JPS63266036A - Ni based alloy - Google Patents

Abstract

PURPOSE:To produce an Ni based alloy having excellent ductility at the ordinary temp. and high temp. by adding specific ratios of metallic elements such as B, Hf, etc., to the alloy consisted essentially of Ni and Al and formed the structure of Ni3Al as intermetallic compounds. CONSTITUTION:The base metal 7 of the Ni based alloy contg., by atom., 75.4-79% Ni, 7-12% Al, 0.5-4% Hf, <0.5% B, <0.9% C, 4.5-11% Fe or Co and one or more kinds among the elements selected from the group of each <=3% Mo, W, Nb, Ta, Zr and V and having the structure composed mainly of the intermetallic compound Ni3Al is charged to a crucible 6 made of alumina, is gradually descended in transparent quartz glass 1 provided with a heating element 5 made of carbon, is melted at the part of the exothermic body 5 and is gradually cooled at the part provided with glass fibers 4 of a heat-insulating material to turn the base metal into the alloy having a one way solidified structure in which crystals are grown downwards. By this method, the Ni based alloy having excellent ductility and strength at the ordinary temp. and high temp. of 400-800 deg.C can be obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to N1-based alloys, and is particularly applicable to main parts of gas turbines such as disks, vanes, nozzles, blades, etc., jet engines, high-temperature valves, high-temperature gas furnaces, and This invention relates to N1-based alloy structural materials that are exposed to high temperatures for long periods of time, such as in feeders.

[Conventional technology] N1 is a structural material that is exposed to high temperatures for long periods of time, such as gas turbines, jet engines, high-temperature pulp, and high-temperature gas furnaces.
Base superalloys are used.

In the case of this N1-based superalloy, the r' phase (Hl
The high temperature strength is strengthened by precipitating 1 or more f 60 vol, such as Maku, N1
The r' phase, which is the matrix phase, provides ductility and toughness.

[Problem that the invention seeks to solve]

However, for these materials, the matrix f; cNi
Since it is composed of phases, it has the disadvantage that its strength decreases significantly at high temperatures.

In contrast, the intermetallic compound Ni3A/, i! is the main reinforcing phase of the N1 superalloy. It has the unique property of increasing its strength as the humidity and temperature rise, but when used alone it lacks ductility and toughness, and when subjected to a tensile test it shows no elongation at all, making it unsuitable as a structural material. The use of materials as structural materials for high temperatures has long been a major challenge. Recently 9, this Ni1, AlK
It has been proposed that room temperature ductility can be improved by adding B13 vrt% or less (I!L?
765). However, although Ni and Al added to B1 have sufficient ductility at and near room temperature, the ductility is zero at high temperatures, particularly from 400 to 800°C, making them unsuitable as a structural material for practical use. Moreover, high temperature strength is also not sufficient.

[Object of the invention] The present invention is directed to N having high strength and high ductility at high temperatures.
i5, a new heat-resistant N1 composed of Al-based intermetallic compounds
The aim is to provide a base alloy.

[Means for solving problems]

The present invention provides: (1) Ni in atomic percentage; 75.4 to 79%; A
l; 7~129&, Hf; (L5~4%, B
; 115 or less, C; Q, 99b or less, Pe and/or CO; 45 to 11%, each 3% or less (Z) MO, W.

A heat-resistant N1-based alloy with excellent ductility at high temperatures, containing one or more elements selected from the group consisting of Wb, Ta, Zr, and V, and whose metal structure is mainly an intermetallic compound, and (2) Ni in atomic percent; 75.4-79%, Al;
7-12 children, llf; α5-4113; α5 smooth or less, C; α9% or less, We and/or Co; 45-11 yen, Mo, W, each of 5 or less.

A heat-resistant N1-based alloy containing one or more elements selected from the group consisting of Wb, Ta, Zr, and V, and whose metal structure is mainly an intermetallic compound and has a unidirectional solidification structure and has excellent ductility at high temperatures. be.

[Function] According to the present invention, by combining various additive elements to the Ni3Al alloy and further using unidirectional solidification, a material mainly composed of N1g and Al intermetallic compounds with excellent strength and ductility can be obtained. It will be done.

