Strain Aging of Refractory Metals (tantalum).
Strain Aging of Refractory Metals (tantalum).

Author: W. Eliasz

Publisher:

Published: 1965

Total Pages: 111

ISBN-13:

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Strain aging effects in electron-beam refined tantalum have been studied using the yield point return and internal friction technique. The results have been discussed with reference to current theories of strain aging. A comparison of the data obtained by both techniques has been made which shows that the internal friction technique yields more direct information about the interstitial impurity responsible for the strain aging process. Electron-beam refined tantalum, when tested at room temperature, shows strain-aging effects, which become measurable at aging temperature greater than about 70 C. The activation energy of the strain-aging process has been found to be 26,000 + or - 1,000 cal/mol which is of the order of the activation energy for the diffusion of oxygen in tantalum (25,500 cal/mol). The magnitude of the strain-aging effects have been shown to be dependent on the concentration of oxygen, and this appears to be due to increased strength of pinning of dislocations with increasing oxygen content. The increase in the yield stress caused by strain-aging has been found to be no only due to the change in dislocation locking parameter, k sub y, but also to the increase in flow stress. It has been shown that in the temperature range studied (100 - 200 C) oxygen is responsible for the strain-aging effects. At higher temperatures nitrogen and/or carbon can contribute to strain-aging too. (Author).

Physical Metallurgy of Refractory Metals and Alloys
Physical Metallurgy of Refractory Metals and Alloys

Author: E. M. Savitskii

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 296

ISBN-13: 1468415727

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The principal reasons which induced the authors to write this book and the features of the book are set forth in the preface to the Russian edition. That section of the science of metals which in Russian is called "metallovedenie" or the "physical chemistry of metals" is generally referred to in scientific and technical literature published in the English language by the term "physical metallurgy." These concepts are much broader than the term" metallography," used in the scientific and technical literature of various countries, and applied solely to research on the interrelationships of the structure and proper ties of metals and alloys. Each science must have its own subject and its own method of research. Certainly, all specialists will agree that metals and alloys, including their solid solutions, mechanical mix tures, and metallic compounds, form the subject of "physical metallurgy" or "physical chemis try of metals." The aim of this science. is to produce a theory and to elucidate the experimental relationships which ought finally to make it possible to calculate quantitatively alloys Of given properties for any working conditions and parameters.

Shock Waves
Shock Waves

Author: W. M. Isbell

Publisher: Imperial College Press

Published: 2005

Total Pages: 344

ISBN-13: 186094471X

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This book presents, in a concise and comprehensive manner, the essential techniques by which shock wave physicists probe the boundaries of material response to impulsive loads. The author is a well-known figure in shock wave physics, having worked for over forty years with many of the outstanding researchers in the field.The book acquaints readers both with modern instrumentation techniques including interferometers such as the DISAR and the VISAR ? and with methods that have been established by previous generations of experimentalists ? including acoustic measurement techniques and low to moderate strain rate machines.Besides an exposition of the theoretical aspects of shock wave phenomena, it contains large amounts of data on equations of state, spallation thresholds, shock wave attenuation from very high pressures, and elastic constants. Much of this information has been previously unavailable in open publications.The text documents the transition from testing performed with explosives to the use of modern compressed gas guns, which permit much more detailed diagnostics and controlled conditions. In particular, the author pioneered the use of two-stage light gas guns which launch high-density plates against specimens located at the muzzle. The high launch velocity of these guns produced data that represents the highest pressures obtained in the free world at that time.