JPH0250933A - Ti-al series intermetallic compound containing p and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture the title compound having high ductility at ordinary temp. and having high temp. oxidizing resistance by regurating its crystal structure to an L10 type regular structure having specific compsn. contg. P. CONSTITUTION:To improve the high ductility at ordinary temp. and high temp. oxidizing resistance of a Ti-Al series intermetaillic compound suitable for a high temp. heat-resistant material, its structure is regulated to L10 type crystal one constituted of 40 to 50atom% Ti and 60 to 50atom% Al and contg. 100wt. ppm P. The Ti amt. is regulated to the range of 40 to 50atom% in order to obtain the Ti-Al intermetallic compound as a single phase by homogeneous annealing without depositing other phases. By the addition of 100 to 1000wt.ppm, P, stacking fault energy is lowered and twinning organization at the time of plastic deformation is activated to improve the ductility at ordinary temp. and the growth of Ti oxide is stopped to improve the high temp. oxidizing resistance; at this time, P should be uniformly dispersed over the whole of the sample without the generation of segregation. In such a manner, the Ti-Al series inermetallic compound having high ductility at ordinary temp. and furthermore retaining high temp. oxidizing resistance can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to high-temperature heat-resistant strength materials (aircraft turbine engines,
gas turbines for power generation, automobile engines, high-speed rotating bodies)
The present invention relates to a P-added Ti-/V-based gold intermetallic compound that has improved room-temperature ductility and high-temperature oxidation resistance, and a method for producing the same.

[Conventional technology]

Ti-Al intermetallic compounds have the highest specific strength at high temperatures among metal materials, have high corrosion resistance, and are lightweight materials. Metallurgical Trans
action, Vo10 68 (1975) p, 19
91, it was reported that a high temperature strength of 40 kg/- was obtained at 800°C. Therefore, by utilizing these properties, TiAl-based intermetallic compounds are used for gas turbine parts,
It has been considered suitable for application to automobile engine valves and pistons, high-temperature ties, bearing parts, etc.

Ti-N intermetallic compounds have a certain composition range on the phase diagram, and have an L10 type structure (basically a face-centered tetragonal structure, but It becomes a single phase structure in which Ti layers and IVO layers are arranged alternately in the 001) direction. For this reason, an abnormal strengthening phenomenon has been discovered in which the strength increases with increasing temperature in the single crystal state. It is known that polycrystalline materials do not lose their strength even at high temperatures. However, the drawback of Ti-Al intermetallic compounds is that their ductility is low from room temperature to around 700°C, and the compressibility was 0.4% at room temperature and about 1.1% at 700°C.

The difficulty in developing Ti-Al intermetallic compounds as practical materials was how to ensure room-temperature ductility, but it was discovered that adding Mn was effective (Japanese Patent Laid-Open No. 62-21
Publication No. 5). However, it has been reported that Mn addition has the disadvantage of deteriorating high-temperature oxidation resistance (Tsurumi et al., Japan Institute of Metals Symposium - Plastic Deformation of Ordered Alloys and Intermetallic Compounds - July 16, 1986, p. 13). There is.

[Problem to be solved by the invention]

Ti-/V-based gold intermetallic compounds are lightweight, have a high heat resistance, and have high corrosion resistance, so they are suitable for Kubin blades that are used at high temperatures, but they have low ductility at room temperature (compressibility of 0.4 %), making it difficult to form by rolling, forging, etc., and also being unreliable in terms of safety at room temperature, hindering its practical application.

An object of the present invention is to develop a Ti-A7-based gold metal compound which is a high-temperature heat-resistant strength material that overcomes these problems.

[Failure to solve the problem]

The present invention solves the above problems and
atomic%, A75Q ~ 50 atomic%, P10o ~
To provide a Ti-Al based intermetallic compound containing 1000wtppm and having a crystal structure having an L10 regular structure, which has high room temperature ductility and does not lose high temperature oxidation resistance, and by melting a raw material having the above composition in an inert gas atmosphere. , which is produced by performing regular annealing after solidification
A method for manufacturing an Al-based intermetallic compound material is provided.

The Ti content was set in the range of 40 to 50 atomic % because the composition range of the single phase of the TiN-based intermetallic compound has this range, and with this composition, uniform annealing is possible without precipitating other phases. This is because a Ti-At'-based intermetallic compound can be obtained in a single phase.

The reason why P is added in an amount of 100 to 1000 wtppm is to lower the stacking fault energy, activate the twin deformation mechanism during plastic deformation, and improve room temperature ductility.
The purpose is to stop the growth of Ti oxide and improve high-temperature oxidation resistance, and in this case, P needs to be uniformly dispersed throughout the sample without segregation.

The P-containing Ti-jV gold intermetallic compound prepared in this way has a yield of nearly 30% at room temperature and nearly 40% at 600°C (
It shows a compressibility of 100°C, and improves the low ductility from room temperature to around 700°C, which is a problem with Ti-Al intermetallic compounds.

The method for producing the P-added Ti-Al intermetallic compound of the present invention includes 40 to 50 atom% of Ti and 21 to 50 atom% of A1'5Q to 50 atom%.
00 to 1000wtppm was added in a vacuum (
10-"torr or higher) in an environment substituted with an Ar gas atmosphere, and in order to avoid reaction with the crucible.
After heating to 400°C to 1500°C and melting and solidifying,
For ordering, ordering annealing is performed in the same inert gas atmosphere as described above. This is because Ti and N must be diffused at high temperatures in order to obtain the L lo type structure. The temperature during ordering annealing is T at 800°C or higher.
The purpose can be achieved in the single phase range below the melting point of the i-Al intermetallic compound, but among these, 900 to 11
A temperature range of 00°C is preferred.

