JP3653544B2 - Ir-Nb alloy with improved creep life - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to an Ir—Nb alloy with improved creep life. More specifically, the invention of this application has a creep life that is considered to be an effective material for members used under high temperature and high stress, such as jet engines, turbine blades of gas turbines, turbine vanes, and spacecraft engines. It relates to an improved Ir-Nb alloy.
[0002]
[Prior art and its problems]
Creep characteristics are the most required characteristic of heat-resistant alloys that form members used under high temperature and high stress, such as jet engines, turbine blades of gas turbines, turbine vanes, and spacecraft engines. In particular, heat-resistant alloys used for spacecraft engines are required to have a high creep life at around 1800 ° C.
[0003]
In order to achieve such high creep characteristics, a two-phase matching structure of fcc and Ll ₂ has been formed based on a noble metal with a high melting point and excellent oxidation resistance, especially iridium, which has excellent characteristics. An iridium-based binary alloy has been developed, but even this iridium-based binary alloy often enters the accelerated creep region in several hours at temperatures above 1600 ° C and is often destroyed at 1800 ° C .
[0004]
The invention of this application has been made in view of the above circumstances, and is a member used under high temperature and high stress, such as a jet engine, a turbine blade of a gas turbine, a turbine vane, and a spacecraft engine. It is an object to provide an Ir—Nb alloy having an improved creep life, which is considered to be an effective material.
[0005]
[Means for Solving the Problems]
The inventors of the invention of this application, was intensive studies to solve the problems described above, an iridium based binary alloy mentioned above, i.e., the iridium-based, two-phase matching structure of fcc and Ll ₂ is formed Ir-Nb alloy, in which a predetermined amount of a third element called nickel or zirconium is added to an iridium-based binary alloy, is solid solution strengthened by the addition of the third element, and shows a 2% creep strain at 1600 ° C or higher. Was found to exceed 100 hours, and the invention of this application was completed.
[0006]
That is, the invention of this application is based on iridium (Ir), niobium (Nb) added to this, and a precipitate having an Ll ₂ structure in a matrix having an fcc structure, as a solution to the above-described problem. In the Ir—Nb alloy in which Ni is precipitated in conformity with the parent phase, niobium is added in an amount of 13 to 20 atomic%, and nickel (Ni) is further added in an amount of 1 atomic% to 5 atomic% in the Ir—Nb alloy. Provided is an Ir—Nb alloy having improved creep life (claim 1) characterized in that a time of showing 2% creep strain at 1600 ° C. or more shows a creep life of 100 hours or more.
[0007]
Further, the invention of this application is based on iridium (Ir), to which niobium (Nb) is added, and in which the precipitate having the Ll ₂ structure is precipitated in alignment with the parent phase in the parent phase having the fcc structure. -Nb alloy contains niobium and zirconium (Zr) in an amount of 1 atomic percent or more, and the total amount of niobium and zirconium is in the range of 10 to 20 atomic percent, with a creep rate of 2% above 1600 ° C. time indicating the distortion also provides the creep life, characterized by indicating the 100 hours of creep life improved Ir-Nb alloy (claim 2).
[0008]
Hereinafter, the Ir—Nb alloy with improved creep life of the invention of this application will be described in more detail with reference to examples.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the Ir—Nb alloy with improved creep life according to the invention of this application has a matching structure in which a precipitate having an Ll ₂ structure is precipitated in alignment with a parent phase in a parent phase having an fcc structure. It is. This matched structure is effective in ensuring a certain level of creep characteristics. That is, when stress is applied from the outside, the interface between the parent phase and the precipitate can be strained, thereby increasing the strength of the alloy, which is reflected in the creep characteristics.
[0010]
Note that even if a precipitate having an Ll ₂ structure is precipitated, if the precipitate does not match the matrix having the fcc structure, distortion is impossible and the creep characteristics are not so high.
[0011]
In the invention according to claim 1, such a two-phase matched structure of fcc and Ll ₂ is obtained when the addition amount of niobium is 13 to 20 atomic% and the addition amount of nickel is 1 atomic% or more and 5 atomic% or less. In addition, in the invention according to the second aspect, niobium and zirconium are each added in an amount of 1 atomic% or more, and when niobium and zirconium are added in a total amount in the range of 10 to 20 atomic%, they are formed satisfactorily. When the amount is less than or exceeds the above range, the consistency between the parent phase and the precipitate is disturbed, and the volume ratio of the precipitate is not appropriate, and the creep characteristics are drastically lowered. If the volume fraction of the precipitate is too small, there is not a sufficient interface. Conversely, if the volume ratio is too large, the precipitate tends to be coarsened and the area of the interface is reduced. This leads to a dramatic decrease in creep properties.