The reasons for limiting the composition of the alloy of the present invention will be described below. Hereinafter, the predominant component is at, 96.

Ni i Ni is one of the main elements of the alloy of the present invention, and together with A4 constitutes an L-type 2 intermetallic compound.

The basic structure of the alloy of the present invention is that M is an intermetallic compound, in which other elements other than Ni3A/, B and C serve as t-pastes, and the Alt group replaces N1 at its atomic position. It is constructed by forming a solid solution using a so-called substitution method.

This N1 is the original intermetallic compound N1. As is clear from the structural formula, the ratio of N1 to AlO is 3:1, that is, the ratio of Al is 75% in total. However, it is clear from the binary phase diagram that Ni-mu is around 75%N1 (25%ht in terms of Mut).
It has a width of about 4%.

In a multi-element N1z, Al-based intermetallic compound in which various other additive elements are added to the Ni, Al1ft base, the strength and ductility are greatly affected by the N1 content. Therefore, the amount of Ni in the alloy of the present invention is a particularly important point. If the Ni content is less than 7&4, there is no ductility at all and the material cannot be used as a structural material. In addition, the amount of Ni is 79
If it exceeds the limit, it will have ductility but will not have sufficient strength. Therefore, an amount of Ni of 7a4 to 79 is required.

kl; is an essential element to form an L-type intermetallic compound together with AlFiNi, and its necessary composition range is 7 to 12%. At less than 7%, Aj dissolves in the matrix and does not form an L1 mushroom-type intermetallic compound; at 12% or more, an L1 mushroom-type intermetallic compound is formed, but
Sufficient strength and ductility cannot be obtained due to the relationship with other additive elements.

B; B is effective in improving activity at and near room temperature. In the alloy of the present invention, B mainly precipitates at the grain boundaries and acts to strengthen the grain boundaries, and is effective when added below a59j, but II
If L exceeds 5%, it will not be effective in improving ductility and will instead become brittle.

C: Like B, C also precipitates at grain boundaries, has the function of strengthening grain boundaries, and is effective in improving ductility.

Addition of CL of 9% or less is effective, but addition of more than α9 will cause embrittlement.

Hf: HfK has two functions and is an important additive element in the alloy of the present invention. The first effect is that Hf is B,
Like C, this is an effect as a grain boundary strengthening element, and Ni5, A
It greatly contributes to improving the ductility of l-based intermetallic compounds. In particular, the effect is effective even at high temperatures, and the conventional N15, AlK
40 that could not be expected due to the addition of B and an intermetallic compound just in case
This made it possible to ensure ductility at temperatures between 0°C and 800°C.

The second effect is the effect of solid solution strengthening, in which Hf mainly
By substituting at Al sites and forming a solid solution, it works to improve the strength of the entire matrix. If the amount is less than 0.5%, there is no effect, and if the amount exceeds 4%, the solid solution strengthening effect improves the strength, but the activity decreases.

Fe and/or co; IF8 and/or co is 81 g,
It is effective in improving the ductility of Al-based intermetallic compounds.

The intermetallic compound N13 has a bonding state that is located between two types of atomic bonding modes: covalent bonding found in materials such as ceramics, and metallic bonding that is the bonding mode of metal materials. If the covalent bonding becomes strong, it becomes brittle like ceramics, and if the gold FI7A bonding becomes strong, it becomes sticky like ordinary pure gold.

Therefore, in order to improve the ductility of Ni and A4-based intermetallic compounds, it is sufficient to increase the metal bonding properties.

Transition metals such as Fe and co are effective in increasing metal bonding properties in Ni1 and Al-based intermetallic compounds. We
, Ooi, or their total width is less than 4.5, the effect is not sufficient, and even if t is added in excess of 11, the effect on improving ductility remains the same, but it reduces the high temperature strength. Put it away. Therefore, 45 to 11% is appropriate.

Mo, W, Nb, Ta, Zr, V; These elements are solid solution strengthening elements, and are mainly substituted in Al sites to form a solid solution and improve the strength of the entire matrix. Although each element has a solid solubility limit Fi of 34 or more for Ni1A4, solid solution strengthening is more pronounced when appropriate amounts of various elements are added than when a large amount of one element is added alone.