Uniform diffusion of P is also satisfied under this condition. Further, the heating time is short at high temperatures because time is required for atomic diffusion for ordering, but it is desirable to set it to 24 hours or more in order to achieve complete ordering. Obtained P
Using a word X-ray diffractometer in which the added Ti-Al intermetallic compound is ordered, each peak is Ti -
It is sufficient to confirm that it corresponds to the L10 type structure of an Al-based intermetallic compound.

Next, the reason for the improvement in room temperature ductility of the P-added Ti-Al intermetallic compound of the present invention will be explained. It is believed that the addition of the third element P reduces the stacking fault energy of the Ti-Al intermetallic compound. This has been confirmed by electron microscopy and in-situ ultra-high-voltage electron microscopy observations due to the activation of twin deformation, especially cross twinning, in the deformation mechanism. The inventors conducted Con1-Last experiments using an electron microscope on this alloy and found that during plastic deformation, these crossed twins do not pile up dislocations on the twin boundaries, but instead form slip dislocations through a dislocation reaction and spread. We have confirmed that performance has been improved.

High-temperature oxidation resistance is improved by the oxide film formed on the material surface that prevents oxygen from permeating. In the case of TiAl, the oxygen vacancy in the Ti0z-x layer formed on the sample surface
It is thought that oxidation progresses due to the diffusion of O through the oxygen νa
It is necessary to suppress the spread of 0 by eliminating the ``cancy''.

The reason why the oxidation resistance of the alloy of the present invention is improved is that P, which is an element of the Vb group, has a valence of 5, which is larger than the number of valence electrons of TI (4).
This is thought to be because the oxygen vacancy in the □-8 layer is reduced, the inward diffusion of oxygen is suppressed, and the growth of the oxide layer 'rio2-X, which is formed in Ti7V in a high-temperature oxidizing atmosphere, is stopped.

〔Example〕

Next, examples of the present invention will be shown.

Sponge Ti50atm% (63
, 9 wt%), purity 99.99 wt% IV50a
tm% (36.0wt%) with 500wtppm of P added thereto was melted in a vacuum melting furnace,
orr or more) and heated to 1500°C in an environment substituted with an Ar gas atmosphere to melt and solidify, and then ordering annealing was performed in the same inert gas atmosphere as in the previous period for ordering. The purpose can be achieved as long as the temperature during ordering annealing is in a single phase range of 800°C or higher and below the melting point of the Ti-M-based intermetallic compound, but among these, 1000 °C
A temperature range of °C was used. Further, the heating time was set to 72 hours to ensure complete regularization. The obtained P-added Ti-/V-based gold intermetallic compound is ordered.
Using a line diffractometer, each peak was detected as Ti-Al.
It was confirmed that it corresponds to the LL type structure of the intermetallic compound.

FIG. 1 shows a stress-strain curve showing the results of a cold compression test using a 5φ×5 mm sample cut out from the sample thus obtained by electrical discharge machining. From the figure, it can be seen that the addition of P significantly improves the room temperature ductility compared to the TiA/sample.

For further comparison, Table 1 shows the amounts of Ti/V and P added.
Table 2 shows the yield strength and ductility of V when compressed at room temperature.

The sample of the present invention was found to have significantly improved yield point under compressive deformation and room temperature compressibility compared to TiAZ without the addition of a third element. Even when compared with the 4wt% Mn-added material, the yield point and room temperature compressibility showed almost the same performance (Figure 2). Regarding oxidation resistance, Mn addition improves oxidation resistance, especially Weig
ht Ga1n decreases compared to T i A/ without the addition of a third element, whereas Weight Ga1 in the P-added material decreases.
It was observed that the n value was low, and the oxidation resistance was significantly improved in the P addition amount range of 100 to 1200 atomic ppm (Figure 3).

The above results are shown in Table 3. Table 3 shows the yield strength and ductility of TiA1 and third element-added Ti1V in compression at room temperature to high temperature.
Each numerical value of the high temperature oxidation resistance test result (Weight Ga1n) is shown.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a Ti-A/based gold intermetallic compound that has high room-temperature ductility and does not lose high-temperature oxidation resistance.

[Brief explanation of the drawing]

Figure 1 is a stress-strain curve showing the results of a cold compression test using the sample obtained according to the example, and Figure 2 is a TiA
TiAJ with addition of l and third element! Figure 3 shows the yield strength and ductility in compression at room temperature to high temperature.
1V and T i IV high temperature oxidation resistance test results (Weig
ht Ga1n ). ■ 0 mouth ku・■( To N ~ Alarm ψ ≧ (・2 Ilme) q・y, look after 0 mouth ku・厘 ( N edge + me ( ≧ θ size (%) φ 嗟go

Claims (3)

[Claims] (1) A Ti-Al based intermetallic compound consisting of 40 to 50 atomic % of Ti, 60 to 50 atomic % of Al, and containing 100 to 1000 wtppm of P, and whose crystal structure is an L1_0 type ordered structure. (2) A Ti-Al based intermetallic compound having an L1_0 type ordered structure with a room temperature compressibility of 30% or more, consisting of an atomic ratio of 45 to 50 atomic % Ti, 50 to 55 atomic % Al, and containing 100 to 1000 wtppm of P. (3) Ti-Al for high-temperature strength materials characterized by melting and solidifying 40 to 50 at. % of Ti, 60 to 50 at. Method for producing intermetallic compounds.