Papers by Keyword: Cube Texture

Abstract: The influence of an electric field on the annealing of high purity (99.999%) cold rolled nickel has been investigated. Annealing was carried out for 2 hours at temperatures between 300oC and 800oC with and without an electric field of strength 2.0KVcm-1. The microstructure and fraction of cube texture resulting were characterized using electron backscattering pattern (EBSP) technique. Annealing in an electric field leads to somewhat smaller average values of the cube fraction and grain sizes compared to annealing without an electric field. The highest temperature (800oC) annealing in an electric field results in microstructures with a lower fractional twin boundary length.

Abstract: Ni-3at.%W alloy tapes for YBCO coated conductor were fabricated by powder metallurgy process including powder compaction, cold isostatic pressing(CIP), cold rolling and annealing for recrystallization. The Ni-3at.%W tapes annealed in an atmosphere of 96%Ar and 4%H2 mixing gas were characterized by X-ray pole figures, orientation distribution function(ODF) and optical microscopy(OM). The Ni-W alloy tapes were heat-treated at 700~1000°C for the development of cube texture {001}<100>. The texture analysis indicated that as fabricated tapes have a sharp cube texture after annealing at 900 and 1000°C. Also, thoroughly recrystallization takes place for the annealed tapes at the both temperatures and the average grain size of the two tapes is about the same, which is about 35㎛.

Abstract: Influence of cold rolling total thickness reduction, annealing temperature and annealing time on the textures in powder metallurgic Ni-5at.%W substrate tapes have been quantitatively investigated with the EBSD (Electron Back-Scattered Diffraction) technique. A “copper” type-like texture consisting of {1 2 3}<6 3 –4>+{0 1 –1}<3 –1 –1>+{1 –1 2}<1 –1 –1> has been found in the as-rolled tapes. This texture was much intensive in the tape at 99% thickness reduction than in the tape at 87% thickness reduction. The 99% reduction tape showed a higher fraction and sharper cube texture than the 87% reduction tape after annealing treatment. In addition, annealing at 1000°C was much favourable for the cube texture formation than annealing at 950°C and resulted in a higher cube texture fraction.

Abstract: We fabricated bi-axially textured pure Ni and Ni–5at.%W (Ni-5W) alloy tapes for the application of rechargeable battery cathode and coated superconductor, where the controlled microstructure of the substrate plays a critical role. The sintered Ni or Ni-W rods were cold-rolled into the thin tapes of 80 ~ 100 µm thickness, and the tapes were heat-treated for texture development with a line focused infrared heater. The temperature was maintained at 800 ~ 1050 °C, using a 1kW double ended linear halogen lamp in 96%Ar-4%H2 atmosphere. The (2 0 0) texture of Ni tape was successfully formed through optimization of the recrystallization infrared heating condition for the cold rolled Ni tapes. The full width half maximum of the Ni tapes was less than 10o, and the grain size was 20 ~ 40 µm. Focused IR-heating resulted in a better texture development and smaller grain size compared to the conventional resistive heating because of the steep temperature gradient.

Abstract: The recrystallization behavior and texture development in copper accumulative roll-bonding (ARB) processed by various cycles (2, 4 and 6 cycle) were studied by differential scanning calorimetry (DSC) analysis and SEM/EBSP method. The exothermic peaks caused by recrystallization appeared at 210 ~ 253 􀍠 in each sample. The peak positions shifted to lower temperature as the number of ARB cycles increased. This result indicated that the evolution of finer microstructure with increasing number of the ARB cycles enhanced the occurrence of recrystallization at lower temperature. The stored energy calculated from the DSC curve of the ARB processed copper increased with the increasing strains. During an annealing, the preferential growth of cube-oriented grains ({100}<001>) occurred in each sample. The recystallization behavior of ARB processed copper having low stacking fault energies was distinguished from that of so-called “recovery type” materials, i.e. aluminum and low carbon steels, which shows rather continuous changes in microstructure during annealing. The accumulated strains provided the driving force for the preferential growth, which was the same mechanism as the preferential growth in normally rolled copper. The sharpest cube texture developed in ARB processed copper by 4 cycles. The difference of cube texture development between 2 cycles and 4 cycles was caused by the distribution of cube-oriented regions which corresponded to the nucleation sites of recrystallized grains before annealing. More nanocystalline layers in the vicinity of bonded interfaces were distributed in ARB processed copper by 6 cycles than 4cycles. The nanocystalline structure could grow faster than the cube-oriented grains and led to the inhibition of sharp cube texture in the ARB processed copper by 6 cycles.

Abstract: The texture evolution during hot and cold rolling of AlMg1Mn1 can body sheet is described and the related anisotropy effects during deep drawing are analysed quantitatively. The typical textures of rolled aluminium show the transition between ß-fibre orientations and cube recrystallization texture, depending on rolling temperature and strain. These correlate with transitions between 45° and 0°/90° ear heights in deep drawn cups which are described by a new method of Fourier series expansion. Processing parameters to achieve low anisotropy are discussed.

Abstract: In Pt-10mass%Rh alloys which were recrystallized using full annealing at or above 1273K after the cold rolling with the reduction ratio of both 90% and 98%, the formation of cube texture has already been found. When these primary recrystallized alloys are subjected to the further annealing at higher temperatures, the occurrence of the secondary recrystallization can be expected. In this study, the development of the cube texture and the process in the coarsening of crystal grains during the secondary recrystallization were investigated. In addition, the creep tests were carried out for the secondary recrystallized alloys and resultant creep properties were compared with those for the primary recrystallized alloys. It became clear that the cube texture which further developed during the secondary recrystallization in 98% rolled specimens exhibits the greater thermal stability than that in secondary recrystallized 90% rolled ones. During the secondary recrystallization, it was confirmed that the grains coarsened according to the law of tm, where t and m show time and a constant, respectively. The higher development of the cube texture and the coarsening of grains during the secondary recrystallization were found to have remarkable effects of improving the creep resistance.

Abstract: Deformation and primary-recrystallization textures in nickel alloys with some metals (Nb, to 5.4%; W, to 7.4; Re, to 4.1%; Mo, to 9.3%; V, to 10.1%; Mn, to 22.1%; Al, to 12.0% and Cr, to 22.0%) has been studied depending on the content of alloying elements and the rolling temperature. The dependence of the type of recrystallization texture on the component composition of the deformation texture has been established.

Abstract: Pure Ni, Ni-5at.%Mo and Ni-5at.%W prepared through P/M route have been severely cold deformed (~95%) and given different heat treatments to develop sharp cube component ({001}<100>) for coated superconductor applications. It was found that amongst the three materials studied, Ni-5at%W develops the most sharp cube texture. This is in contrary to the observation in similar materials produced by the melting and casting route.

Abstract: YBa2Cu3O7-δ ("YBCO") is a high-temperature ceramic superconductor. Due to its complex layered structure, a strong biaxial texture of the YBCO grains is necessary to achieve technically relevant currents. In this paper, we describe the development of flexible metallic tapes with strong cube texture, providing a lattice-matched template for buffer and YBCO coatings in proper orientation. Texture analysis was performed using electron backscatter diffraction (EBSD).