In particular, when these elements are added in a limited amount of 3% or less, solid solution strengthening is remarkable and high temperature strength is significantly improved. Therefore, each element was set to 3 or less.

〔Example〕

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

Tables 1 and 2 show the components of the alloys tested.

The test material was Inconel 75.3C (AM85
Except for 3910), those were melted in a non-consumable arc melting furnace in an argon atmosphere, and after the master alloy was prepared in the same consumable arc melting furnace, it was remelted in a one-way solidification furnace schematically shown in Figure 1. This is what I did.

FIG. 1 is a diagram schematically showing a one-way solidification furnace. In FIG. 1, 1 is transparent quartz glass, 2.3 is an alumina holder, 4 is glass fiber, 5 is a carbon heating element, 6 1 is an alumina crucible, 7 is a master alloy before melting (manufactured in an arc melting furnace), 8 is a molten sample, 9 is a sample with a unidirectionally solidified structure, and 10 is a high frequency coil.

A sample 7, which is a master alloy before melting produced in an arc melting furnace, is placed in a crucible 6, and the crucible 6 is directed downward through a furnace made of transparent quartz glass 1 (the furnace is filled with argon gas). move at a constant speed. In this case, since the heat source is limited to the carbon heating element 5, the portion that melts is limited to the sample 7, which becomes the molten sample 8. Therefore, by slowly moving the crucible 6 downward, an ingot with crystals extending downward, that is, a sample 9 having a unidirectional solidification structure is obtained.

-1~Il&116: 50 at 1050℃ after melting
After being subjected to time equalization treatment, it was subjected to a test.

On the other hand, a commercially available Inconel 75.3C with Na17 was tested. In addition, although the component amounts for F1 to -16 are shown in atomic percentages, only F17 is shown in weight percentages.

Table 5 shows the results of the tensile test conducted at 600°C. It can be seen that the strength of the material of the present invention is higher than that of the comparative material, and the elongation and reduction of area values are also high, and the material has excellent ductility. Although the material of the present invention exhibits superior material properties as an arc melting material than comparative materials,
Materials that undergo unidirectional solidification so that the direction of crystal growth matches the tensile axis of the tensile test have higher strength than arc melted materials.

FIG. 2 shows the results of a tensile test conducted at temperatures from room temperature to 1000° C. for Na11, which is an arc melting material of the present invention, and -14 and -17, which are arc melting materials of comparative examples. As is clear from this graph, it can be seen that the arc melting material of the present invention has higher strength than the comparative material.

Furthermore, Fig. 3 shows the results of tensile tests conducted at temperatures from room temperature to 1000°C for the arc-melted, unidirectionally solidified structure of the present invention -11, and the comparative materials -14 and unidirectionally solidified structures. The comparative material Na17 will be shown. As is clear from this graph, the strength of the material of the present invention is far superior to that of commercially available N1-based superalloys.

〔Effect of the invention〕

Since the material of the present invention has excellent strength and activity 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, high-temperature gas furnaces, and superchargers. It is possible to aim for

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a unidirectional solidification furnace for forming a unidirectional solidification structure, and FIGS. 2 and 3 are graphs showing the superior strength of the N1-based alloy of the present invention.

Claims (2)

[Claims] (1) Ni; 75.4-79%, Al; 7 in atomic percentage
~12%, Hf; 0.5-4%, B; 0.5% or less, C
; 0.9% or less, Fe and/or Co; 4.5 to 11%
, each containing 3% or less of one or more elements selected from the group consisting of Mo, W, Nb, Ta, Zr, and V, and is ductile at high temperatures characterized by a metal structure mainly consisting of intermetallic compounds. Excellent heat-resistant Ni-based alloy. (2) Ni: 75.4-79%, Al: 7 in atomic percentage
~12%, Hf; 0.5-4%, B; 0.5% or less, C
; 0.9% or less, Fe and/or Co; 4.5 to 11%
, each containing 3% or less of one or more elements selected from the group consisting of Mo, W, Nb, Ta, Zr, and V, and the metal structure is mainly an intermetallic compound and has a unidirectional solidification structure. A heat-resistant Ni-based alloy with excellent ductility at high temperatures.