Download or read book Deformation Mechanisms in Tungsten Single Crystals in Ballistic Impact Experiments written by and published by . This book was released on 1993 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of tungsten single crystals in ballistic impact varies strongly as a function of crystallographic orientation. The deformation structure of recovered single crystal rods fired in ballistic environments has been characterized by optical microscopy, SEM and TEM, and x-ray diffraction. The observed microstructures are varied and provide substantial insights into the factors governing the penetration and flow behavior under ballistic conditions. Crystallographic orientation influences the potential for developing shear which enhances mat flow, and this enhancement ultimately maximizes the energy available for target penetration. Microstructural analysis elucidates the various mechanisms occuring during the flow process for single crystals of high- symmetry orientations, and suggests possible analogies between the penetration behavior of the tungsten single crystals and other materials ... Crystallography, Strain rate, Dislocations, Mass transfer, Shear stresses.
Download or read book Determination of Operable Deformation Mechanisms During Ballistic Impact in Tungsten Single Crystals Utilizing Transmission Electron Microscopy written by and published by . This book was released on 1992 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of tungsten single crystals in ballistic impact varies strongly as a function of crystallographic orientation. The deformation structure of recovered single crystal rods fired in ballistic environments has been characterized by optical microscopy, SEM and TEM, and x-ray diffraction. The observed microstructures are varied and provide substantial insights into the factors governing the penetration and flow behavior under ballistic conditions. Crystallographic orientation influences the potential for developing shear which enhances material flow, and this enhancement ultimately maximizes the energy available for target penetration. Microstructural analysis elucidates the various mechanisms occurring during the flow process for single crystals of high-symmetry orientations, and suggests possible analogies between the penetration behavior of the tungsten single crystals and other materials.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tungsten Refractory Metals and Alloys 4 1998 written by Animesh Bose and published by . This book was released on 1998 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Rate Controlling Mechanism of Plastic Deformation of Tungsten Single Crystals written by Sarat Chandra Misro and published by . This book was released on 1969 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1290 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 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plastic Deformation of Body centered Cubic Metals Volume Ii Fracture of Tungsten written by Derek Hull and published by . This book was released on 1967 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive investigation has been made of the deformation modes and fracture mechanisms in tungsten. It has been shown that high purity single crystals of tungsten are not inherently brittle but are extremely notch sensitive. Tests on pre-cracked crystals indicate that crack propagation can occur by different mechanisms depending on the testing temperature. At low temperatures where crack propagation occurs in a completely brittle manner, the fracture stress obeys a Griffith type criterion. At higher temperatures the crack extends by a slow mode of growth due to the concentration of strain energy in front of the crack tip. Prestraining at high temperatures effectively blunts the crack and increases the low temperature brittle fracture stress. The characteristic markings on the cleavage faces depend primarily on the stress level at fracture and are essentially independent of initial dislocation density and sharpenss of the microcrack. Tests on polycrystalline tungsten indicate that at temperatures below about 350 K fracture is completely brittle. At temperatures from 350 K to about 460 K the specimens yield prior to fracture but the strain to fracture is low after a region of high work hardening. At temperatures above 460 K, grain boundary parting on the specimen surface occurs immediately after yielding, resulting in increased strain to fracture. Fracture over the whole temperature range occurs predominantly by cleavage with some inter-granular separation. The amount of intergranular fracture increases slightly with temperature. Crack propagation in pre-cracked polycrystalline specimens shows similar temperature dependence to the single crystals. (Author).
Download or read book High Strain Rate Behavior of Refractory Metals and Alloys written by Minerals, Metals and Materials Society. Fall Meeting and published by Minerals, Metals, & Materials Society. This book was released on 1992 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: This aims to be the most complete volume available on the developing technology of refractory metals and alloys for high strain rate applications. Processing, testing and evaluation procedures for this group of specialized materials are thoroughly examined. Added emphasis is placed on high strain rate processing, dynamic compaction and forging, microstructure, texture, composition and loading rate effects on deformation and fracture.