[0012]
【Example】
(Example 1)
In the phase diagram of Ir—Nb—Zr shown in FIG. 1, alloys within the hatched area (within the scope of the invention according to claim 2 of the present invention), that is, Ir-12.75Nb-3Zr, Ir-8.5- 6Zr, Ir-4.25Nb-9Zr, Ir-5Nb-5Zr and Ir-12.5Nb-12.5Zr out of the hatched area, a total of five types of alloys, the conventional Ir without the third element Zr added It was fabricated by a process similar to that used for the production of the -Nb alloy. The chart of FIG. 2 shows the X-ray diffraction results of these five types of Ir—Nb alloys.
[0013]
As can be seen from FIG. 2, the Ir—Nb alloy having a composition within the hatched range of the phase diagram shown in FIG. 1 is a two-phase alloy of fcc and Ll ₂ . FIG. 3 is a secondary electron image after heat treatment at 1500 ° C. for 72 hours for three of these two-phase alloys. From FIG. 3, fine precipitates are precipitated in alignment with the parent phase. Is confirmed.
[0014]
FIG. 4 is a graph showing the results of a creep test at 1800 ° C. of Ir-12.75Nb-3Zr of the above two-phase alloys.
[0015]
FIG. 4 also shows the result of a creep test of a conventional Ir—Nb alloy for comparison.
[0016]
As can be seen from FIG. 4, the Ir—Nb alloy of the invention of this application has a time of 2% creep strain exceeding 100 hours. There is a marked improvement in creep life.
(Example 2)
Regarding the Ir—Nb alloy of the invention according to claim 1 of the invention of this application, for comparison of the creep properties with the Ir—Nb alloy having an addition amount of Ni of 5 atomic% or less (excluding 0%), An alloy in which the addition amount of Ni exceeds 5 atomic% and a conventional Ir—Nb alloy without addition of Ni were produced by the same process as the above-described Ir—Nb alloy with addition of Zr, and each was subjected to X-ray diffraction. The results are shown in the charts of FIGS. 5a, 5b, and 5c. Both charts confirm that the Ir—Nb alloy is a two-phase alloy of fcc and Ll ₂ .
[0017]
Next, the four types of Ir—Nb alloys shown in FIGS. 5a to 5c were subjected to a creep test (stress: 137 MPa) at 1650 ° C. The graph of FIG. 6 shows the result.
[0018]
As can be seen from the graph of FIG. 6, the Ir—Nb alloy having an addition amount of Ni of 1 atomic% to 5 atomic% has a creep strain of 2% for 240 hours or more. In contrast, the conventional Ir-Nb alloy without addition of Ni and the addition amount of Ni exceed 5 atomic%, and the Ir-Nb alloy of 10 atomic% enters the accelerated creep region within 60 hours and deforms severely.
[0019]
The Ir—Nb alloy according to claim 1 of the invention of this application is an alloy with improved creep life as the name suggests, and the improvement in creep life is significantly remarkable. More revealed.
[0020]
Of course, the invention of this application is not limited by the above embodiments and examples. It goes without saying that various modes are possible for details such as the manufacturing process of the Ir-Nb alloy and various parameters in the creep test.
[0021]
【The invention's effect】
As described in detail above, the invention of this application provides an Ir—Nb alloy with improved creep life. This Ir-Nb alloy is considered to be an effective material for members that are used under high temperature and high stress, such as jet engines, turbine blades of gas turbines, turbine vanes, and spacecraft engines.
[Brief description of the drawings]
FIG. 1 is a state diagram of Ir—Nb—Zr.
2 is a chart showing X-ray diffraction results of a Zr-added Ir—Nb alloy in Example 1. FIG.
3 is a secondary electron image after performing heat treatment at 1500 ° C. for 72 hours for three types of the two-phase alloys in Example 1. FIG.
4 is a graph showing the results of a creep test of Ir-12.75Nb-3Zr in Example 1 at 1800 ° C. together with the results of a conventional Ir—Nb alloy creep test. FIG.
FIG. 5 shows a, b, and c, respectively, of the Ir—Nb alloy with the Ni addition amount of 5 atomic% or less (excluding 0%) and the Ni addition amount of 5 atomic% in Example 2. FIG. 6 is a chart showing the results of X-ray diffraction with an alloy exceeding 30 wt.
FIG. 6 is a graph showing the results of a creep test at 1650 ° C. for the four types of Ir—Nb alloys shown in FIGS. 5a to 5c.

Claims (2)

In an Ir-Nb alloy in which niobium (Nb) is added to this based on iridium (Ir) and precipitates having an Ll ₂ structure are aligned with the parent phase in the parent phase having an fcc structure, niobium is Addition of 13 to 20 atomic%, and furthermore, to this Ir-Nb alloy, nickel (Ni) is added at 1 atomic% or more and 5 atomic% or less, and the time showing 2% creep strain at 1600 ° C. or more is 100 hours or more. An Ir-Nb alloy with improved creep life, characterized by exhibiting a creep life. In an Ir-Nb alloy in which niobium (Nb) is added to this based on iridium (Ir) and precipitates having an Ll ₂ structure are precipitated in alignment with the parent phase in the parent phase having an fcc structure, Zirconium (Zr) is added in an amount of 1 atomic% or more, and the total amount of niobium and zirconium is in the range of 10 to 20 atomic%, and the time to show 2% creep strain at 1600 ° C or higher is 100 hours. An Ir—Nb alloy with improved creep life, characterized by exhibiting the above creep life.

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