Features of shear transformation texture in seamless pipes

Microstructure and texture in seamless 0.08C-Cr-Mo-V, 0.25C-Cr-Mo-V-Nb, 0.08-13Cr-3Ni-Mo-V-Nb, and 18Cr-9Ni steel pipes are studied in the as-rolled and heat-treated states using orientation EBSD microscopy. It has been found that all types of microstructure (ferrite, martensite, and bainite) in products, both after hot rolling and after heat treatment, have well-defined axial crystallographic texture, where the direction is predominately perpendicular to the pipe surface. It is demonstrated that texture formation in heat-treated states is inherited due to the following factors important for the rules of orientation selection during the γ→α phase transformation: 1) occurrence of stable orientation of austenite grains resulted from straining; 2) special misorientation (boundaries) of austenite grains where transformation starts; 3) orientation relationships known for phase transformation; 4) thermal stresses in a product, formed during cooling. The latter can be considered as factor determining special texture in seamless steel pipes. © 2018 Author(s)

Alpha Channeling in a Rotating Plasma

The wave-particle alpha-channeling effect is generalized to include rotating plasma. Specifically, radio frequency waves can resonate with alpha particles in a mirror machine with ExB rotation to diffuse the alpha particles along constrained paths in phase space. Of major interest is that the alpha-particle energy, in addition to amplifying the RF waves, can directly enhance the rotation energy which in turn provides additional plasma confinement in centrifugal fusion reactors. An ancillary benefit is the rapid removal of alpha particles, which increases the fusion reactivity.Comment: 4 pages and 3 figure

Crystallography of Recrystallization in Al and Cu with Fiber Texture

The interest in the crystallography of structural transformations is driven by emerging capabilities in texture control and by the resulting anisotropy of the physical-mechanical properties of functional materials and products. The recrystallization texture of cold-drawn Cu and Al samples after recrystallization annealing at different temperatures was studied using EBSD. Equivalent deformation textures of Al and Cu are transformed into different recrystallization textures. The recrystallization nuclei in Al are formed at high-angle boundaries between deformed grains close to Σ3 CSL boundaries. The recrystallization nuclei in Cu are formed inside the deformed grains at twin boundaries (Σ3). The recrystallization nuclei in both Al and Cu are the crystallites whose boundaries approximately correspond to misorientation rotated about the axis at an angle of 52–70° from a deformed matrix. The physical interpretation of the results will allow for the development of new models and the enhancement of existing models of texture inheritance. © 2023 by the authors.Ministry of Education and Science of the Russian Federation, MinobrnaukaThis research was funded by the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program)

