JPS6293332A - Ni alloy - Google Patents

Abstract

PURPOSE:To obtain a high strength and high ductility Ni alloy made chiefly of an L12 type intermetallic compound by specifying a composition consisting of Al, B, Fe, Hf, Zr, and Ni. CONSTITUTION:This Ni alloy has a composition consisting of, by weight, 4X13% Al, <=3% B, 0.005-12% Fe, 0.005-22% Hf and/or 0.005-4% Zr and the balance Ni with inevitable impurities. The alloy is made chiefly of an L12 type intermetallic compound. The alloy has high ductility at ordinary temp. and such a high temp. as >=about 600>=oC and sufficiently high strength, so it is suitable for use as a material for parts of a gas turbine or the like or as a structural material exposed to a high temp. for a long time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention applies to structures that are exposed to high temperatures for long periods of time, such as disks, vanes, nozzles, blades, etc., which are the main parts of gas turbines, jet engines, high-temperature pulp, and high-temperature gas furnaces. Regarding materials.

[Conventional technology]

Ni-based superalloys are used as structural materials that are exposed to high temperatures for long periods of time, such as in gas turbines, jet engines, high-temperature valves, and high-temperature gas furnaces. In the case of this Ni-based superalloy, the high-temperature strength is strengthened by precipitating intermetallic compounds such as the γ' phase [Ni゜(Al, Ti)] by 1% or more.
In addition, the γ phase, which is the matrix phase of Ni, provides ductility and toughness. However, in the case of this type of material, since the matrix phase is a Ni phase, there is a fundamental drawback that the strength decreases significantly at high temperatures.

On the other hand, the intermetallic compound Ni3Al, which is the main reinforcing phase in Ni-based superalloys, has the unique property of increasing its strength as the temperature increases, but it has no ductility or toughness, and even when subjected to a tensile test, it does not elongate. It is almost zero and cannot be used as a structural material at all, and the use of this material as a structural material for high temperatures has been a major challenge for a long time.

Recently, it has been proposed that ductility at room temperature can be improved by adding 3% or less of B to Ni5Al. (Unexamined Japanese Patent Publication No. 55-5834/) L, Kaji, and B-added N
i, Al has sufficient ductility at or near room temperature, but at high temperatures, especially above 600°C, the ductility is almost zero, and the strength at high temperatures is also insufficient.

[Problem that the invention seeks to solve]

The intermetallic compound Ni5Al has no ductility at all except in single crystal form. Furthermore, when B is added as proposed above, the ductility at room temperature can be improved, but sufficient ductility cannot be obtained at high temperatures, particularly at temperatures above 600°C.

Further, although the strength has a positive temperature dependence in that the strength increases as the temperature rises, the absolute strength at high temperatures is not necessarily sufficient.

The present invention aims to provide a Ni-based alloy that has high ductility and sufficiently high strength at high temperatures and is composed mostly of T-L type intermetallic compounds of Ni and Al systems.

[Failure to solve the problem]

In the present invention, Al4 to 13 wt% and B5 wt% or less.

Contains Fe 0.005-12wt% and Hfα00
5-22 wt% or Zr 0. n n 5~4 w
The alloy is a high-strength and high-ductility Ni-based alloy containing t% in combination or alone, the balance depending on the composition of Ni and unavoidable impurities, and most of the alloy is composed of L-type intermetallic compounds.

The present inventors have discovered that by combining various additive elements to a Ni3Al alloy, a Ni-based alloy can be obtained that is highly ductile not only at room temperature but also at high temperatures, and has much higher high-temperature strength than Ni3Al.

The reasons for limiting the composition of the alloy of the present invention will be described below.

Al: Al is an essential element for forming L-type intermetallic compounds, and its necessary composition range is 4 to 13.
It is wt%. If the amount is less than 4 wt%, Al will form a solid solution in the matrix and will not form an L-type intermetallic compound. Sweet, 13wt%
Although an L-type structure can be formed even if it exceeds the above, sufficient ductility cannot be obtained. Within this range, the preferred range is 6 to 13 wt%,
A particularly preferred range is 8 to 15 wt%.

