JPH04160126A - TiA1 intermetallic compound plate material and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention... Regarding TiAl intermetallic compound plate material and its manufacturing method, among intermetallic compound materials that are expected to be used as structural materials such as next-generation lightweight heat-resistant materials, a plate-shaped TiAl intermetallic compound is manufactured by laminating thin plates. The invention relates to a novel method for

[Conventional technology]

The TiAl intermetallic compound is a structural material that has suddenly attracted attention in recent years, and many research institutions are conducting basic and applied research toward its practical application.

However, this TiAl intermetallic compound has not yet reached the stage of practical use, and in fact, there are only a few examples of experiments in which it has been processed into the shape of some practical parts, but only on cast products rather than processed products. Only a few cases have been reported.

This indicates that in order to put the TiAl intermetallic compound into practical use as a structural material, the problem of brittleness that this material has must be overcome. That is, this type of intermetallic compound has properties intermediate between those of metal materials and ceramics, and is characterized by being much more brittle than general metal materials. Therefore, plastic working at room temperature is almost impossible, and most of the current research on TiAl intermetallic compounds is focused on how to impart ductility at room temperature. Furthermore, the goal of this research is to provide at most a few percent of room temperature ductility, which is not something that can withstand high processing such as cold rolling.

That is, even with this TiAl intermetallic compound, the temperature at 800″C
Plastic working is possible at above hot temperatures, but at room temperature,
Only a few experimental successes have been achieved using a special plastic processing technique called lateral pressure extrusion as a plastic processing method. Therefore, for now. TiAl
The reality is that there are no reports of manufacturing thin plate coils made of intermetallic compounds, even at the laboratory level.

[Problem to be solved by the invention]

Conventionally, as a method to overcome the brittleness of such TiAl intermetallic compounds, research has been carried out on the addition of a third element, microstructural control, and the like. However, the target value for brittleness improvement is at most a few percent of room temperature ductility, and it can be said that it is difficult to manufacture thin plates or ribbons, at least using conventional processing methods. Therefore,
For example, even if a material with sufficient properties as a heat-resistant material is developed by adding a third element, if a thin plate-like material is required, such as for high-temperature springs or combustion engine linings, It is thought that practical application will be difficult due to restrictions on product shape and manufacturing costs.

An object of the present invention is to solve the problem of the prior art in that it is difficult to thin the coil by establishing a technique that enables the production of a thin plate coil of TiAl intermetallic compound without melt casting.

[Failure to solve the problem]

As a result of intensive research in line with the above objectives, the present inventors focused on a manufacturing method that utilizes so-called reaction diffusion, which does not require melting the material or going through a cold working process, which was previously difficult. A new method for producing plate-like products of TiAl intermetallic compound was developed.

To explain the outline of the newly proposed manufacturing method, first, Ti and A1 are made into a thin plate (foil plate) using a known method.
Then, by laminating each thin plate in two or more layers with the thickness adjusted so that the composition of the final material as a whole meets the target, and then heat-treating this multilayer laminate, the laminated Ti and A1 to cause reaction diffusion, thereby forming a TiAl intermetallic compound having a uniform composition throughout the material.

That is, in the present invention, the composition of the intermetallic compound obtained by thermally diffusing an interlaced laminated material of TiN plates and At thin plates can be adjusted by adjusting the thickness of the thin plates and the number of laminated layers.
A TiAl intermetallic compound plate material is provided, which is characterized in that the intermetallic compound has a desired composition in terms of atomic ratio.

Such TiAl intermetallic compound plate material is basically produced by stacking Ti thin plates and Al thin plates in close contact with each other alternately in the production of TiAl intermetallic compound. Adjust the ratio of each plate thickness so that they match in terms of atomic ratio, and subject the thus obtained Ti-Al composite laminate to a diffusion heat treatment at a temperature of 400°C or higher and 1460°C or lower for 1 second to 100 hours. It can be manufactured by

