JPH08104933A - Titanium aluminide base composite material - Google Patents

Abstract

PURPOSE: To obtain a heat resistant high strength titanium aluminide base composite material excellent in compatibility of the reinforcing material with the matrix by using tungsten fibers as a reinforcing material and γ-TiAl as a matrix. CONSTITUTION: Tungsten fibers as a reinforcing material are incorporated into γ-TiAl as a matrix preferably by 5-60% to obtain the objective titanium aluminide base composite material. The tungsten fibers are, e.g. fibers contg. ThO2 , HfC, etc., in pure tungsten. The TiAl is an intermetallic compd. Since the tungsten fibers are excellent in compatibility with the γ-TiAl, the objective sound composite material is obtd. by combination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant and high-strength type titanium aluminide matrix composite material applied to hypersonic aircraft, aerospace equipment engines and prime movers.

[0002]

2. Description of the Related Art Heretofore, attention has been paid to the light weight and heat resistance of γ-type TiAl, and a lot of composite materials using it as a matrix have been developed. Al ₂ O ₃ fibers and SiC-based fibers are mainly used as the reinforcing fibers of the composite material, there is no one using W fibers, and no one has succeeded in forming a composite of these fibers and a matrix.

[0003]

In the case of a composite material using γ-type TiAl (intermetallic compound) as a matrix, it is excessive at the interface between the fiber of the reinforcing material and the γ-type TiAl of the matrix during its composite molding or use at high temperature. Occurs. As a result, it is not possible to obtain a sound composite material in which the fiber is deteriorated or a brittle reaction product phase is generated at the interface to cause cracks in the interface between the fiber and the matrix or in the matrix. It is said that the compatibility between the fiber and the matrix is poor because the interface reaction excessively occurs at the interface between the fiber and the matrix and a sound composite material (composite molded body) cannot be obtained.

Therefore, in order to obtain a sound composite material, it is necessary to select a reinforcing fiber having excellent compatibility with the γ type TiAl of the matrix. Conventionally, SiC is the most suitable fiber for γ-type TiAl matrix.
Fibers have mainly been used as reinforcements, and trial research has been conducted. However, as shown in the micrograph (magnification: 100 times) of FIG. 3 showing the cross-sectional microstructure of the metal and fiber of the composite molded body, the SiC-based fiber (circular portion in FIG. 2) and γ-type TiAl (in FIG. 2) The whitish part) In the composite molded body,
A crack (black curve part) starting from the interface propagates in a matrix and does not form a sound composite material. Further, the EPMA analysis result of the interface between the fiber and the matrix is shown in FIG. 4. At this interface, Ti and Al, which are the constituent elements of the matrix, are diffused in the carbon layer on the fiber surface, and the carbon on the fiber surface is It can be seen that are dispersed in the matrix. Further, an X-ray diffraction image of the molded body is shown in FIG. 5. The reaction product at this interface is mainly TiC, which indicates that the interfacial reaction is TiC formation reaction between Ti in the matrix and carbon on the fiber surface. It turns out to be the Lord.

From the above, interfacial reaction occurs excessively in the composite material of SiC fiber and γ-type TiAl, and an embrittlement phase (TiC is brittle) occurs at the interface. That is, the chemical compatibility is poor. Therefore, the molded body (composite material) is cracked and a sound molded body cannot be manufactured.

In view of the above-mentioned state of the art, the present invention aims to provide a titanium aluminide-based composite material having excellent compatibility with γ-type TiAl of the matrix.

[0007]

In order to find a reinforcing fiber having excellent compatibility with γ-type TiAl, γ-type TiAl
The composite molding (diffusion bonding) test of various fibers and γ-type TiAl was performed at the composite molding (diffusion bonding) temperature, molding time, and molding pressure. As a result, it has been found that the tungsten fiber has high tensile strength at high temperature and has little interfacial reaction with γ-type TiAl and excellent compatibility, and the present invention has been completed based on this finding.

That is, the present invention is a titanium aluminide matrix composite material characterized by using tungsten fiber as a reinforcing material and γ type TiAl as a matrix.

The tungsten fiber content (Vf) in the γ-type TiAl of the present invention is preferably in the range of 5 to 60%.

