviews credit the modern-day documentation of superplastic behavior to a paper published in the Journal of the Institute of Metals by G.D. Bengough in 1912 which described extensive elongations in brass Ref 3. Recognition of a stress and strain-rate relationship was first presented qualitatively in a paper by Rosenhain in 1920 which examined a near eutectic Zn- Al-Cu alloy Ref 4. Photomicrographs detailing superplastic grain structures in eutectic Sn-Pb and Bi-Pb alloys deformed to elongations of 2000% were presented in 1934 by Pearson Ref 5. This study was the first to identify an equiaxed grain morphology in the deformed regions and suggest that grain boundary migration may be involved in the deformation processes.
Book Synopsis Superplasticity by : Oskar Akramovich Kaĭbyshev
Download or read book Superplasticity written by Oskar Akramovich Kaĭbyshev and published by . This book was released on 2005 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: The remarkable technology of superplastic forming was developed and perfected in the former Soviet Union. This volume, written by two Russian scientists at the Institute for Metals Superplasticity Problems in Ufa, Bashkortostan, Russia (of which Kaibyshev was the former director), presents a detailed and up-to-date treatment of the technology, with particular attention to the production of ultrafine grain materials, their use in superplastic shaping and forming, practical aspects of the process, and new developments in submicrocrystalline and nanocrystalline materials production. The comprehensive bibliography of the largely Russian literature will be a valuable resource for the serious scientist. Specialists in machine building and metallurgy, as well as graduate students and researchers will be the book's audience. Annotation :2004 Book News, Inc., Portland, OR (booknews.com).
Book Synopsis Relationship Between High-Strain-Rate Superplasticity and Interface Microstructure in Aluminum Alloy Composites by :
Download or read book Relationship Between High-Strain-Rate Superplasticity and Interface Microstructure in Aluminum Alloy Composites written by and published by . This book was released on 1999 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Al alloy composites reinforced with Si3N4 or SiC have been reported to exhibit superplasticity at high strain rate of faster than 1x 10-2s-1. It has been shown in many aluminum alloy composites that the optimum superplastic temperature coincides with an incipient melting temperature. The coincidence suggests a contribution of the liquid phase to the superplasticity mechanism. This paper shows a direct evidence of partial melting along matrix grain boundaries and matrix-reinforcement interfaces. Based on the obtained results, the role of the liquid phase in the high-strain-rate superplasticity is discussed. The sample was Al-Mg (5052) alloy reinforced with 20vol% Si3N4 particles, fabricated by a powder metallurgy process. The sample showed an excellent superplasticity under the conditions given in Table 1. Partial melting was confirmed to occur at 821 K by differentail scanning calorimetry. The microstructural changes during heating were observed in situ by TEM using a heating stage. The structure of interfaces and grain boundaries was observed by HREM. Chemical analysis was performed with EDS attached to VG-STEM. A bright-field image of the composite is shown in Fig. 1. Notice that the edge of the Si3N4 particles are fragmented. Fig. 2 (a) shows a selected-area diffraction pattern taken at 821 K.A halo ring appears at this temperature, indicating partial melting. Fig. 2 (b) shows a dark- field image with an inverted contrast, taken from a part of the halo ring. The location of partial melting can be identified by a dark contrast along the matrix grain boundaries and the matrix- reinforcement interfaces. Above this temperature, grain-boundary corners become a rounded shape caused by the formation of the liquid phase at triple grain junctions. Figure 3 shows a concentration profile across a matrix-reinforcement interface. The left side is the aluminum matrix and the right is a Si3N4 particle. In the middle in between two dotted lines, there is a region where the Al and Si concentrations take intermediate flat values, indicating the formation of an interface phase. Mg segregation at the location of the left dotted line is also observed. This solute segregation is considered to be a cause for partial melting. The crystal structure of the interface phase was investigated by HREM and shown in Fig. 4. The figure shows the Al matrix and the interface phase. The interface is severely serrated and may become a stress concentration site during deformation. FFT of various regions reveals that the interface phase is composed of MgO, Al2MgO4, and Mg2Si. In the present work, partial melting was observed along interfaces and grain boundaries. Solute segregation is suggested to be the cause for partial melting. The liquid phase is considered to act as a stress accommodation site that can prevent cavitation failure at the serrated interfaces and triple grain junctions.
Book Synopsis High Temperature Flow and Failure Processes in a Fine-grained Superplastic 7475 Aluminum Alloy by : Mahidhara Kameswara Rao
Download or read book High Temperature Flow and Failure Processes in a Fine-grained Superplastic 7475 Aluminum Alloy written by Mahidhara Kameswara Rao and published by . This book was released on 1985 with total page 642 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Superplasticity in Metals and Ceramics by : T. G. Nieh
Download or read book Superplasticity in Metals and Ceramics written by T. G. Nieh and published by Cambridge University Press. This book was released on 1997-01-23 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: A materials engineering monograph in the Cambridge Solid State Science Series, first published in 1997.
Book Synopsis High Strain Rate Superplasticity of Aluminium-magnesium Alloys by : Andrew William Harrison
Download or read book High Strain Rate Superplasticity of Aluminium-magnesium Alloys written by Andrew William Harrison and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Superplasticity in Metals, Ceramics, and Intermetallics: Volume 196 by : M. J. Mayo
Download or read book Superplasticity in Metals, Ceramics, and Intermetallics: Volume 196 written by M. J. Mayo and published by Mrs Proceedings. This book was released on 1990 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.
