Download or read book On the Micromechanisms of Anomalous Slip in BCC Metals written by L. L. Hsiung and published by . This book was released on 2005 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dislocation substructures developed in high-purity Mo single crystals deformed under uniaxial compression at room temperature to a total strain of {approx} 0.5% with a strain rate of 1 s{sup -1} have been investigated using transmission electron microscopy (TEM) techniques in order to elucidate the underlying micromechanisms of the anomalous operation of {l_brace}0{bar 1}1{r_brace} slip systems, i.e. Schmid-law violation, in bcc metals. The crystals were oriented with the stress axis parallel to a nominal single-slip orientation of [{bar 2}920], in which the ({bar 1}01)[111] slip system is the only system having a maximum value of Schmid factor (m = 0.5). Nevertheless, the recorded stress-strain curve reveals no single-slip or easy-glide stage, and the anomalous slip occurs in both (011) and (0{bar 1}1) planes. TEM examination of the dislocation structure in the ({bar 1}01) primary slip plane reveals that in addition to the operation of the ({bar 1}01)[111] slip system, the coplanar ({bar 1}01)[1{bar 1}1] slip system that has a much smaller Schmid factor (m = 0.167) is also operative. Similarly, the (0{bar 1}1)[111] slip system (m = 0.25) is cooperative with the coplanar (0{bar 1}1)[{bar 1}11] system (m = 0.287), and the (011)[1{bar 1}1] slip system (m = 0.222) is cooperative with the coplanar (011)[11{bar 1}] system (m = 0.32). The occurrence of {l_brace}0{bar 1}1{r_brace} anomalous slip is accordingly proposed to be initiated from the cooperative dislocation multiplication and mutual trapping and blocking of 1/2[111] and 1/2[1{bar 1}1] coplanar dislocation arrays in the ({bar 1}01) plane. The resulted internal stresses render the propagation of both 1/2[111] and 1/2[1{bar 1}1] screw dislocations from the ({bar 1}01) plane onto the {l_brace}0{bar 1}1{r_brace} planes and subsequently result in the occurrence of anomalous slip.

Download or read book Dynamic Dislocation Mechanisms For the Anomalous Slip in a Single Crystal BCC Metal Oriented for Single Slip written by and published by . This book was released on 2007 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dislocation substructures of high-purity Mo single crystals deformed under uniaxial compression at room temperature to an axial strain of 0.6% were investigated in order to elucidate the underlying mechanisms for the {l_brace}0{bar 1}1{r_brace} anomalous slip in bcc metals [1], which is also known as the violation of Schmid law [2]. The test sample was oriented with the stress axis parallel to a nominal ''single-slip'' orientation of [{bar 2} 9 20], in which ({bar 1}01) [111] is the primary slip system that has a maximum Schmid factor (m = 0.5), which requires the lowest stress to operate among the twelve {l_brace}{bar 1}10{r_brace} 111 slip systems. Nevertheless, the recorded stress-strain curve reveals no easy-glide or single-slip stage; work hardening starts immediately after yielding. Moreover, the result of slip trace analysis indicates the occurrence of anomalous slip on both the (011) and (0{bar 1}1) planes, which according to the Schmid law requires relatively higher stresses to operate. TEM examinations of dislocation structures formed on the (101) primary slip plane reveal that in addition to the ({bar 1}01) [111] slip system, the coplanar ({bar 1}01) [1{bar 1}1] slip system which has a much smaller Schmid factor (m = 0.167) is also operative. Similarly, (0{bar 1}1) [111] (m = 0.25) is cooperative with the coplanar (0{bar 1}1) [{bar 1}11] slip system (m = 0.287) on the (0{bar 1}1) slip plane, and (011) [1{bar 1}1] (m = 0.222) is cooperative with the coplanar (011) [11{bar 1}] slip system (m = 0.32) on the (011) plane. The occurrence of {l_brace}0{bar 1}1{r_brace} anomalous slip is accordingly proposed to be originated from the cooperative dislocation motion of the ± 1/2 [111] and ± 1/2 [1{bar 1}1] dislocations on the ({bar 1}01) slip plane; the mutual interaction and blocking of ± 1/2 [111] and ± 1/2 [1{bar 1}1] dislocations not only cause an increase of glide resistance to the dislocation motion on the ({bar 1}01) plane but also render the ± 1/2 [111] and ± 1/2 [1{bar 1}1] screw dislocations to cross slip and propagate from the ({bar 1}01) slip plane onto the (0{bar 1}1) and (011) intersecting slip planes. That is, the ± 1/2 [111] screw dislocations cross slip from (111) onto (011), and the ± 1/2 [1{bar 1}1] screw dislocations cross slip from (111) onto (011), which subsequently render another two slip systems, (0{bar 1}1) [{bar 1}11] and (011) [11{bar 1}], to become operative. As a result, all 1/2111-type dislocations, i.e. all 111 slip, take part in the plastic deformation of the [{bar 2} 9 20]-oriented single-crystal Mo.

