JPH0551679A - Tial intermetallic compound having high toughness and ductility - Google Patents

Abstract

PURPOSE:To obtain the intermetallic compound by adding specific amounts of In to the composition of a TiAl intermetallic compound containing specific proportion of Al. CONSTITUTION:This TiAl intermetallic compound is prepared by adding 0.05-3 atomic % In to the composition of a TiAl intermetallic compound consisting of 30-60 atomic % Al and the balance Ti and has superior ductility at ordinary temp. and toughness. When In contents is lower than 0.05 atomic % or exceeds 3 atomic %, the bending strength and bending elongation of the above intermetallic compound are deteriorated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a high toughness ductile TiAl-based intermetallic compound.

[0002]

2. Description of the Related Art TiAl-based intermetallic compounds have been attracting attention as structural materials for engine parts and the like because they are lightweight and have excellent heat resistance.

[0003]

However, the conventional TiAl intermetallic compound has poor workability due to low room temperature ductility, and has poor practicability due to low toughness even when commercialized. There is.

In view of the above, it is an object of the present invention to provide the above TiAl-based intermetallic compound which has an improved metallic structure and is improved in room temperature ductility and toughness by adding a third element.

[0005]

High toughness ductility T according to the present invention
iAl-based intermetallic compound is 30 atomic% or more, 60 atomic%
It is characterized in that 0.05 atomic% or more and 3 atomic% or less of In is added to the TiAl-based intermetallic compound composition containing the following Al and the balance being Ti.

[0006]

EXAMPLE FIG. 1 schematically shows an example of the metallographic structure of a TiAl-based intermetallic compound.
The layered structure (lamella structure) is formed by alternately depositing the Al phase γ and the Ti ₃ Al phase α ₂ , and in the illustrated example, the layered structure portion L is an aggregate. In order to obtain such a metallographic structure, it is necessary to set the Al content to 30 atom% or more and 52 atom% or less in terms of composition.

In this case, the volume fraction V of the Ti ₃ Al phase α ₂ is
By setting f to 0.05% or more and 80% or less, preferably 5% or more and 60% or less, the room temperature ductility of the TiAl-based intermetallic compound can be improved. From the viewpoint of improving room temperature ductility, the average grain size of the layered structure L is 1 μm.
It is desirable that the thickness is m or more and 1000 μm or less.

FIG. 2 schematically shows another example of the metal structure of the TiAl-based intermetallic compound. This metal structure is T
It is composed of a single-phase portion Sγ consisting only of the iAl phase and a layered structure portion L in which TiAl phase γ and Ti ₃ Al phase α ₂ are alternately deposited. In order to obtain such a metallographic structure,
In terms of composition, it is necessary to set the Al content to 45 atom% or more and 60 atom% or less.

In this case, the room temperature ductility of the TiAl-based intermetallic compound can be improved by setting the volume fraction Vf of the layer structure L to 15% or more, preferably 35% or more. From the viewpoint of improving the room temperature ductility, the average grain size of the layered structure portion L is preferably 1 μm or more and 1000 μm or less.

According to the present invention, T containing 30 atomic% or more and 60 atomic% or less of Al that develops the metal structure as described above is contained.
In the composition of the iAl-based intermetallic compound, 0.05 atomic% or more,
3 atomic% or less of In is added to form an In-added TiAl-based intermetallic compound.

Such an intermetallic compound was manufactured by the following method.

First, Ti (sponge titanium) having a purity of 99.5%, Al (aluminum shot) having a purity of 99.99%, and In having a purity of 99.9% were weighed to a target composition to obtain a raw material. .. The composition of this material, in atomic%, is (Ti ₅₃
Al ₄₇ ) _100-x In _x . Then, the material was melted in an Ar atmosphere using a non-consumable arc melting furnace to obtain an ingot. Then heat the ingot to a heating temperature of 15
Heat treatment was performed under the conditions of 73 K and a heating time of 3 hours, and I
An n-added TiAl-based intermetallic compound was obtained.

In the melting step, in order to improve the homogeneity of the intermetallic compound, first, the first melting (melting from the front side)
After doing, turn the ingot over and perform the second melting (melting from the back side) to make two button-shaped ingots,
Then, the two button-shaped ingots were combined, and melting from the front side and melting from the back side were repeated as one cycle to form a 40-g thumb-shaped ingot.

In order to investigate the toughness and room temperature ductility of the In-added TiAl-based intermetallic compound, the following bending test was conducted.

From the above-mentioned intermetallic compound, length 3 mm, width 4 mm,
A test piece having a length of 37 mm was manufactured, and the test piece was subjected to a 4-point bending test (JIS R 1601) at room temperature.
In this test, the crosshead speed was set to 0.5 mm / min, the strain and the rolling load due to the strain gauge attached to the stretch side of the test piece were measured, and the bending strength and bending elongation were determined from these measured values. I asked.

FIG. 3 shows the relationship between the amount of In added and the bending strength. As is clear from FIG. 3, the amount of added In is 0.05
By setting the atomic percentage to 3 atom% or less, I
It is possible to improve the bending strength, and thus the toughness, of the n-added TiAl-based intermetallic compound.

FIG. 4 shows the relationship between the amount of In added and the bending elongation. As is clear from FIG. 4, the amount of added In is 0.05
By setting the atomic percentage to 3 atom% or less, I
The bending elongation of the n-added TiAl-based intermetallic compound, and thus the room temperature ductility, can be improved.

However, if the amount of In added is less than 0.05 atomic% or exceeds 3 atomic%, In-added TiA is added.
Both the bending strength and the bending elongation of the l-based intermetallic compound decrease.

[0019]

According to the present invention, a TiAl intermetallic compound having excellent toughness and ductility can be provided by specifying the Al content and the In content as described above.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a metal structure.

FIG. 2 is an explanatory diagram showing another example of the metal structure.

FIG. 3 is a graph showing the relationship between the amount of In added and the bending strength.

FIG. 4 is a graph showing the relationship between the amount of In added and bending elongation.

Claims (1)

[Claims] 1. Al of 30 atomic% or more and 60 atomic% or less
A high toughness ductile TiAl-based intermetallic compound, characterized in that 0.05 at% or more and 3 at% or less of In is added to a TiAl-based intermetallic compound composition containing Ti and the balance being Ti.