Download or read book Proceedings of the 8th Pacific Rim International Conference on Advanced Materials and Processing PRICM 8 written by FernD.S. Marquis and published by Springer. This book was released on 2017-03-21 with total page 3431 pages. Available in PDF, EPUB and Kindle. Book excerpt: PRICM-8 features the most prominent and largest-scale interactions in advanced materials and processing in the Pacific Rim region. The conference is unique in its intrinsic nature and architecture which crosses many traditional discipline and cultural boundaries. This is a comprehensive collection of papers from the 15 symposia presented at this event.
Download or read book Deformation Mechanisms During Compressive Loading of Tantalum and Tantalum 2 5 Weight Tungsten written by Rajeev Kapoor and published by . This book was released on 1998 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics and Mechanics of Finite Plastic and Viscoplastic Deformation written by International Symposium on Plasticity and Its Current Applications and published by . This book was released on 1997 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dislocation Structures in Single Crystal Tungsten and Tungsten Alloys written by Joseph R. Stephens and published by . This book was released on 1969 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The High Strain Rate Deformation of Tungsten Single Crystals written by and published by . This book was released on 1994 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Samples of single-crystal tungsten, in three orientations (100, 110, 111), were compressively deformed at high strain rates (1,000-2,000 /s) using a Kolsky (split-Hopkinson) type pressure bar apparatus. Samples of the single-crystal tungsten were also deformed at low strain rate (0.0001/ s) using a conventional load frame. The 110 orientation exhibited constraint of flow consistent with twofold crystal symmetry about this axis, resulting in skewed flow and noncylindrical specimens after the Kolsky bar test. Both the 111 and 110 orientations exhibited a yield or load drop phenomenon. This load drop may have been associated with either: (1) lack of screw dislocation cross slip at high strain rate; (2) twinning of the crystal lattice; or (3)interstitial solute atoms such as nitrogen or carbon pinning dislocations. As a result of this load drop for the lower symmetry 111 and 110 orientations, the quasi-static (0.0001/s) test had higher flow stress for a given strain than the higher strain rate tests with the Kolsky bar. The 100 orientation crystals exhibited uniform deformation and high rate of work-hardening at both low and high strain rates. The unique behavior of these crystals is postulated in terms of the crystal symmetry, structural evolution at various strain rates, and dislocation flow mechanisms.
Download or read book China written by World Bank and published by World Bank Publications. This book was released on 1993 with total page 1422 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Republic of Korea's industrial policy has directed that nation's economy through nearly three decades of spectacular growth. But the authors of this paper maintain that this policy is showing signs of being outmoded. The time has come, the authors argue, for the Korean government to stop managing the economy's structural development and to redefine the responsibilities of business and government. Under this proposed compact, the allocation of resources would shift from the government to the private industrial and financial sectors. The transformation of the government bureaucracy from an ad hoc policy role to one of a transparent and predictable regulator is a key to the success of this undertaking. These new directions would present the government with enormous challenges. Greater competitive discipline and regulatory oversight would be required. While dealing with the complexities of the transition, the government would have to maintain macroeconomic stability and the momentum of savings and investment. For comparison, the study examines the industrial economies of France, Germany, Japan, and the United States, which underwent similar shifts.
Download or read book Deformation Mechanisms of Single phase TiAl Single Crystals written by Rabindranath Mahapatra and published by . This book was released on 1996 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ballistic Penetration Phenomenology of High Symmetry Single Crystals written by and published by . This book was released on 1995 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ballistic performance of tungsten single crystal penetrators is known to be a function of crystallographic symmetry. The macroscopic deformation geometry of both single crystal and polycrystal tungsten penetrators is a continuous eversion of the rod into a hollow tube. The differences in energy partitioning leading to these variations in ballistic performance must therefore be accounted for by detailed material deformation processes governed by crystallographic orientation. Inferences about these processes have been drawn from microstructural characterization of recovered penetrators. Residual penetrators of both 011 and 111 orientations were found to have repeatedly deformed and recrystalized, but the actual operative processes led to quite different macrostructures, microstructures, and penetration depths. The 001 orientation deformed by a unique process which allowed very efficient deformation, resulting in maximum penetration depth. These single crystal experiments demonstrate the critical role of detailed deformation processes in determining the final penetration depths even when similar macroscopic material flow geometry occurs. jg.
