185 research outputs found
Bicontinuous Isomorphisms between Two Closed Left Ideals of a Compact Dual Ring
No full textA quasi-Frobenius ring is a ring with minimum condition satisfying the conditions r(l)H)) = H and l(r(L)) = L for right ideals H and left ideals L where r(S) (l(S)) denotes the right (left) annihilator of a subset S of the ring. Nakayama first defined and studied such rings (8; 9) and they have been studied by a number of authors (2; 3; 4; 6). A dual ring is a topological ring satisfying the conditions r(l)H)) = H and l(r)H)) = L for closed right ideals H and closed left ideals L. Baer (1) and Kaplansky (7) introduced the notion of such rings, which is a natural generalization of that of quaso-Frobenius rings. Numakura studied the analogy between dual rings and quasi-Frobenius rings in (10).</jats:p
Solute–Solute Interaction In α IRON: The Status QUO
No full textAn overview is presented on the interaction of substitutional solutes with carbon and nitrogen in α iron, which is an important factor in controlling the properties of steels. Starting from a simple model of trapping of the interstitial solute atoms by substitutional solute atoms, the principles of experimental methods for quantitative studies are described, focussing on the Snoek relaxation and solubility measurements, and the knowledge acquired by such experiments is reviewed. An account of recent theoretical approaches to the interaction is also given
Wzajemne oddziaływanie atomów substytucyjnych i międzywęzłowych w żelazie alfa: status quo
No full textAn overview is presented on the interaction of substitutional solutes with carbon and nitrogen in α iron, which is an important factor in controlling the properties of steels. Starting from a simple model of trapping of the interstitial solute atoms by substitutional solute atoms, the principles of experimental methods for quantitative studies are described, focussing on the Snoek relaxation and solubility measurements, and the knowledge acquired by such experiments is reviewed. An account of recent theoretical approaches to the interaction is also given.Przedstawiono przegląd oddziaływań atomów substytucyjnych z atomami węgla i azotu w żelazie alfa, które jest ważnym czynnikiem wpływającym na właściwości stali. Zaczynając od prostego modelu pułapkowania rozpuszczonych atomów międzywęzłowych przez atomy substytucyjne, przedstawione są zasady metod eksperymentalnych stosowanych w badaniach ilościowych, koncentrując się głównie na badaniach relaksacji Snoeka i pomiarach rozpuszczalności. Przedstawiono przegląd wiedzy nabytej w takich eksperymentach oraz najnowszej próby teoretycznego opisu ww oddziaływań
Thermal crystallization of sputter-deposited amorphous Ge films: Competition of diamond cubic and hexagonal phases
No full textFollowing our previous studies on crystallization induced by electron irradiation, we have investigated the crystallization of sputter-deposited amorphous germanium films by heat treatments. On continuous heating, samples aged for 3 days and 4 months at room temperature crystallized at 500°C to form coarse spherical particles of a hexagonal structure, of about 100 nm in diameter, whereas samples aged for 7 months turned to homogeneous nanograins of the diamond cubic structure at 600°C. When the films aged for 4 months at room temperature were annealed at 350°C for 2 h and then heated, they crystallized at 550°C to form a mixture of the two microstructures, and those annealed at 350°C and further at 500°C for 1 h crystallized at 600°C mostly to nanograins. Crystallization by electron irradiation at 350°C to 4-month-aged samples has also been studied. With increasing annealing time at 350°C, coarse particles of a hexagonal structure ceased to appear, and were replaced by fine nanograins of the diamond cubic structure. These observations can be understood in terms of structural instability of sputter-deposited amorphous films. Medium-range ordered clusters must initially be present in the films and serve as nuclei of the metastable hexagonal phase. They are unstable, however, and are eliminated by annealing, resulting in the reduction in size and number of coarse particles with a metastable structure
The Snoek Relaxation in Dilute Ternary bcc Alloys. A Review
No full textThe Snoek relaxation due to interstitial solutes in bcc metals is often affected markedly by the presence of a small amount of substitutional solute atoms. This effect is believed to originate from the interaction between the substitutional and interstitial solute atoms, or the s-i interaction. This review summarizes first the experimental observations on the Snoek relaxation in various dilute alloys such as Fe-M-C/N and V/Nb/Ta-M-O/N, and describes next the theoretical studies on the thermodynamics and kinetics of the relaxation. It is suggested from recent studies that careful examinations of the variation of the spectrum with solute concentrations are useful for quantitative characterization of the s-i interaction
Dislocations in metals and alloys with the hexagonal close-packed structure
No full textAtomistic aspects of dislocations in hexagonal close-packed metals are reviewed. Computer simulation studies on the atomic structure of planar faults and dislocation cores have made essential contributions to understanding the wide variety of the plastic deformation behaviour of this class of materials. Stacking faults have been found to be the most important factor governing the core structure and the glide mechanism of dislocations; the preference for the glide plane, the magnitudes of flow stress and the deformation microstructure in various metals can be understood from the stability of the stacking faults in each material. A brief summary of the deformation behaviour of DO19 ordered alloys and intermetallic compounds is also given, focussing on Ti3Al
- …