ОСОБЕННОСТИ СТРУКТУРЫ ЛИГАТУРНЫХ СПЛАВОВ Al–Hf–Sc

The microstructure peculiarities of the new Al–Hf–Sc master alloys were studied using the methods of optical and scanning electronic (SEM) microscopy in combination with EDX analysis. The alloys studied included the meta-stable intermetallic compounds (aluminides) having cubic lattices identical to those in the matrix of aluminum alloys. Binary and ternary alloys were melted in graphite crucibles at a carbon-resistance furnace under an argon atmosphere. Al–0,96at.%Hf (5,98 wt.% Hf) and Al–0,59at.%Hf (3,77 wt.% Hf) alloys were prepared by superheating above the melting point up to about 200 and 400 degrees respectively. Melts were poured into a bronze casting form where crystallization rate was ~103 degrees/sec. Besides stable aluminides with tetragonal lattices, Al3Hf metastable aluminides with cubic lattices were formed only in the melt superheated by 400 degrees above the melting point. The degree of superheat for ternary alloys where Aln(Hf1–xScx) meta-stable aluminides were formed was 240, 270 and 370 degrees. The hafnium fraction in the Aln(Hf1–xScx) aluminides changed from 0,46 to 0,71 depending on the Hf : Sc ratio in the alloy. The master alloys produced (at.%): Al–0,26Hf–0,29Sc and Al–0,11Hf–0,25Sc (wt.%: Al–1,70Hf–0,47Sc and Al–0,75Hf–0,42Sc) demonstrate fine grain structures with meta-stable aluminides of Aln(Hf0,58Sc0,42) and Aln(Hf0,46Sc0,54) compositions respectively. Aluminide sizes are less than 12 and 7 μm. Their crystal lattice mismatch with the aluminum alloy matrix lattice is less than for Al3Sc. This fact allows us to expect high modifying effects of the experimental Al–Hf–Sc master alloys in their further application. In addition, replacement of expensive scandium with hafnium in the master alloys can reduce scandium consumption considerably.С использованием методов оптической и электронной сканирующей микроскопии, рентгеноспектрального микроанализа изучены особенности микроструктуры новых лигатурных сплавов системы Al–Hf–Sc с метастабильными алюминидами, имеющими кубическую решетку, идентичную решетке матрицы алюминиевых сплавов. Выплавку бинарных и тройных сплавов проводили в печи угольного сопротивления в графитовых тиглях в атмосфере аргона. Сплавы Al–0,96ат.%Hf (5,98 мас.% Hf) и Al–0,59ат.%Hf (3,77 мас.% Hf) готовили при перегреве над температурой ликвидуса около 200 и 400 град соответственно. Расплавы заливали в бронзовую изложницу, скорость кристаллизации в которой составляла ~103 град/с. Только в сплаве, перегретом над температурой ликвидуса на 400 град, наряду со стабильными алюминидами с тетрагональной решеткой образовались метастабильные алюминиды Al3Hf с кубической решеткой. Перегрев тройных расплавов, в которых сформировались метастабильные алюминиды Aln(Hf1–xScx), составил 240, 270 и 370 град. В зависимости от соотношения Hf и Sc в сплаве доля гафния в алюминидах Aln(Hf1–xScx) изменяется от 0,46 до 0,71. Лигатурные сплавы (ат.%) Al–0,26Hf–0,29Sc и Al–0,11Hf–0,25Sc (мас.%: Al–1,70Hf–0,47Sc и Al–0,75Hf–0,42Sc) характеризуются тонкой структурой зерна и метастабильными алюминидами состава Aln(Hf0,58Sc0,42) и Aln(Hf0,46Sc0,54) соответственно. Размеры алюминидов не превышают 12 и 7 мкм. Несоответствие их решеток с решеткой матрицы алюминиевых сплавов меньше, чем таковое для Al3Sc. Это позволяет предположить проявление опытными лигатурами Al–Hf–Sc высокого модифицирующего эффекта при их дальнейшем использовании. Кроме того, замещение гафнием дорогостоящего скандия в лигатурных сплавах может значительно сократить расход последнего

Fano resonances in plasmonic core-shell particles and the Purcell effect

Despite a long history, light scattering by particles with size comparable with the light wavelength still unveils surprising optical phenomena, and many of them are related to the Fano effect. Originally described in the context of atomic physics, the Fano resonance in light scattering arises from the interference between a narrow subradiant mode and a spectrally broad radiation line. Here, we present an overview of Fano resonances in coated spherical scatterers within the framework of the Lorenz-Mie theory. We briefly introduce the concept of conventional and unconventional Fano resonances in light scattering. These resonances are associated with the interference between electromagnetic modes excited in the particle with different or the same multipole moment, respectively. In addition, we investigate the modification of the spontaneous-emission rate of an optical emitter at the presence of a plasmonic nanoshell. This modification of decay rate due to electromagnetic environment is referred to as the Purcell effect. We analytically show that the Purcell factor related to a dipole emitter oriented orthogonal or tangential to the spherical surface can exhibit Fano or Lorentzian line shapes in the near field, respectively.Comment: 28 pages, 10 figures; invited book chapter to appear in "Fano Resonances in Optics and Microwaves: Physics and Application", Springer Series in Optical Sciences (2018), edited by E. O. Kamenetskii, A. Sadreev, and A. Miroshnichenk