Download or read book Initial Dislocation Structure and Dynamic Dislocation Multiplication in Mo Single Crystals written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Initial dislocation structure in annealed high-purity Mo single crystals and deformation substructure in a crystal subjected to 1% compression have been examined and studied in order to investigate dislocation multiplication mechanisms in the early stages of plastic deformation. The initial dislocation density is in a range of 106 (almost equal to) 107 cm−2, and the dislocation structure is found to contain many grown-in superjogs along dislocation lines. The dislocation density increases to a range of 108 (almost equal to) 109 cm−2, and the average jog height is also found to increase after compressing for a total strain of 1%. It is proposed that the preexisting jogged screw dislocations can act as (multiple) dislocation multiplication sources when deformed under quasi-static conditions. Both the jog height and length of link segment (between jogs) can increase by stress-induced jog coalescence, which takes place via the lateral migration (drift) of superjogs driven by unbalanced line-tension partials acting on link segments of unequal lengths. Applied shear stress begins to push each link segment to precede dislocation multiplication when link length and jog height are greater than critical lengths. This dynamic dislocation multiplication source is subsequently verified by direct simulations of dislocation dynamics under stress to be crucial in the early stages of plastic deformation in Mo single crystals.
Download or read book Dislocation Multiplication in the Early Stage of Deformation in Mo Single Crystals written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Initial dislocation structure in annealed high-purity Mo single crystals and deformation substructure in a crystal subjected to 1% compression have been examined and studied using transmission electron microscopy (TEM) techniques in order to investigate dislocation multiplication mechanisms in the early stage of plastic deformation. The initial dislocation density is in a range of 106 (almost equal to) 107 cm−2, and the dislocation structure is found to contain many grown-in superjogs along dislocation lines. The dislocation density increases to a range of 108 (almost equal to) 109 cm−2, and the average jog height is also found to increase after compressing for a total strain of 1%. It is proposed that the preexisting jogged screw dislocations can act as (multiple) dislocation multiplication sources when deformed under quasi-static conditions. The jog height can increase by stress-induced jog coalescence, which takes place via the lateral migration (drift) of superjogs driven by unbalanced line-tension partials acting on link segments of unequal lengths. The coalescence of superjogs results in an increase of both link length and jog height. Applied shear stress begins to push each link segment to precede dislocation multiplication when link length and jog height are greater than critical lengths. This ''dynamic'' dislocation multiplication source is suggested to be crucial for the dislocation multiplication in the early stage of plastic deformation in Mo.
Download or read book Fundamental Aspects of Dislocation Interactions written by G. Kostorz and published by Elsevier. This book was released on 2013-09-03 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental Aspects of Dislocation Interactions: Low-Energy Dislocation Structures III covers the papers presented at a European Research Conference on Plasticity of Materials-Fundamental Aspects of Dislocation Interactions: Low-Energy Dislocation Structures III, held on August 30-September 4, 1992 in Ascona, Switzerland. The book focuses on the processes, technologies, reactions, transformations, and approaches involved in dislocation interactions. The selection first offers information on work softening and Hall-Petch hardening in extruded mechanically alloyed alloys and dynamic origin of dislocation structures in deformed solids. Discussions focus on stress-strain behavior in relation to composition, structure, and annealing; comparison of stress-strain curves with work softening theory; sweeping and trapping mechanism; and model of dipolar wall structure formation. The text then ponders on plastic instabilities and their relation to fracture and dislocation and kink dynamics in f.c.c. metals studied by mechanical spectroscopy. The book takes a look at misfit dislocation generation mechanisms in heterostructures and evolution of dislocation structure on the interfaces associated with diffusionless phase transitions. Discussions focus on dislocation representation of a wall of elastic domains; equation of equilibrium of an elastic domain; transformation of dislocations; and theoretical and experimental background. The selection is a valuable reference for readers interested in dislocation interactions.
Download or read book Advances in Computational Engineering Sciences 2000 written by and published by . This book was released on 2000 with total page 968 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dislocation Dynamics written by Alan R. Rosenfield and published by . This book was released on 1968 with total page 806 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multiscale Phenomena in Materials Experiments in Modeling Volume 578 written by I. M. Robertson and published by Mrs Proceedings. This book was released on 2000-07-20 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.