The tungsten fibers used in the present invention include pure tungsten (W), ThO ₂ , and HfC.
Such as a fiber containing Wo-Re alloy with ThO ₂ , Hf
Al ₂ O _{3 is} added to the fibers and pure tungsten containing C etc.
Examples include doped tungsten fibers containing the above.

TiAl in the present invention is an intermetallic compound, and includes Ti ₃ Al (α2), TiAl (γ) and TiA.
There are three types of l _3, of which the crystal structure of the TiAl L
It is of the I ₀ type and is called γTiAl.
However, γTiAl has drawbacks such as poor ductility at room temperature and insufficient high temperature strength, and various elements such as Nb, Cr, Mn, W and Ta are added to improve these drawbacks. Further, the γTiAl single phase is practically hardly used, and normally α
2 (having a DO ₁₉ type crystal structure) and β phase (b, C, C
Alternatively, it has a BCT crystal structure. This is not an intermetallic compound), but most of them are also mixed. Generally γT
The Al content of iAl is 43 to 53% (atomic%).

Therefore, the TiAl used in the present invention is purposely specified as γ-type TiAl, not γTiAl which is metallurgical. Therefore, the γ-type TiAl in the present invention is a titanium aluminide containing γTiAl as a main component, and is defined as containing the above-mentioned various elements and compounds.

[0013]

Since tungsten fiber has excellent compatibility with γ-type TiAl, a sound composite material can be obtained by compounding.

[0014]

Example A doped tungsten fiber having a diameter of 0.1 mm (trademark: AW Tokyo Tungsten Co., Ltd.) having a diameter of 500 m is used.
A pitch of about 0.15 mm is wound around a drum of m, and a Ti-46Al-2Cr-2Nb (at
MIC%) PREP powder (powder made by plasma electrode rotation method) is sprayed by low pressure plasma spraying to manufacture a sprayed preform. Ti-46Al-2Cr-2Nb
Table 1 shows an example of thermal spraying conditions for thermal spraying.

[0015]

[Table 1]

Next, the above-mentioned thermal spray preform was removed from the drum and four layers were laminated, and both surfaces of the laminate were Ti-26.
Al-11Nb (atomic%: This is Ti ₃ A
It is sandwiched with a sheet material (thickness: about 100 μm) (trademark: ALPHA-2, which is a type I α2). The coating with this sheet material is to prevent the fibers of the laminate of the thermal spray preform from being exposed. The Ti ₃ Al type α2 was used because the γ type TiAl had a problem in room temperature ductility as described above, and it was difficult to obtain a sheet material, so that it was not available. This sandwiched laminate was heated at a temperature of 1050 ° C. and a pressure of 1500 at.
m, time: 120 minutes for HIP, and composited and integrated.

FIG. 1 shows the molded body (composite material) of FIG.
Cross section microstructure (similar to). As can be seen from FIG. 1, a sound molded body (composite material) having no crack in the matrix was obtained. Further, the EPMA analysis result of the interface is shown in FIG. 2, and it can be seen from this that the interface of the composite material of the present invention has no interface reaction or is extremely small. This molded body (composite material) is 100
It shows a high value of 57 kgf / mm ² at 0 ° C, and the strengthening by the tungsten fiber is clear (the strength of γ-type TiAl at 1000 ° C is about 20 kgf / mm ² ).

[0018]

EFFECTS OF THE INVENTION Tungsten fiber has excellent compatibility with γ-type TiAl and therefore does not cause excessive interfacial reaction.
A sound molded body (composite material) without cracks can be obtained.

[Brief description of drawings]

FIG. 1 is a W fiber reinforced γ type TiA according to an embodiment of the present invention.
The micrograph which shows the cross-section microstructure of the metal and fiber of a l-base composite material.

FIG. 2 is an EPMA line analysis chart at a fiber / matrix interface of the composite material of the above-described embodiment of the present invention.

FIG. 3 is a micrograph showing a cross-sectional microstructure of a metal and a fiber of a conventional SiC-based fiber-reinforced γ-type TiAl-based composite material.

FIG. 4 is an EPMA line analysis chart at the fiber / matrix interface of the conventional composite material.

FIG. 5 is a chart showing an X-ray diffraction image of the conventional composite material.

Claims (1)

[Claims] 1. A titanium aluminide-based composite material comprising tungsten fiber as a reinforcing material and γ-type TiAl as a matrix.