B: B is effective in improving ductility at and near room temperature. However, even if it exceeds 3%, sufficient ductility cannot be obtained and on the contrary, it becomes brittle. Within this range, the preferred range is 0.01 to 0.3
yt%, particularly preferred range is 0.03 to 0.1wt%
It is.

F'e: Fe greatly improves the ductility of Ni3Al and Ni. However, if it is less than 0.0115 wt%, the effect is not sufficient. In addition, even if it exceeds 12 wt%, Ni
, the positive temperature dependence of the strength of Al is weakened and sufficient strength at high temperatures cannot be obtained. Within this range, the preferred range is 1 to
12 wt%, particularly preferred range is 3 to 12 wt%.

Hf: Greatly improves the strength of Ni and Al. 0.0
The effect is not sufficient if it is less than 0.05 wt%, and 22 wt%
Even if added in excess of Ni, AI! It is not dissolved in solid solution and has no effect on improving strength. Within this range, the preferred range is 5 to 2
2 vrt%, particularly preferred range is 9 to 18 vrt%
It is.

Zr: Zr is also Ni! It is effective in improving the strength of Al.

0, the effect is not sufficient when OO is less than 5wt% (4w
Even if it is added in excess of t%, it will not be dissolved in Ni3Al and will not be effective in improving the strength. Within this range, the preferred range is 1 to
4 wt%, particularly preferred range is 1.7 to l5 wt
%.

Unavoidable impurities: S and co may be unavoidably mixed, but the former is about 0. There seems to be no problem as long as U 3 wt% or less, and the latter is about 0.5 vrt% or less.

〔Example〕

The present invention will be specifically explained with reference to Examples.

Table 1 shows the components of the alloys tested. The test materials were melted in a vacuum high-frequency melting furnace. After melting the test material 105
A homogenization treatment was performed at 0° C. for 50 hours, and a tensile test was performed.

Table 1, Figure 1 shows the results of a tensile test conducted in the temperature range from room temperature to 900°C. Mu 1 to Cliff 5 of the present invention materials are comparative materials A
6, showing much higher high temperature strength than A7. (Although A4 is omitted in Figure 1, this is because the graph becomes complicated, and it shows the same curve as 41-3 and M5.) Figure 2 shows the tension shown in Figure 1. FIG. 3 is a diagram showing elongation measured in a test. The f1 to f45 materials of the present invention elongate by about 15% even at temperatures above 600°C. On the other hand, comparative materials jI66 and M7 have high ductility at room temperature, but their elongation is zero at temperatures above 600°C.

Although Figure 2 does not show the growth of /I63 and A5, 1. This is because the graph becomes complicated, and A3
and Flat 5 show approximately the same curves as AI, A2, and A4. Also, the elongation of A6 (comparative material) is not shown, but this is because there is no elongation at all from room temperature to high temperature, and it breaks brittle.

〔Effect of the invention〕

Since the material of the present invention has excellent strength and ductility at high temperatures,
It can be applied to major structural materials that are exposed to high temperatures for long periods of time, such as gas turbines, jet engines, high-temperature valves, and high-temperature gas furnaces, making it possible to operate plants at higher temperatures than before, thereby increasing efficiency. be able to.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between test temperature and 0.2% yield strength when a tensile test was conducted on a sample material. FIG. 2 is a diagram showing the relationship between test temperature and elongation when a tensile test is performed on a sample material. Sub-Agents 1) Meifuku Agent Ryo Hagiwara - Sub-Agent Atsuo Anzai ``Test Temperature ('C)'' Figure 2 Test Temperature (°C)

Claims (1)

[Claims] Al4~13wt%, B3wt% or less, Fe0.005
~12wt%, and Hf0.005~22wt%
Or a high-strength and high-ductility Ni-based alloy containing 0.005 to 4 wt% of Zr in combination or alone, the remainder consisting of Ni and unavoidable impurities, and most of the alloy consisting of LI_2 type intermetallic compounds.