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 Containing Papers Presented at a European Research Conference on Plasticity of Materials Fundamental Aspects of Dislocation Interactions Low Energy Dislocation Structures III written by Gernot Kostorz and published by . This book was released on 1993 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasticity of Materials Fundamental Aspects of Dislocation Interactions written by G Kostorz and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Aspects of Dislocation Interactions written by H. A. Calderon and published by . This book was released on 1993 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low energy Dislocation Structures Three written by and published by . This book was released on 1993 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Aspects of Dislocation Theory written by John Arthur Simmons and published by . This book was released on 1970 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Aspects of Dislocation Interactions written by Gernot Kostorz and published by . This book was released on 1993 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Papers Presented at a European Research Conference on Plasticity of Materials Fundamental Aspects of Dislocation Interactions written by G. Kostorz and published by . This book was released on 1993 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental aspects of dislocation written by and published by . This book was released on 1993 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Plasticity of Metals at the Sub micrometer Scale and Dislocation Dynamics in a Thin Film written by Seok Woo Lee and published by Stanford University. This book was released on 2011 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanotechnology has played a significant role in the development of useful engineering devices and in the synthesis of new classes of materials. For the reliable design of devices and for structural applications of materials with micro- or nano-sized features, nanotechnology has always called for an understanding of the mechanical properties of materials at small length scales. Thus, it becomes important to develop new experimental techniques to allow reliable mechanical testing at small scales. At the same time, the development of computational techniques is necessary to interpret the experimentally observed phenomena. Currently, microcompression testing of micropillars, which are fabricated by focused-ion beam (FIB) milling, is one of the most popular experimental methods for measuring the mechanical properties at the micrometer scale. Also, dislocation dynamics codes have been extensively developed to study the local evolution of dislocation structures. Therefore, we conducted both experimental and theoretical studies that shed new light on the factors that control the strength and plasticity of crystalline materials at the sub-micrometer scale. In the experimental work, we produced gold nanopillars by focused-ion beam milling, and conducted microcompression tests to obtain the stress-strain curves. Firstly, the size effects on the strength of gold nanopillars were studied, and "Smaller is Stronger" was observed. Secondly, we tried to change the dislocation densities to control the strength of gold nanopillars by prestraining and annealing. The results showed that prestraining dramatically reduces the flow strength of nanopillars while annealing restores the strength to the pristine levels. Transmission electron microscopy (TEM) revealed that the high dislocation density (~1015 m-2) of prestrained nanopillars significantly decreased after heavy plastic deformation. In order to interpret this TEM observation, potential dislocation source structures were geometrically analyzed. We found that the insertion of jogged dislocations before relaxation or enabling cross-slip during plastic flow are prerequisites for the formation of potentially strong natural pinning points and single arm dislocation sources. At the sub-micron scale, these conditions are most likely absent, and we argue that mobile dislocation starvation would occur naturally in the course of plastic flow. Two more outstanding issues have also been studied in this dissertation. The first involves the effects of FIB milling on the mechanical properties. Since micropillars are made by FIB milling, the damage layer at the free surface is always formed and would be expected to affect the mechanical properties at a sub-micron scale. Thus, pristine gold microparticles were produced by a solid-state dewetting technique, and the effects of FIB milling on both pristine and prestrained microparticles were examined via microcompression testing. These experiments revealed that FIB milling significantly reduces the strength of pristine microparticles, but does not alter that of prestrained microparticles. Thus, we confirmed that if there are pre-existing mobile-dislocations present in the crystal, FIB milling does not affect the mechanical properties. The second issue is the scaling law commonly used to describe the strength of micropillars as a function of sample size. For the scaling law, the power-law approximation has been widely used without understanding fundamental physics in it. Thus, we tried to analyze the power-law approximation in a quantitative manner with the well-known single arm source model. Material parameters, such as the friction stress, the anisotropic shear modulus, the magnitude of Burgers vector and the dislocation density, were explored to understand their effects on the scaling behavior. Considering these effects allows one to rationalize the observed material-dependent power-law exponents quantitatively. In another part of the dissertation, a computational study of dislocation dynamics in a free-standing thin film is described. We improved the ParaDiS (Parallel Dislocation Simulator) code, which was originally developed at the Lawrence Livermore National Laboratory, to deal with the free surface of a free-standing thin film. The spectral method was implemented to calculate the image stress field in a thin film. The faster convergence in the image stress calculation were obtained by employing Yoffe's image stress, which removes the singularity of the traction at the intersecting point between a threading dislocation and free surface. Using this newly developed code, we studied the stability of dislocation junctions and jogs, which are the potential dislocation sources, in a free standing thin film of a face-centered-cubic metal and discussed the creation of a dislocation source in a thin film. In summary, we have performed both microcompression tests and dislocation dynamics simulations to understand the dislocation mechanisms at the sub-micron scale and the related mechanical properties of metals. We believe that these experimental and computational studies have contributed to the enhancement of our fundamental knowledge of the plasticity of metals at the sub-micron scale.