Download or read book Dislocations in Solids Dislocations in crystals written by Frank Reginald Nunes Nabarro and published by North Holland. This book was released on 1979 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dislocation Dynamics and Plasticity written by Taira Suzuki and published by Springer. This book was released on 1991 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the 1950s the direct observation of dislocations became possible, stimulat ing the interest of many research workers in the dynamics of dislocations. This led to major contributions to the understanding of the plasticity of various crys talline materials. During this time the study of metals and alloys of fcc and hcp structures developed remarkably. In particular, the discovery of the so-called in ertial effect caused by the electron and phonon frictional forces greatly influenced the quantitative understanding of the strength of these metallic materials. Statis tical studies of dislocations moving through random arrays of point obstacles played an important role in the above advances. These topics are described in Chaps. 2-4. Metals and alloys with bcc structure have large Peierls forces compared to those with fcc structure. The reasons for the delay in studying substances with bcc structure were mostly difficulties connected with the purification techniques and with microscopic studies of the dislocation core. In the 1970s, these difficulties were largely overcome by developments in experimental techniques and computer physics. Studies of dislocations in ionic and covalent bonding materials with large Peierls forces provided infonnation about the core structures of dislocations and their electronic interactions with charged particles. These are the main subjects in Chaps. 5-7.
Download or read book Computer Modeling in Engineering Sciences written by and published by . This book was released on 2002 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Observation of Dislocations and Plasticity in Mineral Crystals with Special Reference to Plagioclase written by Karl Earl Seifert and published by . This book was released on 1965 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Dislocations written by Derek Hull and published by Butterworth-Heinemann. This book was released on 1995 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an essential basis for an understanding of many of the physical and mechanical properties of crystalline solids. This new edition has been extensively revised and updated to reflect developments in the understanding of the subject, whilst retaining the clarity and comprehensibility of the original text. Substantial new sections are included, notably in topics relating to experiemental technqiues, the elastic properties of dislocations, forces on dislocations, dislocations in particular crystal structures, the dislocation content of boundaries, and the strength of crystalline solids.
Download or read book A Report on the Use of Weak Shock Wave Profiles and 3 D Dislocation Dynamics Simulations for Validation of Dislocation Multiplication and Mobility in the Phonon Drag Regime written by D. Lassila and published by . This book was released on 2004 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamically loaded gas gun experiments were performed to validate the predictive capabilities of 3-D dislocation dynamics (DD) code simulations at very high strain rates and dislocation velocities where the phonon drag mechanism will be dominant. Experiments were performed in the weak-shock regime on high-purity Mo single crystals with [001] compression axes. We have also performed shock-recovery experiments and are in the process of analyzing the dislocation structure generated by the weak-shock using transmission electron microscopy (TEM), which will also be used to validate the dislocation structure predicted by the DD simulations. The DD simulations being performed at Washington State University by Prof. H. Zbib and co-workers will be compared to the experimentally measured wave profiles, thereby validating mechanisms of dislocation generation and motion. Some DD simulation results are presented to demonstrate the feasibility of using a combined experimental/simulation effort for the validation of dislocation generation and mobility physics issues in the phonon drag regime.
Download or read book Dislocation Generation and Motion in B2 NiAl Single Crystals written by Biman Ghosh and published by . This book was released on 2003 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dislocations in Solids written by Hiroshi Suzuki and published by CRC Press. This book was released on 2023-03-08 with total page 691 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume comprises the Proceedings of the Yamada Conference IX on Dislocations in Solids, held in August 1984 in Tokyo. The purpose of the conference was two-fold: firstly to evaluate the increasing data on basic properties of dislocations and their interaction with other types of defects in solids and, secondly, to increase understanding of the material properties brought about by dislocation-related phenomena. Metals and alloys, semi-conductors and ions crystals were discussed. One of the important points of contention was the electronic state at the core of dislocation. Another was the dislocation model of amorphous structure.
Download or read book Dislocations in Solids written by Frank R.N. Nabarro and published by Elsevier. This book was released on 2002-12-05 with total page 687 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dislocations are lines of irregularity in the structure of a solid analogous to the bumps in a badly laid carpet. Like these bumps, they can be easily moved, and they provide the most important mechanism by which the solid can be deformed. They also have a strong influence on crystal growth and on the electronic properties of semiconductors.
Download or read book Dislocation Dynamics and Mechanical Properties of Crystals written by Edward Nadgornyi and published by Elsevier Science & Technology. This book was released on 1988 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dislocations in Solids Applications and recent advances written by Frank Reginald Nunes Nabarro and published by . This book was released on 1979 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series offers a comprehensive review of the entire study of dislocations. It is the first in over a decade to effectively focus attention on the influence of dislocations on all physical and metallurgical properties. Whereas, formerly, it was possible to assemble our entire knowledge of dislocations into a single volume, the current scope of knowledge has increased to such an extent as to make a series of books a matter of necessity.
