Effect of different deformation and annealing procedures on non-magnetic textured Cu_(60)Ni_(40) alloy substrates

In this work,a series of specimens was prepared by the casting method.Sharp cube-textured substrates were processed by heavy cold rolling and recrystallization annealing(i.e.,the rolling-assisted biaxially textured substrates(RABi TS) method).Both the rolling and the recrystallization texture in the alloy tapes were investigated by X-ray diffraction and electron back-scatter diffraction,respectively.The results showed that a strong copper-type deformation texture was obtained in the heavy cold-rolled substrate.In addition,the recrystallization annealing process was found to be very important for the texture transition in the Cu–Ni alloy substrates.The cube texture content in the Cu60 Ni40 alloy substrates reached 99.7%(≤10°) after optimization of the cold-rolling procedure and the recrystallizing heat-treatment process,whereas the content of low-angle grain boundaries(from 2° to 10° misorientation) in the substrate reached 95.1%.

Thermophysical properties of solution precursor plasma-sprayed La2Ce2O7 thermal barrier coatings

La2Ce2O7 (LCO) is a promising candidate for thermal barrier coatings (TBCs) due to that it provides better thermal insulation than yttria-stabilized zirconia (YSZ) does. In this work, a TBC LCO was produced by solution precursor plasma spraying (SPPS). After the solution precursors were prepared and the spraying parameters were optimized, the thermophysical properties and thermal shock performance of the coatings were tested. It was found that the SPPS coating with segmentation crack density of 6 mm^-1 had the porosities of about 33.5% at spray distances of 35 mm. The thermal conductivity of the SPPS coatings is 0.50-0.75 W·m^-1·K^-1, much lower than that of the atmospheric plasma spraying (APS) coatings (0.85-1.25 W·m^-1·K^-1). The thermal shock performance of the SPPS coatings reached 60 cycles, much better than the APS coatings. This improvement is due to the segmentation cracks in the coatings, which can improve strain tolerance and effectively relieve internal stress. This study provides reference significance for further research on thermal barrier coatings.

Electropolishing technique of Hastelloy C-276 alloy

Preparing a highly textured,flawless YBa_（2-）Cu_3O_7（YBCO）layer by ion-beam-as sis ted deposition（IBAD）requires a substrate with a smooth surface.In this paper,smooth tapes of Hastelloy C-276,a common template alloy,were prepared by electrochemical polishing,and the surface roughness the tapes was investigating by atomic force microscopy and scanning electron microscopy.By analyzing these results,it was discussed how the processing parameters affect the surface roughness,and it is found the following optimized processing parameters：current density of 0.104 A·cm^（-2）,temperature of 50℃,plate spacing of 9 cm and time of 150 s.With these optimized parameters,the substrate roughness decreases to less than 5 nm,meeting the requirements of IBAD.

Continuous electropolishing technique for long-length Hastelloy C-276 tape

Preparation of the second-generation high-tem- perature superconducting tape by ion beam-assisted depo- sition （IBAD） requires a flat metal substrate. In this work, the electrochemical polishing of long-length Hastelloy C-276 alloy was studied, and its process parameters, characterized roughness and other properties were inves- tigated. A 10-meter-long Hastelloy C-276 alloy was pre- pared by electrochemical polishing. The following optimized processing parameters are obtained： temperature of 45 ℃, current density of 0.439 A.cm-2 and polishing time of 60 s. The average roughness value （Ra） of the surface is less than 5 nm （5 μm × 5 μm）, which was characterized by atomic force microscopy. This value sat- isfies the requirements for the further preparation of tran- sition-layer pair by the IBAD technology route.

Cube texture evolution of Ni5W alloy substrates and La-Zr-O buffer layer of YBCO-coated conductors

The cube texture evolution of Ni-5 at%W alloy deformed up to a very high strain was thoroughly investigated by X-ray diffraction(XRD) and electron back-scattered diffraction(EBSD) during the process of deformation,recrystallization and grain growth.A typical copper-type rolling texture,mainly consisting of components of S,copper and brass orientations,is obtained after heavy cold rolling.The fraction of rolling texture is slightly strengthened during recovery and then strongly reduced during recry stallization process.The cube texture is formed by consuming the rolling texture components during the discontinuous recry stallization process.The cube grains have a size advantage with respect to the non-cube grains.A strong cube-textured Ni5 W alloy substrate with cube texture area fraction of 98.2 %(<10°) is obtained after annealing at 1050℃ for 1 h.The full width half maximum(FWHM) values for the X-ray(111) φ-scan and the(002)ω-scan of this substrate are 5.84° and 4.76°,respectively.Furthermore,the area fraction of {001}(110) orientation of the epitaxially grown La_(2)Zr_(2)O_(7) buffer layer is 97.1 %(<10°),and the FWHM values of(111) φ-scan and(002)ω-scan are 5.22° and 5.00°,respectively.

Cube texture formation of Ni9.3W alloy substrates:preparation by optimized deformation sequence and anneal process

The Ni9.3W alloy with no ferromagnetism and high yield strength is one of the most promising textured substrate materials for coated conductors, but its low stacking fault energy makes it difficult to obtain a strong cube texture by traditional rolling methods and recrystal- lization anneals. This paper introduces four-time static recoveries during the rolling process. Rolled tapes with 80 μm in thickness were obtained by applying various deformation sequences between static recoveries to study their effects on the cube texture formation in Ni9.3W alloy substrates. The results show that rising gradient deformation sequence is an advantageous way to obtain a higher amount of cube texture, its content increases by 29.2% compared to that of traditional deformation sequence. The effect of the new recrystallization annealing process on the cube texture formation was analyzed. It is shown that the cube texture content increases with anneal temperature increasing in one-step anneal, but decreases again at higher anneal temperature. Two-step anneal could effectively improve the cube texture content, which could be further enhanced by extending holding time during the first-step anneal. However, too long holding time leads to the decrease in cube texture content. Finally, Ni9.3W alloy substrates with a cube texture content of -90.0 vol% （〈15°） are obtained by optimized two-step anneal.