Download or read book On the Mechanism of Anomalous Slip in BCC Metals written by and published by . This book was released on 2011 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The mechanisms of diffusion in the anomalous bcc metals written by G. M. Hood and published by . This book was released on 1975 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Deformation Mechanisms of Some B C C Metals written by Richard Anthony Maynard and published by . This book was released on 1971 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Micromechanisms of Fracture and Fatigue written by Jaroslav Pokluda and published by Springer Science & Business Media. This book was released on 2010-05-27 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micromechanisms of Fracture and Fatigue forms the culmination of 20 years of research in the field of fatigue and fracture. It discusses a range of topics and comments on the state of the art for each. The first part is devoted to models of deformation and fracture of perfect crystals. Using various atomistic methods, the theoretical strength of solids under simple and complex loading is calculated for a wide range of elements and compounds, and compared with experimental data. The connection between the onset of local plasticity in nanoindentation tests and the ideal shear strength is analysed using a multi-scale approach. Moreover, the nature of intrinsic brittleness or ductility of perfect crystal lattices is demonstrated by the coupling of atomistic and mesoscopic approaches, and compared with brittle/ductile behaviour of engineering materials. The second part addresses extrinsic sources of fracture toughness of engineering materials, related to their microstructure and microstructurally-induced crack tortuosity. Micromechanisms of ductile fracture are also described, in relation to the fracture strain of materials. Results of multilevel modelling, including statistical aspects of microstructure, are used to explain remarkable phenomena discovered in experiments. In the third part of the book, basic micromechanisms of fatigue cracks propagation under uniaxial and multiaxial loading are discussed on the basis of the unified mesoscopic model of crack tip shielding and closure, taking both microstructure and statistical effects into account. Applications to failure analysis are also outlined, and an attempt is made to distinguish intrinsic and extrinsic sources of materials resistance to fracture. Micromechanisms of Fracture and Fatigue provides scientists, researchers and postgraduate students with not only a deep insight into basic micromechanisms of fracture behaviour of materials, but also a number of engineering applications.

Download or read book Metals Abstracts Index written by and published by . This book was released on 1978 with total page 1010 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 1994 with total page 1584 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Frontiers in Materials Science written by B. Raj and published by Universities Press. This book was released on 2005 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents contributions by a galaxy of eminent scientists and technologists from the world over in broad spectrum of areas in materials science, providing a global perspective on complex issues of current concern and the direction of research in these areas.

Download or read book A mechanism for autotwisting and the low frequency hydride precipitation peak in the bcc metals written by I. G. Ritchie and published by . This book was released on 1987 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1996 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Strengthening Mechanisms in Crystal Plasticity written by Ali Argon and published by Oxford University Press on Demand. This book was released on 2008 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technologically important metals and alloys have been strengthened throughout history by empirical means. The scientific bases of the central mechanisms of such forms of strengthening, developed over the past several decades are presented here through mechanistic models and associated experimental results.

Download or read book INIS Atomindex written by and published by . This book was released on 1985 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Wrought Magnesium Alloys written by Colleen Bettles and published by Elsevier. This book was released on 2012-04-25 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: This important book summarises the wealth of recent research on our understanding of process-property relationships in wrought magnesium alloys and the way this understanding can be used to develop a new generation of alloys for high-performance applications.After an introductory overview of current developments in wrought magnesium alloys, part one reviews fundamental aspects of deformation behaviour. These chapters are the building blocks for the optimisation of processing steps covered in part two, which discusses casting, extrusion, rolling and forging technologies. The concluding chapters cover applications of wrought magnesium alloys in automotive and biomedical engineering.With its distinguished editors, and drawing on the work of leading experts in the field, Advances in wrought magnesium alloys is a standard reference for those researching, manufacturing and using these alloys. - Summarises recent research on our understanding of process-property relationships in wrought magnesium alloys - Discusses the way this understanding can be used to develop a new generation of alloys for high-performance applications - Reviews casting, extrusion, rolling and forging technologies, fundamental aspects of deformation behaviour, and applications of wrought magnesium alloys in automotive and biomedical engineering

Download or read book The Superalloys written by Roger C. Reed and published by Cambridge University Press. This book was released on 2008-07-31 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superalloys are unique high-temperature materials used in gas turbine engines, which display excellent resistance to mechanical and chemical degradation. This book introduces the metallurgical principles which have guided their development. Suitable for graduate students and researchers, it includes exercises and additional resources at www.cambridge.org/9780521859042.

Download or read book Crystallography and Crystal Defects written by Anthony Kelly and published by John Wiley & Sons. This book was released on 2000-04-17 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crystallography and Crystal Defects Revised Edition A. Kelly, Churchill College, Cambridge, UK G. W. Groves, Exeter College, Oxford, UK and P. Kidd, Queen Mary and Westfield College, University of London, UK The concepts of crystallography are introduced here in such a way that the physical properties of crystals, including their mechanical behaviour, can be better understood and quantified. A unique approach to the treatment of crystals and their defects is taken in that the often separate disciplines of crystallography, tensor analysis, elasticity and dislocation theory are combined in such a way as to equip materials scientists with knowledge of all the basic principles required to interpret data from their experiments. This is a revised and updated version of the widely acclaimed book by Kelly and Groves that was first published nearly thirty years ago. The material remains timely and relevant and the first edition still holds an unrivalled position at the core of the teaching of crystallography and crystal defects today. Undergraduate readers will acquire a rigorous grounding, from first principles, in the crystal classes and the concept of a lattice and its defects and their descriptions using vectors. Researchers will find here all the theorems of crystal structure upon which to base their work and the equations necessary for calculating interplanar spacings, transformation of indices and manipulations involving the stereographic projection and transformations of tensors and matrices.

Download or read book Characterization of Minerals Metals and Materials 2020 written by Jian Li and published by Springer Nature. This book was released on 2020-01-23 with total page 723 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection gives broad and up-to-date results in the research and development of materials characterization and processing. Topics covered include advanced characterization methods, minerals, mechanical properties, coatings, polymers and composites, corrosion, welding, magnetic materials, and electronic materials. The book explores scientific processes to characterize materials using modern technologies, and focuses on the interrelationships and interdependence among processing, structure, properties, and performance of materials.