A part of the shock-waves science and technology has stimulated the research field of “Materials Dynamics” which needs some technological evolution for the diagnostics of ultra fast phenomena and some conceptual evolution for the hierarchy of the material domain dependent on sound speed. This article describes fundamental features of shock-waves science and gives some examples of diagnostic technologies such as pump and probe measurements for time-resolved x-ray diffraction and Raman scattering under shock loading.
Recent results from shock-induced phase transitions and molecular structure changes are reviewed and compared with those obtained by static high pressures and by first-principles simulations. This illustrates the unique conditions shock waves generate in terms of chemistry and physics.
This report describes studies on gas-gun-based or pulse laser-induced shock waves in condensed materials with relatively high compressibility like polymers and bio-related materials. We have studied phenomena of the pressure range less than several GPa. Topics covered include (i) development of precision shock Hugoniot measurement methods developed for the present pressure region, (ii) discussion of several experimental results and (iii) some applications to medicine and initiation of high explosive charge.
Shock compression can be used to consolidate a nonequilibrium alloy or compound powders without recrystallizing or decomposition, taking advantage of the high pressure and short duration, in addition it can be used to synthesize high-pressure phases. Mechanical alloying (MA) has also recently been used for nonequilibrium materials processing, including the preparation of metastable solid solution phases, amorphous phases, nano crystals, etc. We have been preparing nonequilibrium bulk materials consisting of such metastable phases in the transition metal systems or tungsten systems, etc. by using shock compression, and investigating the physical properties. Particularly, the metastable solid solution bulk alloys in transition metal systems showed interesting magnetic properties in relation to the Slater-Poring curve. In addition, a fully-dense Sm2Fe17Nx magnet was for the first time prepared. In this review, the topical magnetic properties of these metastable alloys (Fe-Co, Fe-Cu, Fe-W) and the Sm-Fe-N magnet are shown.
High pressure apparatuses are now only moderately expensive, and can be employed, usefully and without much extra effort, in a much wider context than that originally envisaged. This article deals with the recent developments made in such fields as 1) the Diels-Alder reaction, 2) the synthesis of natural products employing Diels-Alder strategy, 3) ionic reactions.
In the early days of nuclear science, many researchers tried to see if a nuclear decay constant could be changed by putting radioactive nuclei in various extreme environments, such as high and low temperatures, high pressure and high electromagnetic fields. They could not find any measurable change. Since then it was believed that a nuclear decay constant was independent of extranuclear conditions. In 1947, it was pointed out that there might be observable changes in decay constants when decay modes were dominated by an electron capture or an internal conversion process. Thereafter, many experimental studies were carried out, and their changes were observed. We studied the change of the decay constant of 99mTc by applying high-pressure. The present status of our study is described in this report.
The development of autoclaves for high resolution NMR at elevated pressures is briefly reviewed. NMR data on simple supercritical fluids and their binary mixtures are discussed. The emphasis in the substance selection is on simple fluids that may serve as model compounds for the test of models of molecular dynamics in liquids and on substances that have found technical application in fluid extraction and as solvents for supercritical synthesis.
Recently, a lot of work has been performed to put supercritical water processes to practical use. Especially, supercritical water oxidation (SCWO) is an efficient procedure for rapid and complete destruction of organic compounds. However, corrosion of the materials of fabrication is a serious concern. The current data base suggests that iron-base and nickel-base alloys are not likely to be capable of handling conditions associated with aggressive SCWO streams. Titanium alloys are recommended for severe SCWO service applications.