I. V. Gervas’eva

Perfect cubic texture, structure, and mechanical properties of nonmagnetic copper-based alloy ribbon substrates

A sharp cubic texture is formed in a number of copper alloys subjected to cold deformation by rolling by 98.6–99% followed by recrystallization annealing, which opens up fresh opportunities for long thin ribbons made of these alloys to be used as substrates in the production of second-generation high-Tc superconductor (2G HTSC) cables. The possibility of creating ternary alloys based on a binary Cu-30 at % Ni alloy with additional elements that harden its fcc matrix (iron, chromium) is shown. The measurements of the mechanical properties of textured ribbons made of these alloys demonstrate that their yield strength is higher than that of a textured ribbon made of pure copper by a factor of 2.5–4.5.

Choice of copper-based alloys for ribbon substrates with a sharp cube texture

It has been shown that, in some copper-based alloys subjected to cold deformation by rolling to 98.6–99% followed by recrystallization annealing, a sharp cube texture can be produced. Optimum conditions of annealing have been determined, which make it possible to produce a sharp biaxial texture in Cu-Ni, Cu-Fe, and Cu-Cr alloys with the fraction of cube grains of more than 95%; this opens a possibility of using thin ribbons made of these alloys as substrates for multilayer film compositions, in particular when developing second-generation high-temperature superconductors.

Formation of cube texture during annealing of rolled tapes from alloys Ni95.3Mo4.7 and Ni48.8Fe51.2

The paper deals with the study of the process of the formation of the primary recrystallization texture in Ni95.3Mo4.7 and Ni48.8Fe51.2 nickel alloys during annealing after deformation by rolling to large reduction. The electron backscatter diffraction method is used to show the effect of the temperature and the heating rate during annealing on the structure and texture in alloys that differ in the temperature of the beginning of primary recristallization. The majority of attention is focused on investigating the possibility of estimating the temperature range of primary recrystallization from the dilatometry anomaly on the temperature dependence of the thermal expansion coefficient. Variations in the relief of the rolled tapes after recrystallization are studied.

Creating textured substrate tapes of Cu-Fe alloys for second-generation high-temperature superconductors

It is established that Cu-1.6 at % Fe alloy tapes obtained through cold rolling to 98.9% followed by recrystallization annealing possess a sharp cube texture, which opens prospects of using thin tapes of this alloy as substrates for second-generation high-temperature superconductors. The optimum regime of annealing is determined that allows an alloy with sharp biaxial texture containing more than 97% cubic grains to be obtained. The yield stress of a 90-μm-thick Cu-1.6 at % Fe alloy tape upon recrystallization annealing at 800°C for 1 h amounts to 78 MPa, which is about three times higher than the value for a pure copper tape with sharp cube texture.

Creation of ternary Ni-Cr-W alloys with a sharp cube texture and a curie temperature below 77 K to produce epitaxial substrates for superconducting compositions

The texture, structure, and magnetic and mechanical properties of thin tape substrates fabricated of nickel alloys with chromium and tungsten have been investigated. It has been shown that in Ni89.6Cr8.6W1.8 and Ni89.6Cr7.8W2.6 alloys a sharp cube texture can be formed, which is stable up to high annealing temperatures. In the Ni89.2Cr7.2W3.6 alloy, other orientations are present along with a cube component. The possibility of obtaining a sharp cube texture after primary recrystallization is connected with the quantitative relationship between the texture components in a cold-rolled tape, which is determined by the method of orientation-distribution functions. The alloys studied are paramagnetic at 77 K.

Effect of recrystallization annealing on the formation of a perfect cube texture in FCC nickel alloys

Based on the data of X-ray diffraction, dilatometry, transmission electron microscopy, and electron backscatter diffraction, the optimum regimes of heat treatment of cold-rolled (to 98.5–99%) tapes made of binary Ni-W, Ni-Cr, Ni-Fe and ternary tungsten-containing Ni-Pd-W and Ni-Cr-W alloys that are widely utilized in the world practice for the fabrication of high-temperature superconducting cables of the second generation, which make it possible to obtain a perfect cube texture. In all five alloys, the spreed of the texture upon slow heating and two-step annealing decreases by 0.2°–1.5° around the RD and by 0.1°–0.6° around the RD in comparison with the single-stage high-temperature annealing.

Structural aspect of delamination crack formation during the HTMT of steels with a ferritic structure

The fine structure, texture, and fracture of the ferritic 08Kh18T1 steel subjected to repeated hot rolling at temperatures of 800–1100°C and reductions of 35, 50, and 65% have been studied. When significant strains are reached, a layered subgrain structure forms in the steel, and {100} and {111} planes are predominantly located in the rolling plane. The mechanisms of delamination crack formation during rolling under HTMT conditions are considered. The development of a crack in a material with a layered structure is analyzed theoretically.

Investigation of the structure and magnetic and mechanical properties of textured substrates of an Ni-Cr-W alloy

Based on the data of X-ray diffraction, electron-backscatter diffraction, dilatometry, thermal analysis, and scanning electron microscopy, we determined the optimum regimes of heat treatment of cold-rolled tape substrates of an alloy Ni88.4Cr9.2W2.4 that permit obtaining a perfect cube texture. It has been shown that the use of two-stage annealings makes it possible to obtain in this ternary nickel alloy a cube texture in which the scatter about the rolling direction (RD) and the transverse direction (TD) of the substrates varied within 6.75°–7.20° and 4.8°–5.4°, respectively.

NiCrM (M = W, Mo, V) ternary alloy tapes as cube-textured substrates for second-generation superconducting cables

Development of the deformation texture and recrystallization processes have been studied in some ternary nickel-based alloys of the Ni-Cr-W, Ni-Cr-Mo, and Ni-Cr-V systems. An optimum relationship between the amounts of the alloying elements upon the combined alloying of nickel has been found. Problems of the optimization of the regimes of recrystallization annealing have been considered, which are related to an increase in the temperature of the onset of primary recrystallization in ternary nickel alloys after deformation by rolling to large reductions. An analysis of mechanical and magnetic properties of all the alloys has been performed.

Textured Ni-Cr-W alloy substrates with curie temperatures below 77 K for high-temperature superconductors of second generation

Data on the texture, structure, and magnetic and mechanical properties of thin tape substrates made of nickel-based ternary alloys with chromium and tungsten are presented. It is established that, in Ni89.1Cr9.1W1.8 and Ni89.1Cr8.3W2.6 alloys, a sharp cube texture can be formed as a result of the primary recrystallization, which is stable up to high annealing temperatures. Using the method based on an analysis of the orientation distribution function, the ratio of main texture components that ensures the formation of the sharp cube texture in a cold-rolled tape upon the subsequent annealing has been determined. The Ni-Cr-W alloys studied have Curie temperatures below 77 K.