JP2002194454A - METHOD FOR MANUFACTURING Nb-Ti ALLOY BY PACK ROLLING, AND Nb-Ti ALLOY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture an Nb-Ti alloy sheet for superconducting material to desired thickness at a low cost while obviating the necessity of special equipment for forming and many working steps, without recourse to special working conditions, with respect to a method for manufacturing an Nb-Ti alloy by pack rolling and the Nb-Ti alloy. SOLUTION: An Nb sheet and a Ti sheet are alternately laminated into 10 or more layers in total and integrated with each other. The resultant integrated material is subjected to pressure bonding by hot rolling to undergo metallic joining of the respective layers, by which a metal sheet having multilayered structure can be prepared. Subsequently, the resultant multilayered metal sheet is heat-treated at a temperature lower than the melting point (1680 deg.C) of Ti to form a solid-solution layer of Nb and Ti between the respective layers of Nb and Ti or form a solid solution of Nb and Ti over the whole of the material of the multilayered metal sheet. In this way, the Nb-Ti alloy composed of Nb/Ti/Nb-Ti solid solution or the Nb-Ti alloy in which the whole of the material is composed of a solid solution of Nb and Ti can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an NbTi alloy by lamination rolling suitable for producing an NbTi alloy for a superconducting material from a thin plate of Nb and Ti, and an NbTi alloy obtained by the method. About.

[0002]

2. Description of the Related Art Generally, an NbTi alloy is well known as a practical material as an alloy-based superconducting material.
The first thing developed as an alloy-based superconducting material was an NbZr alloy wire. However, the NbZr alloy wire had poor composite workability with the copper stabilizing material, and the practical magnetic field range was as low as 5 to 6 T [tesler]. For this reason, NbTi alloy wires having excellent workability into ultrafine multifilamentary wires and usable in a practical magnetic field range of 8 to 11 T have been put to practical use as an alloy-based superconducting material.

[0003] Conventionally, in the case of producing such an NbTi-based superconducting wire material, a so-called arc melting method is generally used.

[0004]

However, conventionally, in the case of producing an NbTi-based superconducting wire material by using the arc melting method, in order to produce a high critical current density Jc material, the workability of the raw material surface has to be improved. It is necessary to control the amounts of oxygen and nitrogen which cause the decrease, and also to control C, Fe, A
It is important to sufficiently control the incorporation of trace impurity elements such as l, Cu, Ni, Sn, Cr, and Si. Moreover,
It is necessary to control the segregation and precipitation of Ti during casting, and it is also necessary to appropriately control the cooling rate during solidification for uniform solid solution.

Therefore, conventionally, it is necessary to go through a number of processing steps before producing a final product as a material for NbTi-based superconducting wires, and there are many factors to be controlled in each production step. In addition, a special device is required, which has been a factor that greatly increases the product price.

Accordingly, an object of the present invention is to provide a superconducting material having a desired thickness simply and inexpensively without requiring any special processing equipment, without going through many processing steps, and irrespective of special processing conditions. An object of the present invention is to provide a method for producing an NbTi alloy for producing a thin plate for a material, and an NbTi alloy obtained by the method.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned conventional problems, and as a result, commercially available thin Nb plates and Ti plates have been alternately stacked, It has been found that a solid solution alloy in which two metals of Nb and Ti are mixed can be produced by hot rolling this laminate to join each layer to form a fine multi-layer structure plate and then performing high-temperature heat treatment. Thus, the present invention has been completed.

That is, the N according to the first aspect of the present invention.
In a method for producing a bTi alloy, for example, as described in the embodiment below, a total of 10 or more Nb plates and Ti plates are alternately laminated and integrated, and then the integrated laminate is hot-rolled and pressed. In this way, each layer is metallically joined to produce a single metal plate having a multilayer structure. Then, the multilayer metal plate is subjected to a heat treatment at a temperature equal to or lower than the melting point of Ti (1680 ° C.) to obtain each of Nb and Ti. A solid solution layer of Nb and Ti is generated between the layers, or Nb
And a solid solution of Ti and Ti. In addition, "the metal layers are joined" means that Nb and Ti are atomically bonded. That is, at the interface between the Nb layer and the Ti layer, Nb atoms and Ti atoms are mixed with each other.

According to the method for producing an NbTi alloy according to the second aspect of the present invention, for example, as described in the following embodiment, a total of 10 or more Nb plates and Ti plates are alternately overlapped and integrated, and thereafter, Each of the layers is metallically joined by hot rolling and pressing the integrated laminate to form a single metal sheet having a multilayer structure. Then, after the multilayer metal sheet is cold-rolled, A solid solution layer of Nb and Ti between the layers of Nb and Ti by performing a heat treatment at a temperature equal to or lower than the melting point (1680 ° C.), or a solid solution of Nb and Ti in the entire material of the multilayer metal plate. It is characterized by the following. Therefore, a multilayer metal plate having a finer layer structure is manufactured by "cold rolling" a multilayer metal plate of Nb and Ti which has been formed into a fine multilayer structure by hot rolling and compression.

