Download or read book The Effect of Composition on the Mechanism of Continuous Recrystallization and Superplastic Response of Aluminum scandium Alloys written by Edwin Luther Bradley and published by . This book was released on 1992 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of Composition on the Mechanism of Continuous Recrystallization and Superplastic Response of Aluminum scandium Alloys written by and published by . This book was released on 1993 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: The continuous recrystallization (CRX) appears to be fundamental in Al-Sc because it occurs irrespective of solute composition. It appears to be due to a combination of subgrain coalescence at low strains and incorporation of additional dislocations generated during grain boundary sliding at higher strains when the misorientation has increased sufficiently. Alloying additives such as Mg, Li are more important with respect to deformation after CRX is completed. Mg, and to a lesser extent Li, affect the max m-values (strain-rate sensitivities) in Al-Sc by changing the melting points (mp). Max m- values correlate inversely with mp so that the alloy with the greatest Mg had the highest m-values and lowest mp; the stress is raised at which power-law creep and breakdown occurs. The power-law breakdonw at much lower stresses in Al-0.5Sc and Al-1.2Li-0.5Sc causes the m-value to decrease more rapidly with strain rate. Al alloys for commercial superplastic applications should contain elements that raise the power-law strength so that the m-values are maximized while preserving the post-formed mechanical properties. Refs, figs, tabs.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book Government Reports Annual Index written by and published by . This book was released on 1994 with total page 1220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1994 with total page 658 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 1995 with total page 1596 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanisms Operating During Continuous Dynamic Recrystallization in an Aluminum 4magnesium 0 3scandium Alloy written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metals Abstracts written by and published by . This book was released on 1998 with total page 1042 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1994 with total page 876 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Grain Refinement and Superplasticity in Aluminum Magnesium Alloys written by Ahmed Ahmed Abou-Salama and published by . This book was released on 1987 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous research had demonstrated superplastic behavior in aluminum-magnesium alloys of high magnesium content to result from deformation processing to an initially non recrystallized condition. Analysis here of those data has demonstrated that such a result may be understood in terms of constitutive equations developed for fine-grained materials and that the constitutive equations are applicable to materials achieving grain boundary misorientations in the range of only 2 to 7 by a process of continuous recrystallization. The constitutive equations provide a basis for analysis of anomalous temperature dependence of the strength and of the activation energy for plastic deformation seen as well in this work. A study of the separate effects of processing variables has lead to a model for continuous recrystallization during deformation processing. This model considers recovery of dislocations to sub-boundaries to be the critical step in this process. Application of this model to development of advanced aluminum alloys for air frame structural applications will result in increased weight savings by such processing methods. Theses Keywords: Superplasticity; Aluminum magnesium alloys; Thermomechanical processing; Microstructural evolution; Continuous recrystallization; Microstructural instability; Grain growth.
Download or read book The Influence of Warm Rolling Parameters Temperature and Reheating Time Between Passes on the Superplastic Response of Al Mg Alloys written by George J Kuhnert (Jr) and published by . This book was released on 1988 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of rolling temperature and reheating interval between consecutive rolling passes on the superplastic response of two Al-Mg alloys were investigated. The alloys were Al-8%Mg0.1%Zr and Al-10%Mg-0.1%Zr (wt. pct.). The effects of varying the process parameters were observed on resultant superplastic ductility during testing at 300 C. The data support a model for microstructure evolution during processing by a mechanism of continuous recrystallization (CRX). The model for CRX assumes that dislocations recover to sub boundaries which are stabilized by precipitates, of size on the order of one micron, located at nodes of the substructure. Continuous recrystallization, Superplasticity, Reheating interval rolling temperature. (jes).
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1020 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1991 with total page 1454 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book The Roles of Strain and Reheating Interval in Continuous Recrystallization During the Thermomechanical Processing by Warm Rolling of an Al Mg Alloy written by and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation into the influence of rolling strain and into the variation of properties and structure during reheating intervals between rolling passes in the thermomechanical processing of an Aluminum-9.89 Magnesium-0.09 Zirconium alloy (composition in weight percent) was conducted. Superplastic ductilities up to approximately 1120 percent were achieved by processing to a total strain of 2.5 utilizing a reheating interval of 30 minutes. Conversely, rolling to lesser values of strain with the same reheating interval or rolling to a strain of 2.5 and using a 5 minute reheating interval produced ductilities less than 400 percent. A strong correlation was demonstrated between results achieved and a qualitative model for continuous recrystallization during thermomechanical processing previously proposed. Keywords: Superplasticity, Aluminum-magnesium alloys, Continuous recrystallization, Theses, Deformation, Aerospace industry, TMP. (JG).
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.
