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The dynamic recrystallization behavior of as-cast Ti-46.5Al-3Ta-2Cr-0.2W alloy during isothermal compression process with nominal deformation of 50% and strain rates from 0.01s to 1s was investigated by electron microscopy. The results showed that the deformation mechanism of this alloy can be concluded as grain boundary sliding and mechanical twins, which induce the final dynamic recrystallization. The phase boundary bulging was found to be the major nucleation mechanism responsible for the lamellar globularization and the formation of recrystallized γ grains inside the lamellar colony under the high strain rate. The recrystallized γ grains induced by the twinning is the main mechanism for refining α2 lamellar microstructures under low strain rate.

Monotonically decreasing sequence data for the traditional modeling method using the gray model accuracy is not high , and GM (1, 1) modeling method has inherent deviation , Model does not meet the compatibility condition, using Accumulated Generating Operation in reciprocal number ,make best use of last information and GM (1, 1) modeling , is deduced and the parameters optimization grey derivative calculation formula ,and then established GRM(1,1) based on accumulated generating operation in reciprocal number on the equidistance, Gray provides a new method of modeling . Data processing examples show that the model's practicality and reliability.

Summary Type XI collagen is a fibrillary collagen. Type XI collagen is broadly distributed in articular cartilage, testis, trachea, tendons, trabecular bone, skeletal muscle, placenta, lung, and the neoepithelium of the brain. Type XI collagen is able to regulate fibrillogenesis by maintaining the spacing and diameter of type II collagen fibrils, and a nucleator for the fibrillogenesis of collagen types I and II. Mutations in type XI collagen are associated with Stickler syndrome, Marshall syndrome, fibrochondrogenesis, otospondylomegaepiphyseal dysplasia deafness, and Weissenbacher–Zweymuller syndrome. Type XI collagen binds heparin, heparan sulfate, and dermatan sulfate. Currently there are no biomarkers for type XI collagen.

Transgenic tomato plants were produced with the isopentenyl transferase gene (ipt) ligated to a promoter that is active exclusively in sink tissue. Initially, transgenic plants had smaller, round-scale leaves, swollen stems, and exhibited early development of lateral shoots compared to wild type. Expression of the ipt gene resulted in the formation of unbranched roots on cuttings and delayed senescence in excised leaves. Callus and root formation occurred on excised leaves and leaf discs during dark incubation. The retention percentage of chlorophyll, as well as cytokinin in excised leaves or discs was significantly greater than wild type. Transgenic tomato fruit had elevated levels of cytokinins in the first days after fruit set and these levels were maintained longer during fruit development.

It is reported that Ca-doping can improve the weak links between grain boundaries and increase the critical current density J c of YBa 2 Cu 3 O 7− δ polycrystalline films [Phys. Rev. B 58 (1998) 9543; Nature 407 (2000) 162]. In this paper, we investigated the preparation and superconducting properties of YBa 2 Cu 3 O 7− δ (YBCO) and Y 1− x Ca x Ba 2 Cu 3 O 7− δ ( x = 0.05, 0.1, and 0.2) (YCBCO) coatings on yttrium stabilized zirconia (YSZ) single crystal substrates by powder melting growth process. The X-ray diffraction (XRD) indicated that: (1) the coatings were of YBa 2 Cu 3 O 7− δ (Y123) phase with c -orientation; (2) the Y 2 BaCuO 5 (Y211) phase remained clearly in the YBCO coating, but much less in the YCBCO coatings. The effect of Ca-doping on the formation of the Y211 phase was analyzed with the help of the differential thermal analysis (DTA). The results of R – T and I – V relationship at 77 K demonstrated that the zero resistance temperature T c0 decreased with the Ca content, while the critical current density J c (77 K) was improved for x = 0.05.

The microstructure of annealed Ti 50 Ni 24.9 Cu 25 Y 0.1 alloy was studied through X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. It has been shown that the microstructure was composed of the B19 martensite. The temperature, frequency and strain amplitude dependences of the internal friction (IF) in the Ti 50 Ni 24.9 Cu 25 Y 0.1 alloy were investigated by dynamic mechanical analyzer (DMA), as well as differential scanning calorimetry (DSC) measurement. The DSC results indicated that only a stage of the phase transformation took place and yttrium (Y) solid-solution narrowed the transformation hysteresis. The IF kept a high value in the stage of martensitic phase and the phase transformation due to the addition of Y element during nonisothermal process. The isothermal internal friction curves were observed in our work.