[0010] According to a third aspect of the present invention, there is provided a method for producing an NbTi alloy, comprising the steps of: A total of 10 or more layers are laminated and integrated again, and the integrated laminate is hot-rolled and pressed again to join the respective layers metallically. This laminating and rolling step is repeated one or more times to further form a multilayer structure. It is characterized by being formed on a metal plate. Therefore, the thickness of each layer of the obtained multilayer metal plate can be further reduced in accordance with the number of times the lamination rolling process is repeated, and the subsequent heat treatment time is also reduced.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an NbTi alloy according to the first, second, or third aspect, wherein the periphery of the laminate is welded or made of iron. The laminate is sealed in a box and integrated.

According to a fifth aspect of the present invention, there is provided a method for producing an NbTi alloy according to the first, second, third or fourth aspect.
The plate and the Ti plate each have a thickness of 10 mm or less.

A NbTi alloy according to a sixth aspect of the present invention is manufactured by the manufacturing method according to the first, second, third, fourth or fifth aspect, for example, in the following embodiment. And

[0014]

Hereinafter, embodiments of the present invention will be described in detail.

According to the present invention, for example, a solid solution alloy of NbTi is manufactured through the following manufacturing steps. First, the Nb plate and the Ti plate are alternately laminated and integrated into a total of 10 layers or more.

As the Nb plate and the Ti plate, commercially available thin plates of Nb and Ti are used. These thin plates have a thickness of 0.1 mm.
It is 1 to 10 mm, and preferably 1 to 5 mm in consideration of availability of materials and workability of superposition. N
The number of b-plates and Ti-plates to be alternately stacked is 10 layers or more. When the number of layers is 10 or more, the thickness of each layer when the metal plate having a multilayer structure has a predetermined thickness can be reduced. By reducing the thickness of each layer, it is possible to shorten the heat treatment time when performing the heat treatment on the final rolled material in order to generate a solid solution layer of Nb and Ti, as described later.

As a means for laminating and integrating these Nb plates and Ti plates, a method of welding around the laminated layers or enclosing the laminated layers in an iron box and integrating them is preferable. is there.

In the present invention, after this integration step, the integrated laminate is hot-rolled and pressed to metallically join the Nb and Ti layers to produce a single metal sheet having a multilayer structure. Then, in this hot rolling step, the thickness of the Nb layer and the Ti layer is reduced to form a fine multi-layer structure, and Nb atoms and Ti atoms are mixed with each other at the interface of each layer to form a thin plate having a desired thickness. To form

Next, in the present invention, after the hot rolling step, the multilayer metal plate is subjected to a high-temperature heat treatment. The temperature of this heat treatment needs to be lower than the melting point of Ti (1680 ° C.). In this case, the temperature is preferably about 800 ° C. to 1000 ° C. in consideration of the workability and the problem of the heat treatment furnace. By performing the heat treatment on the multilayer metal plate as described above, Nb and Ti can be interdiffused and a solid solution layer of Nb and Ti can be generated between the layers of Nb and Ti. In this manner, the Nb-Ti-Nb-Ti solid solution is formed by forming a solid solution layer of Nb and Ti between each layer of Nb and Ti.
A bTi alloy is produced.

Further, in the present invention, in the heat treatment step, the heat treatment temperature is made higher than the above-mentioned temperature or the heat treatment time is made longer, so that the entire material of the multilayer metal plate becomes N
A solid solution of b and Ti can be generated. And
An NbTi alloy is produced in which the entire material is a solid solution of Nb and Ti.

Further, in the present invention, a material having a composite function can be produced by changing the composition of Nb and Ti in the thickness direction of the multilayer metal plate (alloy plate). That is, when alternately laminating thin plates of Nb and Ti, a desired composition of Nb · Ti in the thickness direction of the alloy plate is determined.
The thickness ratio of the Nb plate and the Ti plate to be laminated may be calculated in advance, and the Nb and Ti thin plates having a thickness suitable for the ratio may be laminated. Therefore, it is difficult to form such a composite by the conventional smelting method, but according to the present invention, a material in which the composition of Nb and Ti changes arbitrarily in the thickness direction can be obtained.

In the present invention, the multi-layered metal sheet produced by hot rolling and compression is once again laminated and integrated into a total of 10 layers or more, and the integrated laminate is again hot-rolled and compressed. Each layer can be metallically bonded to form a multilayer structure by repeating this laminating and rolling step once or twice or more. Therefore, the thickness of each layer of the obtained multilayer metal plate can be reduced according to the number of times the lamination rolling process is repeated, and the subsequent heat treatment time can be shortened.

Further, in the above-described embodiment, an example has been described in which a multilayer metal plate having a multilayer structure formed by hot rolling and pressing is directly subjected to a heat treatment step. The sheet may be cold-rolled, and then heat-treated at a temperature equal to or lower than the melting point of Ti (1680 ° C.) as described above. Therefore, the multilayer metal plate of Nb and Ti, which has been formed into a fine multilayer structure by hot rolling and compression bonding, can be manufactured as a multilayer metal plate having a finer layer structure by "cold rolling".

[0024]

Next, the present invention will be described in more detail with reference to the following examples. However, it goes without saying that the present invention is not limited to these examples.

