CN111496417B

CN111496417B - Ti-Ni-Nb-Zr brazing material of Nb-Si-based ultrahigh-temperature structural material and brazing connection process

Info

Publication number: CN111496417B
Application number: CN202010392447.3A
Authority: CN
Inventors: 任新宇; 熊华平; 静永娟; 程耀永; 尚泳来
Original assignee: AECC Beijing Institute of Aeronautical Materials
Current assignee: AECC Beijing Institute of Aeronautical Materials
Priority date: 2020-05-11
Filing date: 2020-05-11
Publication date: 2021-12-24
Anticipated expiration: 2040-05-11
Also published as: CN111496417A

Abstract

The invention belongs to the technical field of welding, and in particular relates to a Ti-Ni-Nb-Zr brazing material of Nb-Si-based ultra-high temperature structural material and a brazing connection process. At present, there is a lack of special brazing materials for the connection of Nb-Si-based ultra-high temperature structural materials, which can reduce the content of brittle phases in the joints and obtain brazed joints with higher strength. The Ti-Ni-Nb-Zr brazing filler metal of the Nb-Si-based ultra-high temperature structural material of the present invention has chemical composition and weight percentage as follows: Ni: 15.0-20.0, Nb: 12.0-18.0, Zr: 18.0-25.0, the remainder for Ti. The brazing material has good spreading performance, can be well wetted and spread on the Nb-Si base surface, has good plasticity, can be processed into different forms of brazing material, and is beneficial to the addition and assembly of the brazing material before soldering .

Description

Ti-Ni-Nb-Zr brazing material of Nb-Si-based ultrahigh-temperature structural material and brazing connection process

Technical Field

The invention belongs to the technical field of welding, and particularly relates to a Ti-Ni-Nb-Zr brazing material of an Nb-Si-based ultrahigh-temperature structural material and a brazing connection process.

Background

Advanced aircraft engines have higher turbine temperatures, which require higher temperature capability of the blade material. At present, the temperature bearing capacity of the fifth generation nickel-based single crystal superalloy, which is the most advanced blade material, still does not exceed 1150 ℃, and reaches more than 80% of the melting point of the fifth generation nickel-based single crystal superalloy, and the fifth generation nickel-based single crystal superalloy approaches the limit use temperature of the fifth generation nickel-based single crystal superalloy, so that the use requirement of a future high-performance engine is difficult to meet.

The Nb-Si based ultra-high temperature structural material mainly consists of a solid solution of Nb (Nb)_SS) And an intermetallic compound Nb₅Si₃Two-phase composition of Nb_SSHas good room temperature toughness and intermetallic compound phase Nb₅Si₃The high-temperature-resistant material has excellent high-temperature strength, large unit cell lattice constant, difficulty in dislocation and creep, good creep resistance and thermodynamic stability at 1600-1800 ℃. The Nb-Si based ultra-high temperature structural material with a tough/brittle two-phase structure is formed by Nb_SSProviding room temperature ductility of the material, Nb₅Si₃Providing high temperature strengthThe high-temperature-resistant high-strength composite material has certain room temperature plasticity while ensuring excellent high-temperature strength, and is expected to become a next-generation advanced aeroengine blade material. Generally speaking, the service temperature can be as high as 1200-1400 ℃.

The Nb-Si based ultra-high temperature structural material has high melting point, high rigidity, low density and excellent high temperature strength, has great potential to replace the existing Ni based high temperature alloy and is applied to the aerospace field. Soldering/joining is one of the indispensable key manufacturing techniques to achieve its engineering applications. At present, few relevant documents are reported about the connection of the materials. The connection of Nb-Si-based ultrahigh-temperature structural materials can be realized by adopting traditional Ni-based brazing materials BNi-2(Ni-7Cr-5Si-3B-3Fe, mass percent), BNi-5(Ni-19Cr-10Si, mass percent) and the like, but the excessively high Ni content in the brazing materials enables a large amount of Ni-Nb and Ni-B brittle intermetallic compound phases to be generated in a joint, so that the defects of microcracks, unwelded joints and the like are generated in the joint, and the joint strength is low.

Therefore, the special brazing material for connecting Nb-Si based ultra-high temperature structural materials is lacked, the content of brittle phases in the joint can be reduced, and the brazed joint with higher strength is obtained.

Disclosure of Invention

The invention aims to specially design a Ti-Ni-Nb-Zr brazing material of an Nb-Si-based ultrahigh-temperature structural material and a brazing connection process aiming at the technical defects, so that the effective brazing connection of the Nb-Si-based ultrahigh-temperature structural material is realized, and a brazed joint with excellent room temperature and high temperature strength is obtained.

The purpose of the invention is realized by the following technical scheme:

a Ti-Ni-Nb-Zr brazing solder of an Nb-Si based ultrahigh temperature structure material comprises the following chemical components in percentage by weight: ni: 15.0-20.0, Nb: 12.0 to 18.0, Zr: 18.0 to 25.0, and the balance Ti.

Optionally, the brazing material comprises the following chemical components in percentage by weight: ni: 15.0 to 17.0, Nb: 12.0 to 18.0, Zr: 18.0 to 25.0, and the balance Ti.

Optionally, the brazing material comprises the following chemical components in percentage by weight: ni: 17.0 to 20.0, Nb: 12.0 to 18.0, Zr: 18.0 to 25.0, and the balance Ti.