Further, the present invention provides Ti-Al in the above manufacturing method.
The lamination form of the composite laminate is a 3-layer laminate consisting of a Tiff board as a core and Al thin plates laminated as outer layers on both sides as a reference material, and then an Ati plate as the outer layer of such 3-layer laminate. For the part, by performing a thickness adjustment process to reduce or increase the thickness, the thickness composition ratio of the Ti thin plate and the Al thin plate becomes a predetermined TiAl intermetallic compound composition ratio in terms of atomic ratio, and , the lamination form of the Ti-Al composite laminate is a three-layer material with a Ti thin plate as the core and an Al thin plate as the outer layer as a reference material, and a plurality of Ti-^1 laminates with a predetermined plate thickness composition ratio. , by further stacking and clad rolling to obtain a multilayer Ti-Al composite laminate, and for the Ti-Al composite laminate before diffusion heat treatment, the average thickness of each layer of the laminate is determined as follows: The thickness should be 20 μm or less in either the state or the state in which the layer is further cold rolled after lamination, and the Al thin plate should contain Si or Mn in an atomic ratio of 1 to 15.
% alone or in combination, and furthermore, Si
, Mn, Fe, B, and other unavoidable impurity elements are added in a total range of 0.01 to 15%.

Note that the Ti and A1 foil plate lamination methods include cold or warm clad rolling, wet or dry plating,
Existing film forming techniques such as CVD and PVD can be used alone or in combination.

[Function] The idea of this invention is based on the process of forming a TiAl intermetallic compound between a Ti thin plate and an Al thin plate in a processing time within an industrially applicable range and having a healthy structure suitable for practical use. The laminated material is manufactured using reaction-diffusion technology.

To this end, the present invention aims to shorten the diffusion distance of Ti and Al as much as possible, to facilitate the multilayer stacking of Ti and Al, and to make the thickness composition ratio of the Ti-Al multilayer laminate (target TiAl intermetallic compound It became necessary to solve the problem of enabling subtle adjustment of (corresponding to the composition of)

First, shortening the above-mentioned diffusion distance is specifically achieved by reducing the thickness of one layer of the multilayer laminate. By reducing the thickness of each layer of the laminate in this manner, the diffusion reaction between Ti and Al can be completed in a short time. Further, when each layer is thin in this way, the amount of mass transfer at the reaction interface is reduced, so that the occurrence of defects such as Kirkendall voids accompanying diffusion can be suppressed. As will be described in detail later, experiments have shown that this objective can be almost achieved if the average thickness of the layer is 20 μm or less.

Next, facilitating multilayer stacking is also related to shortening the above-mentioned diffusion distance.

That is, in order to reduce the thickness of one layer of a multilayer laminate, the entire laminate may be thinned by cold rolling after lamination. For example, when obtaining a product with a plate thickness of llff1l, -
If the thickness of the layer is 10 μm, 100 layers are required. However, with such a large number of layers, methods such as plating, vapor deposition, thermal spraying, and ion blating require extremely advanced technology in terms of film formation speed and accuracy of film thickness control, making it difficult for industrial production. It is difficult and costly to do so.

Therefore, the present inventors decided to use a repeated rad rolling method as a method for obtaining such a multilayered laminate material, since it is possible to produce it on an industrial scale. That is, first, 3 of AlTi-Al whose plate thickness composition ratio was adjusted according to the target components.
By repeating the process of creating a multi-layer laminate and further laminating a plurality of layers of this three-layer laminate by clad rolling, it becomes possible to mass-produce the required multi-layer laminate at a sufficiently low cost.

To explain this in more detail, first, A1-Ti
-A three-layer Al laminate is manufactured by clamp rolling or other methods, and its thickness composition ratio is adjusted to match the desired composition. Next, divide this three-layer laminate into three parts, and
The sheets are piled up and clad rolled.

The number of laminated layers at this point is Al -Ti-Al (-Al
)'-Ti-Al (-Al) There are seven layers of -Ti-Al. The Al-Al bonding layer is considered as one layer after bonding.

Next, this seven-layer laminated material is divided into three again and subjected to clad rolling, resulting in a total of 19 layers.If the same process is repeated, the number of layers is 55.
It can be layered. In this way, it is possible to obtain the number of laminated layers necessary to manufacture a plate-like product with a thickness of about 1 mm by performing four rounds of clamp rolling. In comparison, all other methods require the same number of lamination steps as the number of laminated layers, and the difference in productivity and cost is obvious. However, in order to obtain a good crimped state by clad rolling, rolling must be performed at a reduction ratio of 30 to 40% or more, which is a fairly difficult rolling technique. In particular, when clamp rolling is repeated many times as in the present invention, it becomes more difficult to control the shape. However, in Al--Al clamp rolling, a sufficiently strong crimp can be obtained by rolling at a low rolling reduction of about 10 to 20% due to the mechanical properties of Al. Therefore, if the three-layer laminated material that is the initial reference material is made of Ti as the core and Al as both outer layers, then when clad rolling is repeated, Al will always be the outermost layer and Al-Al clad rolling will occur. This process is not particularly difficult compared to normal clad rolling.