EXAMPLE 1 A total of 31 layers of a pure niobium plate having a thickness of 1.0 mm × a width of 70 mm × a length of 140 mm and a pure titanium plate having the same dimensions are alternately laminated in a total of 31 layers. Inserted into a 170 mm iron box, placed on top and bottom an iron plate with a thickness of 3 mm × width 80 mm × length 150 mm, sealed and welded, heated to 900 ° C, and rolled to obtain a material with a multilayer structure of thickness 3 mm. did. This material was heated in a vacuum (10 ^-4 Torr) at a temperature of 1000C for 10 hours. As a result, NbTi is formed at the interface between the Nb layer and the Ti layer.
The formation of a solid solution of was confirmed. Furthermore, by reheating at a temperature of 1000 ° C. for 40 hours, N
Formation of bTi solid solution was confirmed.

[0026]

According to the present invention configured as described above, the following remarkable effects can be obtained.

According to the first aspect of the present invention, a total of 10 or more Nb plates and Ti plates are alternately laminated and integrated, and then the laminate is hot-rolled and press-bonded to make each layer metallic. To form a multi-layered metal plate, and heat-treat this multi-layered metal plate at a temperature equal to or lower than the melting point of Ti (1680 ° C.) so that Nb and Ti are interposed between the layers of Nb and Ti.
, Or a solid solution of Nb and Ti in the entire material of the multilayer metal plate, so that it does not require a special device for forming as in the prior art, and goes through many processing steps. In addition, a NbTi alloy having a desired composition and having a predetermined thickness mainly composed of a solid solution of Nb and Ti can be easily and inexpensively manufactured for a superconducting material without depending on special processing conditions.

According to the second aspect of the present invention, the multi-layer metal sheet hot-pressed and pressed is cold-rolled and then subjected to the heat treatment. The Nb and Ti alloy can be easily and inexpensively manufactured as a multi-layer metal plate of Nb and Ti having a fine multilayer structure as a multi-layer metal plate having a finer layer structure.

According to the third aspect of the present invention, the multi-layer metal plate produced by hot rolling and compression is once again used for a total of 1
After laminating 0 or more layers and integrating them, the laminate is hot-rolled and pressed again to join the layers metallically, and this lamination and rolling step is repeated one or more times to form a multilayer structure. According to the number of times the lamination rolling process is repeated, the thickness of each layer of the obtained multilayer metal plate can be reduced, and the heat treatment time thereafter can be shortened. As a result, the NbTi alloy for the superconducting material can be formed to a desired thickness. It can be manufactured simply and inexpensively.

According to the fourth aspect of the present invention, the Nb plate and the Ti plate are welded around the laminate before hot rolling, or the laminate is sealed in an iron box and integrated. The layers can be surely overlapped with each other, and the metal joining of each layer can be reliably achieved by the subsequent hot rolling of the laminate.

According to the fifth aspect of the present invention, by using the Nb plate and the Ti plate each having a thickness of 10 mm or less, it is easy to obtain as a material and the workability of the superposition can be improved. .

According to the sixth aspect of the present invention, it is possible to easily and inexpensively obtain an NbTi alloy mainly composed of a solid solution in which two kinds of metals, Nb and Ti, having a desired composition are mixed.

Claims (6)

[Claims] 1. A total of 10 or more Nb plates and Ti plates are alternately overlapped and integrated, and thereafter, the integrated laminate is hot-rolled and press-bonded to metallically join the respective layers to form one sheet. Then, a heat treatment is performed on the multilayer metal plate at a temperature equal to or lower than the melting point of Ti (1680 ° C.) to form a solid solution layer of Nb and Ti between each layer of Nb and Ti, Alternatively, the entire material of the multi-layer metal plate is N
A method for producing an NbTi alloy by lamination rolling, wherein a solid solution of b and Ti is generated. 2. An Nb plate and a Ti plate are alternately laminated and integrated into a total of 10 or more layers, and thereafter, the integrated laminate is hot-rolled and pressed to metallically join each layer to form one sheet. After a metal plate having a multilayer structure of the above was produced, and the multilayer metal plate was cold-rolled, the melting point of Ti (16
(80 ° C.) or lower to form a solid solution layer of Nb and Ti between each layer of Nb and Ti, or a solid solution of Nb and Ti in the entire material of the multilayer metal plate. Production method of NbTi alloy by lamination rolling. 3. The multi-layer metal sheet according to claim 1 or 2, wherein a total of 10 or more layers of the multi-layered metal plate produced by hot rolling and compression are laminated and integrated again, and the integrated laminate is hot rolled and pressed again. A method of producing an NbTi alloy by lamination rolling, wherein each layer is metallically joined, and this lamination rolling step is repeated one or more times to form a metal plate having a multilayer structure. 4. The NbT according to claim 1, wherein the laminate is welded around the laminate, or the laminate is sealed in an iron box and integrated.
Method for producing i-alloy. 5. The method according to claim 1, wherein the Nb plate and the Ti plate each have a thickness of 10 mm or less. 6. An NbTi alloy manufactured by the manufacturing method according to claim 1, 2, 3, 4, or 5.