We prepared precursors with fine BaZrO3 inclusions for melt-texture growth of high-temperature superconductors with nominal composition of Y1.5Ba2Cu3Oy + x BaZrO3 (x = 0, 0.04, 0.08, and 0.1), by the process of liquid-phase powder melt-texture growth (LPMG). We then investigated the effects of the precursors on the texture growth and the microstructure of composite YBa2Cu3O7-δ/Y2BaCuO5 (YBCO). The BaZrO3 particles were about 100 nm in size in the textured YBa2Cu3O7-δ (Y123), observed by the scanning electron microscopy (SEM). Owing to the pushing effects of growing fronts, fine particles were pushed out of and thus gathered in front of the growing fronts or between Y123 grains. The gathered particles in turn blocked the further growth of the Y123 grains. However, BaZrO3 particles seeded Y123 grains, giving rise to multigrain growths. These negative effects of BaZrO3 fine particles exclude themselves as effective flux pinning centers in the textured YBCO.

Ultrafine SnO 2 powder was made with grain size down to 20 nm. Such powder was introduced into the textured growth of Y 1+ x Ba 2 Cu 3 O 7+ δ (YBCO) superconductors. Crystalline inclusions, which were cubic in shape and from micrometer to submicrometer in size, were found trapped inside such grown YBCO superconductors. Determined by energy dispersive spectroscopy (EDS), and further confirmed by X-ray diffraction, the composition of the inclusions was Y 2 Ba 5 (Sn 3− y − z Cu y Pt z )O x . This Sn-based phase belongs to double perovskite structures. They were not trapped uniformly inside the YBa 2 Cu 3 O 7− δ (123), possibly caused by the agglomeration of the SnO 2 powder at the very beginning. Nevertheless, it is possible for fine Sn-based inclusions down to a few hundred nanometers to be trapped inside the 123. The addition of the ultrafine SnO 2 to YBCO textured superconductors without Pt did not seem to affect the size of Y 2 BaCuO 5 (211) particles. For comparison, Y 2 Sn 2 O 7 was also introduced to YBCO textured superconductor. In this case, the so-called φ phase YBa 3 Sn 2− x Cu x O 9− δ was found.

The off-diagonal Seebeck effect was investigated on a melt-textured YBa2Cu3O7−δ (YBCO) high-Tc superconductor. It was found that the transverse voltage Vx was proportional to the longitudinal temperature difference Δ Tz, measured directly with a pair of differential thermocouples, for textured samples with their c-axes tilted with respect to the surface’s normal. This supported the idea that the off-diagonal thermoelectric effect accounts for the anomalously high laser-induced transverse voltage on the oriented YBCO superconducting thin films. The variation of the Vx against the sample’s thickness d, at a given Δ Tz, deviated from the inversely proportional relationship when the sample was too thin. The deviation was discussed qualitatively in terms of deteriorated surface layers. The data of Vx(d) was fitted to obtain a reasonably reliable ∣ Sc−Sab∣ value of 12 μ V K−1.

Both the off-diagonal Seebeck effect and the off-diagonal Peltier effect were investigated on the same textured sample YBa2Cu3O7−δ and with the use of the same experimental setup. The effectiveness of several kinds of heat-conductive media was studied for the measurement. The flatness of both the sample and the heat-conducting block, and the matching between them were found very important for the reduction of the heat resistance of the interfaces. A reasonable agreement was found between the off-diagonal Seebeck coefficient measured by the off-diagonal Seebeck effect and that by the off-diagonal Peltier effect. The steplike feature in the relation between the off-diagonal Seebeck coefficient and the annealing temperature may imply a nonmonotonous change of the Seebeck coefficient along the c axis (Sc) with oxygen content.

We report a simple and safe technology where rather pure Hg-1201 phase superconducting bulk samples can be fabricated. The pellet was heated at about 700°C for only 30 min in open air under atmospheric pressure. We have found that a dehydration process (heating for 20 h at 250°C) is a crucial procedure for success in forming the Hg-1201 phase.

We have discovered that SrO is a good ‘intervening substrate’, in a melt-textured-growth (MTG) process, to be placed between the bulk sample and crucible to minimize loss of sample mass due to diffusion. The fractured surfaces of the subsequent MTG bulk sample show highly oriented layers a few μm thick in regions on a scale of ≈ 100 μm. Some of the layers were found to be composed of further thinner parallel layers of ≈ 0.2 μm. Transmission electron microscopy observation reveals that fringes representing the c axis of the aligned 2223 crystals appear in many of our film samples of thickness ≈ 70–80 nm. Tangles of dislocations, tweed structure and crosshatched lattice fringes were discovered. Although a very slow cooling rate of 0.5 °C h−1 was used during the crystal formation period, lattice fringes of various directions and structures show up on 100 nm-100 A scales. The difference between the microstructure of the Bi specimen and that of the Y-class samples is discussed.

