JPH03267342A - Ni3(si, ti) heat resisting material having good cold ductility - Google Patents

Abstract

PURPOSE:To obtain the Ni3(Si, Ti) heat resisting material having excellent high-temp. strength and good cold ductility by specifying a compsn. consisting of Si, Ti, C, and Ni. CONSTITUTION:This intermetallic compd. Ni3(Si, Ti) based heat resisting material contains 10 to 13atomic% Si, 8 to 10% Ti and 0.01 to 0.5% C and consists of the balance substantially Ni. The material has the excellent high-temp. strength and is improved in the ductility from ordinary temp. to a liquid nitrogen temp. by addition of a proper ratio of C. The environmental embrittlement of the above-mentioned material is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a heat-resistant material that is based on the intermetallic compound Nf3 (Si+Ti) and has excellent high-temperature strength and good room-temperature ductility.

Background technology Traditionally, precipitation-hardening Ni-based heat-resistant alloys have been mainly used as materials for high-temperature, high-load parts such as aircraft engines and industrial gas turbine engines. "Ni3(S
i, Ti)' has started to attract attention.

As shown in Figure 1, the strength properties of N15 (Si, Ti) are significantly higher than those of Hastelloy It can be said that it has. However, on the other hand, the intermetallic compound Ni3(S
i, Ti) has the problem of environmental embrittlement, in which its ductility is extremely reduced at liquid nitrogen temperatures, and its ductility is lower in air than in vacuum, so it has not been widely used as a practical material. This was a major obstacle to opening.

That is, FIG. 2 shows Ll, type intermetallic compound N15 (Si, T
This is a graph showing the relationship between temperature and elongation in (i). As can be seen from Figure 2, ductility in the atmosphere peaks around 500°, and decreases markedly at room temperature. It is clear that almost no elongation will be shown at temperatures around 77'K. Moreover, the second
When compared with the "temperature dependence curve of ductility in vacuum" shown in the figure, it is clear that environmental embrittlement near room temperature is extremely significant.

Therefore, the purpose of the present invention is to find a means to improve the ductility and environmental embrittlement of Ni3 (Si, Ti), an intermetallic compound with excellent high-temperature strength, from room temperature to liquid nitrogen temperature, and to make it practical. Our goal is to provide a rich variety of new high-performance heat-resistant materials.

Means for Solving the Problems> Therefore, in order to achieve the above object, the present inventors conducted numerous experiments and conducted research from various angles, and as a result, they came to the following knowledge. be. That is, (a) The intermetallic compounds Ni3 (Si, Ti), which were previously recognized as not exhibiting sufficient elongation in the temperature range from room temperature to liquid nitrogen temperature, can be improved by adding an appropriate amount of C, an interstitial element. Compared to Ni3 (Si, Ti), the ductility from room temperature to liquid nitrogen temperature is noticeably improved.

(b) Furthermore, by adding an appropriate amount of C, the problem of environmental embrittlement mentioned above is eliminated, and the ductility value from room temperature to liquid nitrogen temperature is equal to or higher than that of Ni 3 (Si + Ti) in vacuum. This will be improved.

The present invention has been made based on the above-mentioned findings, etc., and has the following characteristics: ``The chemical component composition is Si: 10 to 13% (hereinafter, % representing the component ratio is atomic %).

Ti: 8-10%, C: 0.01-0.5
%, and the balance is substantially made of Ni, thereby realizing a heat-resistant material with excellent high-temperature strength and good cold ductility.'' It has characteristics.

Here, in the Ni3 (Si, Tf) base material according to the present invention, the Si content is limited to 10 to 13% and the Ti content is limited to 8 to 10%. This is because if it is out of this range, the realization of L12 becomes unstable and the desired high temperature strength cannot be ensured.

In addition, C is included to improve the ductility and environmental brittleness from room temperature to liquid nitrogen temperature seen in Ni:+ (Si, Ti), but when the content is 0
．． If it is less than 0.01%, the desired effect cannot be ensured.

On the other hand, the solid solubility limit of C is on the order of several tens of ppm, but even if carbides precipitate, as long as the content is within 0.5%, there will be no adverse effect on strength and ductility. , C
The upper limit of the content was set at 0.5%.

Hereinafter, the functions and effects of the present invention will be explained in more detail based on Examples.

<Example> First, for N+3 (Si, Ti), Si: 11%,
Two types of samples were prepared by argon arc melting, with a basic composition of Ti: 9.5% and 0.25% and 0.5% of C, which is an interstitial additive element, added thereto. Next, each obtained ingot was subjected to homogenization annealing at 1323' for 24 hours, and then hot rolling and intermediate annealing were repeated several times to form a plate material. Thereafter, the sample was subjected to a recrystallization heat treatment for 5 hours at 1273', subjected to a tensile test at various temperatures, and the temperature dependence of elongation was investigated in the air.

These results are shown in FIGS. 3 and 4. In addition, in FIGS. 3 and 4, for comparison, N1z (S
The results of investigations regarding i, Ti) in vacuum and in the atmosphere are also listed.

From the results shown in Figures 3 and 4, it is clear that the ductility of Ni3 (Si without carbon) decreases significantly from room temperature to liquid nitrogen temperature, and that the ductility of Ni3 (Si
, Ti), N13 containing 0.25% or 0.5% C (St + Ti) has significantly improved ductility from room temperature to liquid nitrogen temperature, and C-free N1z (St + Ti) in vacuum is significantly improved. It can be confirmed that this material exhibits characteristics superior to those of Si, Ti).

Therefore, it has been found that a material containing an appropriate amount of C in Ni3 (Si, Ti) can be a high-performance heat-resistant material with sufficient practicality.

Summary of Effects> As explained above, the present invention makes it possible to provide a practical heat-resistant material that exhibits extremely excellent high-temperature strength and room-temperature ductility, making a significant contribution to improving the performance of heat-resistant equipment components. It can be expected to bring about extremely useful effects industrially.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between temperature and yield strength of various heat-resistant materials. FIG. 2 is a graph showing the relationship between temperature and elongation of Ni:+(St, Ti). Figure 3 shows N i:I (S i+
T 1 ) and 0.5% C added Ni: + (Si , T
It is a graph showing a comparison of elongation values with material i). Figure 4 shows Ni:+ (Si, Ti
) and a 0.25% C-added N15 (Si, Ti) material in comparison.

Claims (1)

[Claims] It is characterized in that it contains Si: 10 to 13%, Ti: 8 to 10%, and C: 0.01 to 0.5% in atomic %, and the balance consists essentially of Ni. , Ni_3 (Si, Ti) heat-resistant material with good room temperature ductility.