In an austenitic Fe61.5Mn23Ni7Cr8.5 antiferromagnetic (afm) alloy deformation results in a splitting between magnetisation-vs.-temperature curves measured during field cooling (FC) below the Neel temperature and those measured at the same field after zero-field cooling (ZFC). Furthermore, a thermoremanent magnetisation (TRM) appears that corresponds to the splitting between zero-field and field cooled thermomagnetic measurements for a given cooling field and scales with the degree of deformation. This TRM is attributed to the deformation induced defects which act as a source of uncompensated magnetic moments and interact with the bulk afm moments. This interpretation is also supported by the fact that the net magnetic moments vanish above the Neel temperature. The TRM does not saturate in fields of up to 7 T, applied during cooling, and cannot be switched by fields up to 7 T. Within the investigated field range of -7 T to 7 T the magnetisation-vs.-field curves show a stable shift along the magnetisation axis. Thus, the uncompensated moments appear to be strongly exchange coupled to the afm matrix surrounding them. Within the series of experiments the maximum TRM reached after FC in 7 T corresponds to about 4 x 10(-4) mu(B)/atom (Bohr magneton) of the maximum deformed afm sample. The Neel temperature decreases due to deformation. (C) 2011 Elsevier B.V. All rights reserved.

By comparing the microstructural and texture evolution with tensile stress–strain response of an Fe–24Mn–7Ni–8Cr (mass%) alloy, a slip-dominated deformation process and, at a later stage of deformation, twinning-induced plasticity are observed. The occurrence of deformation twinning is texture sensitive and occurs only in the 〈111〉 fibre texture component. Based on these experimental observations, a model is presented, which reflects an orientational and configurational peculiarity of face-centred cubic stacking faults bordered by two Shockley partials. With this model, the onset point of stacking fault growth, i.e. movement of the leading partial and stopping of the trailing partial, is evaluated. This point reflects the formation of twins in the sense that a twin is regarded as an arrangement of stacking faults on every consecutive slip plane. Furthermore, based on the tensile test results, a model-compatible description of the mechanical behaviour is shown and a reasonable stacking fault energy of about 8mJm−2 is calculated for the onset of partial dislocation breakaway, i.e. the onset of deformation twinning.

Cube textured nickel alloy tapes prepared by cold rolling and annealing (RABiTS method) represent a standard metallic substrate for superconductor coatings of the YBa2Cu3O7−δ (YBCO) type. These tapes have a width to thickness ratio of about 30–100. However, a value of close to one is optimal concerning low energetic losses under alternating current applications. First experiments on micro-alloyed nickel prove that the cube texture as a typical sheet texture can also be formed in profile wires with a rectangular cross-section after cold drawing and recrystallization treatment.

The growth of the nanostructured YBa2Cu3O6+x (YBCO) films is investigated for the first time on biaxially textured NiW substrates used in coated conductor technology. The optimization process of superconducting layers is made in wide magnetic field and temperature range in order to understand the vortex pinning structure and mechanism in our films prepared from nanostructured material. Structural analysis shows that growth mechanism in YBCO films grown on NiW is completely different when compared to YBCO on STO. Films on NiW are much rougher, there is huge in-plane variation of YBCO crystals and moreover out-of-plane long range lattice ordering is greatly reduced. Magnetic measurements demonstrate that jc in films grown on NiW is higher in high magnetic fields and low temperatures. This effect is connected to the amount of pinning centres observed in films on metal substrates which are effective at low temperature range.

To avoid ferromagnetic hysteresis losses in alternating cur-rent applications of thin film superconductors, paramagnetic substrates are required at 77 K, the operating temperature of the superconducting YBa(2)Cu(3)O(7-x). Therefore the composition is modified starting from Ni5W to reduce the ferromagnetic Curie temperature. This temperature can be suppressed well below 77 K by adding Cr or further W to the alloys. It is shown that the Ni-W-Cr tapes can be processed, leading to at least 90% cube texture. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

An epitaxial Y(2)O(3)/YSZ/CeO(2) buffer architecture has been prepared on cube textured Ni-5 at.% W, Ni-7.5 at.% W and Ni-9 at.% W tapes using pulsed laser deposition. The buffer layer growth was studied in detail and revealed a good texture transfer throughout the structure on the global as well as on the local scale. YBCO (yttrium barium copper oxide) layers were successfully deposited on the buffered tapes, showing an in-plane texture spread of about 7 degrees. Microstructural investigations revealed clear interfaces and a homogeneous surface structure. A superconducting transition temperature of more than 89 K with a small transition width was observed for all metal substrates. A critical current density J(c) of more than 0.9 MA cm(-2) was measured inductively at 77 K in the self-field on all substrates.