Further, in the three-layer reference material, another effect of using Al as the outer layer is that the thickness composition ratio can be easily adjusted. In other words. The TiAl intermetallic compound, like many other intermetallic compounds, has material properties that are very sensitive to composition. The deformability, which is the biggest bottleneck in the practical application of TiAl intermetallic compounds, is also greatly affected by the composition, and when Ti is around 50 at% A1, ductility may or may not appear with just a 0.1% change in composition. be. Assuming that the thickness of the three-layer laminate is 11 m1, a composition variation of 0.1% roughly corresponds to a variation of 1 μm in the thickness of the Al or Ti plate.

In the present invention, as a method for adjusting the composition ratio of Al and Ti, a method is used in which the composition ratio of plate thickness is adjusted when three layers are first laminated by clad rolling, plating, etc. however,
In reality, it is impossible to achieve an accuracy of ±1 μm only by adjusting during lamination. For example, in the case of clad rolling, the plate thickness composition ratio is almost determined by the thickness of each material used in clad rolling, so considering the control accuracy of plate thickness using current rolling technology, control of ±5 μm is possible. This is the limit. Therefore, in order to control the composition within ±0.1%, it is necessary to measure the plate thickness composition ratio after cladding and then adjust the deviation from the target value by some method.

The method is to compensate for the deficiency of either Al or Ti by dry or wet plating, vapor deposition, etc., or to reduce the excess by chemical or electrolytic corrosion, mechanical polishing, grinding, etc. This allows for fine adjustment of the components. Regarding such treatment, when comparing Al and Ti, both methods have industrially established technology for Al and are easily applicable, but for Ti, chemical corrosion and mechanical With the exception of polishing and grinding, all of these methods are impossible or require highly advanced technology, making them difficult to apply. Therefore, in the manufacturing method according to the present invention, it was decided to use a clad material with A1 as the outer layer as the reference material,
It can also be said that this made it possible for the first time to adjust the components within ±0.1%.

Furthermore, an effect of using Ti as the core material and Al as the outer layer material is that the Ti phase is prevented from oxidizing. Ti is an extremely stable element at room temperature, but at temperatures above 500°C it reacts violently with oxygen, and a large amount of oxygen enters the material as a solid solution to a depth of several micrometers to several tens of micrometers. . In the normal manufacturing process of Ti products, this kind of surface oxidation layer that occurs during hot rolling and intermediate annealing is removed by pickling and mechanical grinding.
In the case where the TiO layer thickness itself has a large effect on the composition adjustment as in the present invention, such a drastic change in the thickness is not preferable. When TiAl becomes an intermetallic compound, T
Since it precipitates as an oxide of i or Al, it is unfavorable from the viewpoint of the soundness of the structure. Of course, it is possible to prevent oxidation using methods such as bright annealing, but this Ti
In this case, a high vacuum of 10-'torr or more is required, and even when an argon atmosphere is used, annealing in that atmosphere is performed with the surface covered with clean Ti chips. Without it, it is said to be difficult to maintain metallic luster. On the other hand, Al forms a strong protective alumina film on the surface, so it is less likely to oxidize during annealing.
Further, unlike Ti, oxygen does not become a solid solution inside the material. Therefore, the oxidation loss during intermediate annealing is small and the composition does not change significantly, and there is no possibility that a large amount of oxygen will be solidly dissolved in the material and produce oxides, so the thickness composition ratio after clad rolling will change. can be almost completely prevented.

Next, regarding the optimal lamination conditions in this invention, according to experiments conducted by the present inventors, in order to obtain a homogeneous intermetallic compound (alloy) with a diffusion heat treatment of about 10 hours, Al
It is necessary that the average thickness of each layer of the i-plate and the Ti thin plate be 20 μm or less. Furthermore, it has been found that in order to obtain a healthy structure free of defects such as voids, it is more preferable to set the average thickness to 10 μm or less. Therefore, the number of laminated layers is determined by dividing the desired product board thickness by 20 μm to 10 μm. For example, in order to obtain a board with a thickness of one layer, the number of laminated layers may be 50 to 100. Note that the number of laminated layers is also related to heat treatment and rolling. That is, in the present invention,
With a short heat treatment of about 10 hours and only annealing,
The first goal is to obtain a homogeneous and healthy organization. In this regard, even if the average layer thickness of the laminated material is thick, if heat treatment is performed for a sufficiently long time and rolling is performed to remove defects such as voids that occur during the heat treatment, the material will have almost the same quality as one with a thin layer thickness. It is possible to obtain the product. In this sense, the regulation of the average layer thickness is not essential, and it is possible to produce a desired TiAl intermetallic compound depending on the subsequent processing.

