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[en] Highlights: • Effects of the Li addition on long period stacking ordered structures were investigated. • Extrusion speed and die angle should be emphatically considered. • High strength and ductility Mg89Y4Zn2Li5 alloy was obtained. • Excellent performance due to deformed long period stacking ordered structures and fine dynamical recrystallized grains. The effects of the Li addition on the microstructure evolution of Mg94-xY4Zn2Lix (at.%, x = 0, 1, 5, 9 and 13) alloys were systematically investigated. Little Li ( 1 at.%) addition inhibited the precipitation of 18R LPSO phases. While the (Mg, Zn)24Y5 eutectic phases increased gradually with the addition of Li. Microstructural refinement was significant when the content of Li was 5 at.%. Li addition also changed the formation behavior of 14H LPSO phase of solid-solution Mg89Y4Zn2Li5 alloy only containing α-Mg and LPSO phases. The ultimate tensile strength and elongation of as-extruded Mg89Y4Zn2Li5 alloy reached to 385 MPa and 14%, respectively. The coexistence of kinky block 18R LPSO phases and fine dynamical recrystallized (DRXed) grains surrounding bent lamellar 14H LPSO phases was responsible for the excellent mechanical properties.
[en] Current carrying capacity is one of the most important issues in the consideration of superconductor bulk materials for engineering applications. There are numerous applications of Y-Ba-Cu-O (YBCO) bulk superconductors e.g. magnetic levitation train, flywheel energy storage system, levitation transportation, lunar telescope, centrifugal device, magnetic shielding materials, bulk magnets etc. Accordingly, to obtain YBCO materials in the form of large, single crystals without weak-link problem is necessary. A top seeded melt growth (TSMG) process was used to fabricate single crystal YBCO bulk superconductors. The seeded and infiltration growth (IG) technique was also very promising method for the synthesis of large, single-grain YBCO bulk superconductors with good superconducting properties. 5 wt.% Ag doped Y211 green compacts were sintered at 900 .deg. C ∼ 1200 .deg.C and then a single crystal YBCO was fabricated by an infiltration method. A refinement and uniform distribution of the Y211 particles in the Y123 matrix were achieved by sintering the Ag-doped samples. This enhancement of the critical current density was ascribable to a fine dispersion of the Y211 particles, a low porosity and the presence of Ag particles. In addition, we have designed and manufactured large YBCO single domain with levitation force of 10-13 kg/cm2 using TSMG processing technique
[en] We present results of Raman spectroscopic studies of superconducting YBa2Cu3O7 (YBCO) coated conductors. Raman scattering is used to characterize optical phonon modes, oxygen content, c-axis misalignment, and second phases of the YBCO coated conductors at a micro scale. A two-dimensional mapping of Raman spectra with transport properties has been performed to elucidate the effect of local propertied on current path and superconducting phase. The information taken from the local measurement will be useful for optimizing the process condition.
[en] A high strength, light weight ''in-situ'' Ti-Y composite is produced by deformation processing a cast body having Ti and Y phase components distributed therein. The composite comprises elongated, ribbon-shaped Ti and Y phase components aligned along an axis of the deformed body
[en] The hot tearing susceptibility (HTS) and its mechanism of Mg-4.5Zn-xY-yNd (x + y = 6, x = 0, 1, 3, 6) alloys is studied based on Clyne-Davies’ model and ‘T’ mold. The hot tearing tendency of four alloys is characterized by SEM, XRD and TEM. Morever, HTS of four kinds of Mg-4.5Zn-xY-yNd alloys is predicted by numerical simulation (ProCAST). The order of the four alloys arranged according to HTS from high to low is as follows: Mg-4.5Zn-3Y-3Nd > Mg-4.5Zn-1Y-5Nd > Mg-4.5Zn-6Nd > Mg-4.5Zn-6Y. The results show that the crystalline state of α-Mg phase and the type of the second phase change with the relative contents of Y and Nd, which are the main factors determining the hot tearing tendency. For Mg-4.5Zn-6Y alloy, the main precipitated phases are LPSO phase (Mg12ZnY) and W phase (Mg3Zn3Y2). For Mg-4.5Zn-3Y-3Nd and Mg-4.5Zn-1Y-5Nd alloys, the main precipitates are W phase (Mg3Zn3(Y, Nd)2). For Mg-4.5Zn-6Nd alloy, the main precipitation phase is only T phase (Mg-Zn-Nd ternary phase). (paper)
[en] Saturation magnetization measurements were made on Y/sub 1 - x/Th/sub x/Fe3 compounds up to a field of 120 kOe. The moment decreases linearly with x. The results on fine particles of Y0.1Th0.9Fe3 indicate that the anomaly observed in this material does not arise due to the magnetic anisotropy
[en] The effect of experimental variables such as pack coating temperature and time concentration of yttrium and activators on the formation of coating layers of pack coated Ni-based superalloys together with the oxidation behavior of these alloys has been investigated using EPMA, and SEM. Generally, sound coating layer were obtained by pack coating at 1373K with the use of NaCl activator. The concentration of yttrium in the coating layer depends upon the concentration of yttrium in pack reagents, activators and concentration of aluminium in the substrate alloy. More dense coating layers were formed with the increasing of yttrium concentration in pack reagent. Sound coating layers were formed at high concentration of yttrium in pack reagents for a short treating time, on case of MA6000 alloy. While sound coating layers were formed at low concentration of yttrium in pack reagents for a relatively long treating time in case of MA754 alloy of which aluminium concentration is very low
[en] Itinerant electron metamagnetism was studied by ultra-high field magnetization for the system Y(Co1-xNix)3 (x=0∝0.1). The metamagnetic transition fields were observed to increase with increasing the number of 3d electrons. This is attributed to the decrease in the exchange field acting on the 3d moment. (orig.)