The article is devoted to the analysis of the quality of crystallographic texture in thin tapes made of a number of Cu–40%Ni–Me (Ме=Nb, Мо, W) ternary alloys, which have the prospect of being used as epitaxial substrates. The modes of recrystallization annealing are optimized, which allow to obtain a perfect cubic texture with a grain fraction {001}<100> of more than 96% in the belts of the studied alloys with a thickness of about 100 m. The proposed alloys are paramagnetic at the operating temperature of a high-temperature superconductor and are cheaper than Nickel alloys, so they can be an alternative to the most widely used Ni–4.8 at.%W alloy in the production of tape substrates today.
By the means of metallography, scanning and transmission electron microscopy, and EBSD-analysis, the features of the structure formation upon β→α (fcc-hcp) - polymorphic transformation in Co - Nb binary alloys were studied. It was shown that upon gradual cooling of the crystallized ingot, in each β-grain of the alloy nucleation of the α-phase crystals of several orientations out of 4 possible in accordance with the Wasserman’s orientational relations occurs. The formation of any of the 4 possible orientations of the α-phase is equally probable. At room temperature, only α (hcp)-martensite was found in the structure of the studied alloys. The misorientation of the substructure in the martensitic crystals length-wise in cast alloys does not exceed 1 deg.
After the homogenization and the subsequent quenching in salted water, the structure of Co-Nb alloys does not undergo neither morphological, nor crystallographic changes, but becomes noticeably more fine-grained. In this case, the misorientation of the substructure elements of the martensitic crystals length-wise increases several times, consequent to the high level of quenching microstresses in martensite. No phases with multilayer lattices such as NR martensite were found.
Методами рентгенографии, сканирующей электронной микроскопии и микроанализа исследованы сверхпроводники MgB2, подвергнутые деформации под давлением в наковальнях Бриджмена и последующим отжигам при 800 и 950oC. Показано, что при этих температурах кристаллы фазы MgB2 вместе с остаточным бором растворяются в остаточном жидком магнии с образованием как плотных, так и рыхлых областей фазы MgB2. Последние плохо влияют на критический ток. Вместе с тем после этих обработок образцы становятся более однородными по фазовому и химическому составу. Работа выполнена по теме "Кристалл" (N г.р. 01201463333) при поддержке проектом УрО РАН N 15-17-2-16. DOI: 10.21883/FTT.2017.09.44835.076
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