Next, conditions for diffusion heat treatment for obtaining a desired TiAl intermetallic compound from the above-described laminate will be explained. This diffusion heat treatment is performed at a temperature of 400° C. or higher and 1460° C. or lower for 1 second to 100 hours. The reason why we limited the lower limit of temperature to 400℃ is because in the lower temperature range, Ti and Al
This is because the rate of interdiffusion between the two is extremely slow, and a sufficiently homogeneous alloy structure cannot be obtained even after heat treatment for about 10,000 hours.

Also, the upper limit of this diffusion heat treatment temperature was set at 1460°C. This is because the melting point of the TiAl intermetallic compound is 1460° C., so heat treatment at a temperature higher than that is meaningless.

For example, the lower limit of the heat treatment time is set to 1 second for Al and Ti.
According to the phase diagram of the binary system, 660, which is the melting point of pure Al,
``At temperatures above 1350°C, a liquid phase always occurs on the Al-rich side of the TiAl composition, so diffusion through the liquid phase at temperatures exceeding 1350°C requires a very short soaking time of about 1 second. But it is enough.The upper limit of time is 1
o.

The reason why the time is set is because, although heat treatment exceeding this time is of course possible, it is not industrially practical in terms of productivity. Furthermore, since heat treatment for an unnecessarily long time generally causes problems such as oxidation or defects in the plate shape, it is common to aim for a heat treatment time as short as possible.

In actual operation, it is desirable to combine several types of temperature and time within the range of the above heat treatment conditions depending on the average layer thickness of the laminate to be subjected to heat treatment. Note that the heat treatment time specified here is the soaking time.
It does not include the time required for temperature rise and cooling in the furnace before and after that.

In addition, in the present invention, when Mn and/or Si are further added as additional elements to TiAl, Mn can improve room temperature ductility, and Si can improve high temperature oxidation resistance. These additive elements are added to Ti or A before lamination.
It is sufficient to add a predetermined amount as an alloying element to the material of l.

As explained above, according to the present invention, a thin plate-like product of TiAl intermetallic compound having a practically sound structure and a targeted composition can be manufactured within an industrially applicable processing time. be able to.

〔Example〕

(1) Below, Ti 50. Oat%-Ni 50. O
An example in which a plate material of at% TiAl intermetallic compound was manufactured will be described.

a, pure tin with plate width 200+ma and plate thickness 0.50+ma
An Al-Ti-Al three-layer clad plate was produced by cold clad rolling using the plate and two pure Aim plates of the same width and thickness of 0.30 cm. The plate thickness after clad rolling is 0.8
It became 2 Peng. The thickness composition of Ti and A1 in the clad plate was 40 layers of TiO, and the total thickness of the A12 layer was 0.42 layers.

Converting this plate thickness composition ratio to at% is 52.72 at
%A1.

b6 The above three-layer clad plate was clad-rolled again and cold-rolled to a thickness of 0.50 mm to adjust the plate thickness in order to further laminate the plate into multiple layers. Thereafter, the obtained laminate was subjected to intermediate softening annealing at 600° C. for 10 minutes in an argon atmosphere.

The plate thickness composition of Ti and Al of the annealed plate is Ti 0.
The total of 244 cabinets and A12 layer was 0.256 cabinets, and the thickness composition ratio remained unchanged.

C1 The composition of the final product for this annealed plate is 50at%
A process was performed to remove excess A1 so that A1 was obtained.

The treatment was performed by etching the A1 surface with a 4% Na0FI aqueous solution. Adjustments were made by converting the excess Al into weight and measuring the corrosion loss from time to time. When the thickness structure of the plate after treatment was measured, Ti was 0.244 mm, while Al was 0 in total for the two layers.
．． It is 230m, which is 50.03at%^l in at% conversion.
Met.