Download or read book Crystal Plasticity Finite Element Methods written by Franz Roters and published by John Wiley & Sons. This book was released on 2011-08-04 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by the leading experts in computational materials science, this handy reference concisely reviews the most important aspects of plasticity modeling: constitutive laws, phase transformations, texture methods, continuum approaches and damage mechanisms. As a result, it provides the knowledge needed to avoid failures in critical systems udner mechanical load. With its various application examples to micro- and macrostructure mechanics, this is an invaluable resource for mechanical engineers as well as for researchers wanting to improve on this method and extend its outreach.
Download or read book Dislocation Dynamics and Plasticity written by Taira Suzuki and published by Springer Science & Business Media. This book was released on 2013-03-07 with total page 237 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 Dislocations and Plastic Deformation written by I. Kovács and published by Elsevier. This book was released on 2016-07-08 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dislocations and Plastic Deformation deals with dislocations and plastic deformation, and specifically discusses topics ranging from deformation of single crystals and dislocations in the lattice to the fundamentals of the continuum theory, the properties of point defects in crystals, multiplication of dislocations, and partial dislocations. The effect of lattice defects on the physical properties of metals is also considered. Comprised of nine chapters, this book begins by providing a short and, where possible, precise explanation of dislocation theory. The first six chapters discuss the properties of dislocations and point defects both in crystals and in an elastic continuum. The reader is then introduced to some applications of dislocation theory that show, for instance, the difficulties involved in understanding the hardening of alloys and the work-hardening of pure metals. This book concludes by analyzing the effect of heat treatment on the defect structure in metals. This text will be of interest to students and practitioners in the field of physics.
Download or read book Theory of Dislocations written by Peter M. Anderson and published by Cambridge University Press. This book was released on 2017-01-16 with total page 721 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive understanding of the nucleation, motion, and interaction between crystalline defects called dislocations.
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 Physical Basis of Plasticity in Solids written by Jean-Claude Toldano and published by World Scientific. This book was released on 2012 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the physical mechanism of the plastic deformation of solids, which relies essentially on the occurrence and motion of dislocations. These are linear defects, specific of crystalline solids whose motion under external stresses explains the relative ease by which solids (metals in particular) can be deformed in order to give them desired shapes. The objective is to introduce the topic to undergraduate students, restricting to the main ideas and showing their relevance in interpreting phenomena well known to everyone (e.g. why are certain metals harder than others?), and finally training the students in the practice of calculating the simplest properties of dislocations.
Download or read book Plasticity written by P.M. Dixit and published by CRC Press. This book was released on 2014-10-23 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores the Principles of Plasticity Most undergraduate programs lack an undergraduate plasticity theory course, and many graduate programs in design and manufacturing lack a course on plasticity—leaving a number of engineering students without adequate information on the subject. Emphasizing stresses generated in the material and its effect, Plasticity: Fundamentals and Applications effectively addresses this need. This book fills a void by introducing the basic fundamentals of solid mechanics of deformable bodies. It provides a thorough understanding of plasticity theory, introduces the concepts of plasticity, and discusses relevant applications. Studies the Effects of Forces and Motions on Solids The authors make a point of highlighting the importance of plastic deformation, and also discuss the concepts of elasticity (for a clear understanding of plasticity, the elasticity theory must also be understood). In addition, they present information on updated Lagrangian and Eulerian formulations for the modeling of metal forming and machining. Topics covered include: Stress Strain Constitutive relations Fracture Anisotropy Contact problems Plasticity: Fundamentals and Applications enables students to understand the basic fundamentals of plasticity theory, effectively use commercial finite-element (FE) software, and eventually develop their own code. It also provides suitable reference material for mechanical/civil/aerospace engineers, material processing engineers, applied mechanics researchers, mathematicians, and other industry professionals.