Cube textured nickel substrate tapes and flat wires with an increased grain aspect ratio were prepared from nickel micro-alloyed with silver plus yttrium and silver, respectively. Whereas the maximum grain aspect ratio for the tapes was about 6, this value reached up to 14 for the flat wires.

Cube textured substrate tapes were prepared by cold forming and annealing from nickel highly alloyed with tungsten to manufacture flexible superconductors of the YBCO (YBa2Cu3O7-delta) type.It was shown that the fraction of more than 90% cube texture of the Ni-7.5 at.% W tape material enables the chance to produce YBCO-coated conductors with reduced ferromagnetism and increased mechanical strength.

The development of strongly cube textured Cu based substrates is important in the cost effective production of long lengths of high temperature superconducting cables. The present paper reports textures (deformation and recrystallisation) development in pure Cu, Cu–Al, Cu–Mn (with a solute content of 1–3 at.%) and Cu–35 at.% Ni alloys.

The development of cube textured flexible metallic substrate tapes is of basic interest for the economic production of YBa2Cu3Ox (YBCO) coated superconductors. Nickel tapes microalloyed with silver were prepared with the specific feature of an elongated grain structure. Cube textured NiO films were grown by surface oxidation epitaxy on these tapes retaining the elongated grains. Further, buffer layers and YBCO were deposited thereon. The YBCO layer transports an up to four times higher critical current density (Jc=2.35MA∕cm2) in the direction of grain elongation compared to the transversal one (Jc=0.55MA∕cm2).

A homogeneous nickel oxide film epitaxially grown on cube textured nickel tapes was prepared as a first buffer layer for subsequent buffer and YBa2Cu3Ox (YBCO) layer depositions. The nickel oxide film was produced under growth conditions of surface oxidation epitaxy (SOE). The preparation of homogeneous oxide films by SOE with a high texture quality and without disturbing columnar oxide growth succeeded on micro-alloyed nickel tapes. Cerium, yttrium and silver are proven beneficial elements for micro-alloying in this respect. In silver doped metallic substrates, the cube oriented grains were produced with an increased grain aspect ratio, which was transferred to the SOE nickel oxide. Increased transport currents in the YBCO coatings were measured in the longitudinal direction of the tapes, which were coated with an additional system of buffer layers. The critical current density reached up to Jc=2.35MA/cm2 at 77K in self field.

The critical current density J c is limited by the network of small angle grain boundaries in coated conductors based on biaxially textured metal substrates up to a texture dependent cross-over field. Below this cross-over field J c can be improved by optimizing the grain boundary network. One possibility to enhance J c at low magnetic fields is to use substrates with high aspect ratio grains. Therefore, cube textured Ni tapes micro-alloyed with silver were prepared having such an elongated grain structure with an aspect ratio of about 4. Highly textured NiO layers have been grown on these substrates using surface oxidation epitaxy (SOE). YBCO films were deposited afterwards on these substrates by pulsed laser deposition using a BaZrO 3 /SrRuO 3 buffer layer architecture. Transport measurements revealed a significant enhanced J c value along the rolling direction of the tape compared to the transverse direction. Similar results were obtained in numerical simulations based on measured EBSD texture maps.

A newly developed SrZr1−xTixO3 single perovskite buffer was successfully applied on surface oxidized Ni tapes leading to highly textured YBCO films. An inductively measured Tc above 88K and inductive Jc values up to 1MA/cm2 were achieved on Ni–0.1at.%Mo substrates indicating a similar quality as a standard BaZrO3/SrTiO3 double layer.

The preparation and properties of Tl-2212 (Tl2Ba2CaCu2O8) thin films on biaxially textured Ni substrates, buffered with CeO2/YSZ/CeO2 trilayers, have been studied. Tl-2212 thin films were grown using a two-step fabrication process that involved magnetron sputtering and low temperature post-annealing. XRD θ–2θ scans, rocking curves and φ-scans proved that the Tl-2212 thin films were epitaxially grown on the buffered RABiTS. The critical temperature Tc and critical current Jc (77 K, 0 T) were 103 K and 2.6 MA cm−2, respectively.

Cube textured NiO layers were prepared by surface oxidation epitaxy on microalloyed Ni tapes. Different perovskite buffers were successfully grown on these substrates using pulsed laser deposition. Among them, BaZrO3 and SrZrO3 buffers show an excellent epitaxial growth on NiO with an in-plane orientation similar to the underlying NiO. The subsequent deposition of YBa2Cu3O7-x on top of these buffers requires a thin intermediate SrTiO3 layer and results in epitaxial layers with a T-c of about 89 K and J(c) values up to 1.6 MA cm(-2). Alternatively, epitaxial SrRuO3 was grown on NiO using a thin intermediate BaZrO3 layer leading to YBCO films of similar quality. The investigation of the magnetic field dependence of the critical current density shows the major influence of the grain boundary network in the low-field region.