60 Next, the above laminate was slit into four strips each having a width of 50 cm. After degreasing this, clad rolling was performed again to obtain a clad plate having a total of 9 layers of Ti thin plates and Al thin plates.

The thickness after cladding was 1.5-.

The clad plate produced in steps e and d was cold rolled to a temperature of 0.50°C, then divided into three parts in the length direction, heated to 600°C,
Intermediate softening annealing was performed for 10 minutes.

f, These three plates are clad-rolled again to form Ti and A1.
A clad material having a total of 25 layers was obtained. It was then cold rolled to a length of 0.25 m. Therefore, Ti and A in this material
The average layer thickness of L was 10 μl.

g. When this material was heat treated at 600°C for 4 hours in an argon atmosphere, a Ti-Al solid solution was formed. TiAl and T
A layered structure consisting of iAh was observed, and T
It was confirmed that alloying of i and A1 was progressing.

h. When this material was further heat-treated at 1000° C. for 110 hours in an argon atmosphere, it was confirmed that a TiAl single layer structure had been obtained.

(2) The same experiment as in Example (1) above was conducted by changing the reaction-diffusion heat treatment conditions.

a9g, the material obtained in step was further heat treated at 2400°C for 1 minute in an argon atmosphere. It was confirmed that a TiAl single layer structure was obtained.

〔Effect of the invention〕

As explained above, according to the manufacturing method of the present invention, a thin plate-like product of TiAl intermetallic compound, which has been difficult in the past, can be produced simply by using Ti without going through the melting and casting process.

It can be manufactured industrially and at low cost by a simple method of subjecting a laminated material of each thin Al plate to diffusion heat treatment.

Patent applicant: Nippon Yakin Kogyo Co., Ltd. Agent Patent Attorney Junzo Ogawa Patent attorney Morio Nakamura

Claims (7)

[Claims] 1. TiA, in which the composition of the intermetallic compound obtained by thermally diffusing an alternately laminated material of Ti thin plates and Al thin plates is determined in proportion to the thickness of these thin plates and the number of laminated layers.
l Intermetallic compound plate material. 2. When producing a TiAl intermetallic compound, the thickness of each plate is adjusted so that the composition of the TiAl intermetallic compound to be produced matches the composition of the TiAl intermetallic compound to be produced in terms of atomic ratio. By adjusting the ratio, the Ti-Al composite laminate thus obtained was heated to 400°C or higher.
A method for producing a TiAl intermetallic compound plate material, comprising performing diffusion heat treatment at a temperature of 460° C. or lower for 1 second to 100 hours. 3. In the manufacturing method according to claim 2, the lamination form of the Ti-Al composite laminate is determined by using a three-layer laminate having a Ti thin plate as a core and an Al thin plate as an outer layer as a reference material, and then using such a three-layer laminate as a reference material. By performing a thickness adjustment process to reduce or increase the thickness of the outer Al thin plate, the thickness composition ratio of the Ti thin plate and Al thin plate can be adjusted to a predetermined T in terms of atomic ratio.
A method for producing a TiAl intermetallic compound plate material, characterized in that the composition ratio of the iAl intermetallic compound is adjusted. 4. In the manufacturing method according to claim 2, the lamination form of the Ti-Al composite laminate is set to a predetermined plate thickness composition ratio using a three-layer laminate having a Ti thin plate as a core and an Al thin plate as an outer layer as a reference material. By further stacking multiple sheets of Ti-Al laminate material and performing clad rolling, a multilayer Ti-Al
A method for manufacturing a TiAl intermetallic compound plate material, characterized in that it is made into a composite laminate material. 5. Regarding the Ti-Al composite laminate before diffusion heat treatment obtained under the manufacturing method according to any one of claims 2, 3, or 4, the average thickness of each layer of the laminate is
A method for producing a TiAl intermetallic compound plate material, characterized in that the thickness is 20 μm or less in either the laminated state or in the state in which the laminated material is further cold-rolled. 6. It is characterized by adding Si or Mn alone or in combination in an atomic ratio of 1 to 15% to the Al thin plate used in the manufacturing method according to any one of claims 2, 3, 4, or 5. A method for producing a TiAl intermetallic compound plate material. 7. TiAl is characterized in that Si, Mn, Fe, B, and other unavoidably contained impurity elements are added in a total range of 0.01 to 15% in the material of the Ti thin plate and Al thin plate used in the above manufacturing method. Method for manufacturing intermetallic compound plate material.