KR20060119955A - Nickel-based semifinished product with cube recrystallization structure and its manufacture and use - Google Patents

Abstract

The present invention relates to nickel-based semifinished products having a cube recrystallized structure and methods and uses for their preparation. Semifinished products can be used, for example, as a support for physicochemical coatings having a high microstructural arrangement. Such a support is suitable as a substrate for ceramic coatings, for example as used in the field of high temperature superconductors. In these cases, the product is used in superconducting magnets, transformers, motors, tomography and superconducting current paths. It is an object of the present invention to provide a nickel-based semifinished product having improved performance characteristics when used as a support for physicochemical coatings having a high microstructural arrangement. In particular, the semifinished product should have a higher, thermally more stable cube structure, substantially inhibiting the formation of grain size grooving. For this purpose, Ag in the microalloy range is added to the semifinished material, and the added Ag is 0.3 atomic% or less. The semifinished products of the invention are suitable, for example, as supports for physicochemical coatings having a high microstructural arrangement.

Description

NICKEL-BASED SEMIFINISHED PRODUCT HAVING A CUBE RECRYSTALLIZATION TEXTURE, CORRESPONDING METHOD OF PRODUCTION AND USE}

The present invention relates to a nickel-based semifinished product having a cube recrystallized structure and a method for producing the same.

Semifinished products can be used, for example, as a base for physicochemical coatings arranged in highly microstructured structures. The base is suitable as a substrate for ceramic coating, for example as used in high temperature superconducting applications. In this case the semifinished product is used in superconducting magnets, transformers, motors, tomographs or superconducting current paths.

It is known that polycrystalline metals comprising cube surface centered grids, ie nickel, copper and aluminum, etc., can form a tissue with a cube state upon subsequent recrystallization after a strong cold forging preceded by rolling (G. Wassermann: Organization of Metallic Materials, Springer Publishers, Berlin, 1939). Metal strips organized in this manner, in particular nickel strips, are used as bases for metal coatings, ceramic buffer layers and ceramic superconducting layers. Suitability as substrate material of the metal strip mainly depends on the degree of achievement of the tissue and the stability of the tissue within the temperature range for carrying out the coating process.

Organized semi-finished products for the production of high temperature superconductors are known, which are composed of Ni-Cr, Ni-Cr-V, Ni-Cu and similar alloys (US 5, 964, 966; US 6, 106, 615). ).

Ni alloys containing Mo and W are also known for this purpose (DE 100 05 861 C1).

Known semifinished products have the following disadvantages.

Nickel has a very strong tendency to form coarse structures which are undesirable for achieving high cube structure after cold forging and recrystallization annealing.

Cold forged Ni strips have a very strong tendency to form grain boundary grabs, especially at higher temperatures (800-1500 ° C.) during recrystallization heat treatment.

Grain size grabs can significantly inhibit the formation of highly biaxial cube tissue.

Substrate materials comprising grain size grabs are not very suitable as bases for epitaxial layer deposition, such as buffer and superconducting layers.

It is an object of the present invention to provide a nickel-based semifinished product having improved use properties for use as a base for physicochemical coatings arranged in a microstructure. In particular, the semifinished product should have a highly and thermally stable cube structure and should be prevented to allow the formation of grain size grabs. It is also included in the object to provide a method for producing the semifinished product.

This object is achieved by the material of the semifinished product comprising Ag additives in the microalloy range, wherein the Ag additive is at most 0.3 atom-%.

According to a preferred embodiment of the invention the Ni alloy may comprise Mo and / or W as the alloying element.

The semifinished product may be provided with a cube organized NiO layer having an amount of tissue in excess of 90% in accordance with the present invention. The layer is suitable as a diffusion barrier and can form a high quality coating layer, especially under oxidizing conditions.

The Ag additive according to the present invention supports the formation of highly cubed tissue and prevents the formation of grain size grabs on the Ni surface of the semifinished product. Ag additives also allow for high epitaxial growth by NiO layers with cube structure in semi-finished products.

The process according to the invention for the production of semi-finished products is characterized in that the semi-finished products are first produced by smelting metallurgy or powder metallurgy taking into account the mechanical alloys, which semi-finished products are technically pure Ni containing Ag additives in the microalloy range or Ni alloy, the additive being at most 0.3 atom-%. The semifinished product is then processed into strips or flat wires by subsequent high cold forging with a thickness reduction of more than 80% through hot forging. Finally the product can be recrystallized annealed to achieve cube organization.

After or during recrystallization annealing, the semifinished product prepared above may be heat treated in an oxidizing atmosphere for epitaxial growth of a cube-structured NiO layer in accordance with the present invention.

The semifinished product can be used according to the invention as a base for physicochemical coatings arranged in highly microstructured structures, in particular for producing high temperature superconductors in the form of wires or strips.

The invention is illustrated in detail by the examples which follow, which illustrate the successful implementation of the invention. Some of the implementation results are recorded in FIGS. 1 and 2 and Table 1 below.