We have used Y 2 Sn 2 O 7 powders in preparing the Sn-doped YBCO sample materials in order to supply oxygen internally during the crystal growth process. The better samples, which show high proportions of microdefects, allow bulk critical current > 3 × 10 4 A cm −2 . We analyze the microdefects on a scale from 30 μm – 100 A of the melt-textured growth (MTG) samples with our SEM and 200 kV TEM. Clear bright and dark interference lines of thickness ≈ 3 A appear in our micrographs. These quasi-parallel lines, which represent structural features of atomic layers, indicate that many dislocations, twin boundaries and stacking faults appear in the MTG sample. Atomic layers appear to “add in” the Y-123 crystal growth.

Making use of the non-zero spatial temperature gradient at certain locations of a common tube furnace, we have fabricated bulk rectangular samples with nominal compositions YBa 2 Cu 3− x Sn x O 7−δ with highly oriented single crystal-like layers. The temperature range of 1028-930°C is believed to be a crucial period during which single crystal-like layers are formed in the MTG process and our report is based on samples prepared with a cooling rate of 5°C/h in the stated range. We have also carried out detailed energy dispersive X-ray spectroscopy analysis along a number of crystal layers, obtaining atomic percentages along these layers. With simple, plausible assumptions, we have found the phase amounts along the crystal layers. The process of analysis is repeated for the loose grains occurring in between the layers. Generally speaking, the amount of Y-123 present in the layers is around 50%-75%. The DC magnetization loops of these samples were also measured giving us very encouraging J c values of about 3.0 × 10 4 A cm −2 .

We fabricated a new type of superconducting ceramic satisfying the stoichiometric ratio of YTe x Ba 4 Cu 6 O y with x ranging from 0 to 0.8, using compounds CuTeO 3 , Y 2 O 3 , BaCO 3 and CuO. The T c ( R = 0) values of these superconductors are found to fall in the 89–94 K range. When x = 0.72, the critical current density J c is found to be enhanced about 7 times compared to that of the YBa 4 Cu 6 O y (or the common YBa 2 Cu 3 O 7−δ ) ceramic. The lower and upper limits of J c measured and estimated for the best sample reach values of 1250 Acm −2 and over 10 4 Acm −2 , respectively. X-ray and SEM analyses indicate clearly that these new superconductors have crystal structures very much different from that of the well-known Y-123 specimen. In particular, we found that the nominal YBa 4 Cu 6 O y ceramic is made up of a dominant structure YBa 4 Cu 5 O 11−δ plus a small amount of the common 123 phase. The crystal lattice constants of this 145 new phase are roughly estimated to be: a = 5.240 A , b = 5.827 A , c = 11.507 A . When T c , is mixed in, the mechanical hardness of the resulting ceramic is much enhanced.

The MgO ultrafine powder was prepared by the common Sol-Gel process. Determined by the line width at half-height of powder X-ray diffraction, the MgO powder was about 20nm in size on average. A supersonic vibration was introduced to destroy the accumulation of the ultrafine powder and to mix the powder with the YBa2Cu3O7-δ precursor. The melt-process was employed to grow textured samples. From the Scanning Electron Microscope (SEM) graphs, some particles were found in the textured samples, which were about several nanometer in size. The composition of these particles, however, leaves to be identified. The magnetic critical current density (Jcm) at 77K dropped rapidly with the increase of Mg content.

Both of the off-diagonal Seebeck effect and the off-diagonal Peltier effect were investigated with the use of the same textured sample YBa 2 Cu 3 O 7−δ (Y-123) and the same experimental setup. The reliability of the measurement is studied by applying different heat-conductive mediums. The flatness of both of the sample and the heat-conducting block, and the matching between them are found very important for the reduction of the heat resistance. The annealing effect on the S xz is also studied and found in accordance with that studied by the thermoelectric power.

Experiment devices and specimens are designed to simulate the combined cycle fatigue (CCF) phenomena occurred in fan and compressor blades of gas turbine engine. A uniaxial fatigue test machine is modified to conduct biaxial loadings through adding an electromagnetic shaker. Two plate specimens with or without middle platform are designed for CCF testing. The middle point of the specimen is chosen as the exciting point and two pins are used so that the interference between the two loading directions will be released. By means of FEA, it is approved that the system is suitable for CCF test of Titanium alloy and the similar materials.