Book Description
L'objectif de cette étude est de comprendre les mécanismes de déformation dans les monocristaux de LiF et MgO associés aux premiers stades de plasticité induits sous nanoindentation. Pour ce faire, une nouvelle technique (nanoetching) basée sur la combinaison de l'attaque chimique, du polissage mécano-chimique contrôlé et sur des observations par AFM, a été développée pour observer les structures de dislocations en trois dimensions autour d'empreintes. Cette technique a notamment permis d'identifier clairement les différentes dislocations mises en jeu (vecteurs de Burgers, plans de glissement) ainsi que leur interactions mais également d'examiner avec un œil nouveau leur processus de nucléation, spécialement pendant la transition élastique - élasto-plastique. Enfin certaines de ces structures, particulièrement simples, ont pu être modélisées à partir de l'expression du champ de contraintes créé autour d'un indenteur sphérique. La première partie de ce travail est consacrée à une revue bibliographique des principaux modèles de déformation mis en jeu en nanoindentation. Les deux chapitres suivants présentent les techniques expérimentales mises en œuvre dans cette étude. En particulier, la technique de nanoetching dans toute sa phase d'élaboration est détaillée dans la partie 3. Le chapitre 4 est quant à lui dédié à l'étude des mécanismes de déformation mis en jeu durant le stade élasto-plastique. En particulier, les déformations de surface associées à l'essai d'indentation y sont interprétées en termes de mécanismes d'interaction dislocationnels. Les chapitres 5 et 6 sont consacrés à la modélisation des phénomènes initiant la plasticité dans MgO (pop-in). Un modèle élastique simple, basé sur un critère de nucléation déterminé expérimentalement, a permis de montrer que la transition élastique - élasto-plastique pouvait être attribuée à une délocalisation du site de nucléation des dislocations.
Author: Peter Lagerlof Publisher: MDPI ISBN: 303897465X Category : Languages : en Pages : 317
Book Description
This book is a printed edition of the Special Issue "Crystal Dislocations: Their Impact on Physical Properties of Crystals" that was published in Crystals
Author: I. Kovács Publisher: Elsevier ISBN: 1483146189 Category : Science Languages : en Pages : 359
Book Description
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.
Author: Jaap Schijve Publisher: Springer ISBN: 3319236067 Category : Technology & Engineering Languages : en Pages : 30
Book Description
Problems of fatigue under multiaxial fatigue loads have been addressed in a very large number of research publications. The present publication is primarily a survey of biaxial fatigue under constant amplitude loading on metal specimens. It starts with the physical understanding of the fatigue phenomenon under biaxial fatigue loads. Various types of proportional and non-proportional biaxial fatigue loads and biaxial stress distributions in a material are specified. Attention is paid to the fatigue limit, crack nucleation, initial micro crack growth and subsequent macro-crack in different modes of crack growth. The interference between the upper and lower surfaces of a fatigue crack is discussed. Possibilities for predictions of biaxial fatigue properties are analysed with reference to the similarity concept. The significance of the present understanding for structural design problems is considered. The book is completed with a summary of major observations.
Author: International Atomic Energy Agency Publisher: ISBN: 9789201080202 Category : Languages : en Pages : 218
Book Description
This publication is the result of an IAEA technical meeting and reports on Member States' capabilities in modelling, predicting and improving their understanding of the behaviour of nuclear fuel under accident conditions. The main results and outcomes of a coordinated research project (CRP) on this topic are also presented.
Author: Henri Bailly Publisher: Lavoisier ISBN: 9781898298571 Category : Science Languages : en Pages : 642
Book Description
This text discusses the design, manufacture and behaviour of nuclear fuel in pressurized water reactors (PWR) and fast reactors (FR). It reflects the knowledge of the French Agency for Nuclear Power (CEA) and other specialized companies in the field.
Author: Paolo Beccarelli Publisher: Springer ISBN: 3319022288 Category : Technology & Engineering Languages : en Pages : 146
Book Description
This book offers a well-structured, critical review of current design practice for tensioned membrane structures, including a detailed analysis of the experimental data required and critical issues relating to the lack of a set of design codes and testing procedures. The technical requirements for biaxial testing equipment are analyzed in detail, and aspects that need to be considered when developing biaxial testing procedures are emphasized. The analysis is supported by the results of a round-robin exercise comparing biaxial testing machines that involved four of the main research laboratories in the field. The biaxial testing devices and procedures presently used in Europe are extensively discussed, and information is provided on the design and implementation of a biaxial testing rig for architectural fabrics at Politecnico di Milano, which represents a benchmark in the field. The significance of the most recent developments in biaxial testing is also explored.
Author: Lars Arnberg Publisher: ISBN: 9783038356400 Category : Liquid alloys Languages : en Pages : 0
Book Description
The research on metals in their liquid state has been underestimated for a long time and the specific literature was scarce compared to those regarding solid metals. In the last twenty years, the situation has progressively changed and the matter has emerged as a fundamental area of investigation for physicists, metallurgists and materials scientists with consequent achievement of relevant results both on basic and applicative aspects. Today the description and the characterisation of molten metals and alloys is a wide and interdisciplinary topic and involves different approaches, from physics to technology, from processing to modelling.The book is structured in review and research papers and offers the state-of-the-art information on physics, technological properties, processing and modelling of physical and technological behaviour of liquid metals and alloys
Author: International Atomic Energy Agency Publisher: IAEA ISBN: Category : Business & Economics Languages : en Pages : 100
Book Description
The reactors around the world have produced more than 2000 tonnes of plutonium, contained in spent fuel or as separated forms through reprocessing. Disposition of fissile materials has become a primary concern of nuclear non-proliferation efforts worldwide. There is a significant interest in IAEA Member States to develop proliferation resistant nuclear fuel cycles for incineration of plutonium such as inert matrix fuels (IMFs). This publication reviews the status of potential IMF candidates and describes several identified candidate materials for both fast and thermal reactors: MgO, ZrO2, SiC, Zr alloy, SiAl, ZrN; some of these have undergone test irradiations and post irradiation examination. Also discussed are modelling of IMF fuel performance and safety analysis. System studies have identified strategies for both implementation of IMF fuel as homogeneous or heterogeneous phases, as assemblies or core loadings and in existing reactors in the shorter term, as well as in new reactors in the longer term.
Author: Yves Gaillard (physicien).)
Author: Peter Lagerlof
Author: I. Kovács
Author: Jaap Schijve
Author: International Atomic Energy Agency
Author: Henri Bailly
Author: Paolo Beccarelli
Author: R. J. Arsenault
Author: Lars Arnberg
Author: International Atomic Energy Agency