Example 1

Functionally pure nickel with a purity of 99.9 atom-% Ni is transferred to the die cast under an alloy of 0.01 atom-% silver. The ingot is rolled into a cube structure (22 × 22) mm 2 at 1000 ° C., annealed and metallized while homogenized. Subsequently the cube material is cut and modified to obtain a defect free surface for subsequent cold forging by rolling. Cold rolling is carried out to a degree of rolling of at least 80%, in this case 99.6% thickness reduction. The resulting nickel strip has a thickness of 80 μm and is highly rolling organized. The annealing treatment is then performed at 550 ° C. for 30 minutes in a non-oxidizing gas atmosphere.

The result is very sharp cube recrystallized tissue, as can be seen in the strip according to FIG. 1. The amount of microcrystals with a cube state is 98% and the amount of incinerated crystal grains is 98% as well. The full width at half maximum of the (111) -pole intensity upon X-ray diffraction is FWHM = 4.4 °.

Example 2

Functionally pure nickel with a purity of 99.9 atom-% Ni is melted in a vacuum induction furnace under an alloy of 0.01 atom-% silver and transferred to the die cast. The ingot is rolled into a cube structure (22 × 22) mm 2 at 1000 ° C., uniformly annealed and metallized. Subsequently the cube material is cut and modified to obtain a defect free surface for subsequent cold forging by rolling. Cold rolling is carried out to a degree of rolling of at least 80%, in this case 99.6% thickness reduction. The resulting nickel strip has a thickness of 80 μm and is highly rolling organized. It is then annealed in a reduced gas atmosphere at 550 ° C. for 30 minutes.

The result is an almost complete cube recrystallization organization. The strip is subsequently exposed to the oxide for 5 minutes at 1150 ° C. in pure oxygen gas.

The resulting nickel oxide layer has a cube structure and 97% of the particles have a cube state. The tissue is rotated 45 ° relative to the tissue of the nickel strip (see FIG. 2). The half width of the (111) -pole is 6.2 °.

Example 3

Functionally pure nickel is melted under an alloy of 0.1-% silver and transferred to the die cast. The ingot is rolled into a cube structure (22 × 22) mm 2 at 1000 ° C., uniformly annealed and metallized. Subsequently the cube material is cut and modified to obtain a defect free surface for subsequent cold forging by rolling. Cold rolling is carried out with a rolling degree of 85% thickness reduction. The resulting nickel strip is 3 mm thick and subsequently annealed at 850 ° C. for 30 minutes for recrystallization. The surface is then cleaned and the strip is cold deformed to 80 μm thickness. It is subsequently annealed at 850 ° C. for at least 45 minutes in reduced atmosphere to form cube tissue.

Example 4

Functionally pure nickel powder is a powder metallurgical process by adding 4.0 atom-% tungsten powder and 0.1 atom-% silver powder. After pressing, tempering and hot forging a bar material of (12 × 12) mm 2 is obtained. The surface is cut and modified to obtain a defect free surface for subsequent cold forging by rolling. Cold rolling is carried out from a size of (10 × 10) mm 2 to a manufacturing size of 80 μm thick. The edge regions of the strip are separated and scattered. The resulting nickel strip is first annealed in a reduced gas atmosphere at 550 ° C. for 30 minutes for recrystallization. The strip is then second annealed in a reduced atmosphere at 1100 ° C. for 8 minutes to obtain a cube state that can be subjected to high thermal loads.

In Table 1, the values of substrates 5 and 6 show the positive action of the Ag additive according to the present invention on the FWHM (111) value, unlike the prior art (substrate 1-4).

Board FWHM (111) value Recrystallization Recrystallization 550 ° C, 30 minutes 850 ° C, 30 minutes One Ni 8.3 - 2 Ni + 0.1 Atom% Mo 7.4 7.2 3 Ni + 0.1 Atom% W 8.8 8.6 4 Ni 7.9 6.8 5 Ni + 0.05 Atom% Ag 4.8 5.1 6 Ni + 0.01 Atom% Ag 4.4 5.3

Claims (6)

In a nickel-based semifinished product having a cube recrystallized structure, consisting of functionally pure Ni or Ni alloy, Said component comprises an Ag additive in the microalloy range, said Ag additive being at most 0.3 atom-%. The nickel-based semifinished product with a cube recrystallization structure according to claim 1, wherein the Ni alloy includes Mo and / or W as alloy elements. 3. The nickel-based semifinished product with cube recrystallized tissue according to claim 1 or 2, wherein the semifinished product is provided with a cubed NiO layer having an amount of tissue greater than 90%. First, semi-finished products are formed of functionally pure Ni or Ni alloys containing up to 0.3 atomic-% Ag additives in the microalloy range, taking into account mechanical alloys by smelting metallurgy or powder metallurgy, after which the semi-finished product is more than 80% The semifinished product according to claim 1 or 2, which is processed into strips or flat wires by hot forging with subsequent high cold forging of thickness reduction, and finally the semifinished product is recrystallized annealed to achieve cube structure. How to prepare. The method according to claim 4, wherein the semifinished product is heat treated in an oxidizing atmosphere for epitaxial growth of the cube-structured NiO layer after recrystallization annealing or during annealing. 4. The cube recrystallized tissue according to any one of claims 1 to 3, which is used as a base for physicochemical coatings arranged in highly microstructured structures for the production of high temperature superconductors in the form of wires or strips. Nickel-based semifinished product with

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