Optionally, the brazing material comprises the following chemical components in percentage by weight: ni: 16.0, Nb: 12.0 to 18.0, Zr: 18.0 to 25.0, and the balance Ti.

Optionally, the brazing material comprises the following chemical components in percentage by weight: ni: 15.0-20.0, Nb: 14.0 to 18.0, Zr: 18.0 to 25.0, and the balance Ti.

Optionally, the brazing material comprises the following chemical components in percentage by weight: ni: 15.0-20.0, Nb: 12.0 to 18.0, Zr: 20.0, and the balance being Ti.

The brazing connection process of the Nb-Si based ultrahigh-temperature structural material adopts the Ti-Ni-Nb-Zr brazing material and comprises the following steps:

cleaning the surfaces of a first Nb-Si-based ultrahigh-temperature structure material and a second Nb-Si-based ultrahigh-temperature structure material to be brazed, and assembling, wherein the fit clearance of the first Nb-Si-based ultrahigh-temperature structure material and the second Nb-Si-based ultrahigh-temperature structure material is 0.02-0.09 mm;

fixing the brazing solder at the fitting angle of the first Nb-Si base ultra-high temperature structure material and the second Nb-Si base ultra-high temperature structure material to be welded or between the first Nb-Si base ultra-high temperature structure material and the second Nb-Si base ultra-high temperature structure material to be welded, and ensuring close fitting;

step three, uniformly coating aluminum oxide flow resisting agents on the top and the bottom of a welding seam, and then placing a combination of the first Nb-Si-based ultrahigh-temperature structural material and the second Nb-Si-based ultrahigh-temperature structural material to be welded and the brazing material in a vacuum heating furnace for brazing;

step four, adjusting the vacuum degree in the furnace to be better than 8 multiplied by 10^-3And when Pa is needed, heating, wherein the heating speed is not more than 15 ℃/min, the brazing connection temperature is 1250-1290 ℃, the heat preservation time is 50-100 min, and furnace cooling is carried out after the heat preservation is finished.

Optionally, the braze is in the form of a block, a strip, a wire, or an alloy powder.

Optionally, the first Nb-Si-based ultra-high temperature structural material and the second Nb-Si-based ultra-high temperature structural material are assembled and combined by adopting a butt joint or splicing method.

Alternatively, the braze joint temperature is 1270 ℃.

The technical scheme of the invention has the advantages and beneficial effects that:

1. the solder has good spreading performance, can be well wetted and spread on the surface of the Nb-Si-based alloy, has good plasticity, can be processed into different solder forms such as blocks, strips, wires or alloy powder, and is beneficial to adding and assembling the solder before welding;

2. in the invention, a certain content of Ni is added for reducing the melting point of the brazing solder, but the content of the Ni element in the brazing solder is controlled to be not more than 20 percent by mass, so that the generation tendency and the content of Ni-Nb and Ni-Ti brittle compound phases in the joint can be reduced; the other elements Nb and Ti in the brazing material are constituent elements of Nb-Si alloy base metal, and the element Zr and Nb are completely mutually soluble, so that the brazing material has good compatibility with the welded Nb-Si base metal, and the joint performance is improved;

3. the brazing filler metal disclosed by the invention is combined with related binary alloy phase diagram theoretical calculation and repeated test optimization to obtain brazing filler metal components with reasonable Ti-Ni-Nb-Zr component distribution ratio, the melting temperature range is 1194-1223 ℃, the connection can be carried out within the brazing temperature range of 1230-1300 ℃, the recommended brazing connection temperature is 1250-1290 ℃, the heat treatment temperature is lower than that of Nb-Si base metal (1450-1500 ℃), and the performance of the base metal is not damaged; moreover, under the condition that the brazing connection temperature is 1250-1290 ℃, and the fit clearance of the materials to be welded is 0.02-0.09 mm, the welding seam can be welded at one time without repair welding, and the defects of corrosion, fusion, microcrack and the like in the brazing seam can be ensured;

4. the brazing filler metal and the joint obtained under the process condition have high performance, the joint structure obtained by interdiffusion of the brazing filler metal and the base metal is close to the base metal, and the joint mainly comprises (Nb, Ti) solid solution phase and Nb₅Si₃Phase composition, and Ti, Zr and Ni elements in the brazing filler metal are dissolved in (Nb, Ti)_SSAnd (Nb, Ti, Zr)₅Si₃In the phase, the connecting joint does not have residual brazing filler metal with the melting temperature of 1194-1223 ℃ or brittle intermetallic compound phases such as Ni-Nb, Ni-Ti and the like. When the Ni-based brazing filler metal is adopted, a large amount of brittle intermetallic compound phases such as Nb-Ni, Ni-Si, Ni-B and the like are generated in a joint due to high elements such as Si, B and the like, so that the joint strength is low, and even microcracks occur in the joint. The room temperature bending strength of the connecting joint obtained by the brazing material reaches330-363 MPa, which is 60-66% of the room-temperature bending strength (550MPa) of the base material, and is 40-45% higher than the Ni-based brazing filler metal joint. Due to the main phase (Nb, Ti) in the soldered joint_SSAnd (Nb, Ti, Zr)₅Si₃The melting temperature of the phase is up to more than 2000 ℃, so that the connecting joint has satisfactory high-temperature strength, the high-temperature bending strength of the joint reaches 152-168 MPa at 1200 ℃, 54-60% of the high-temperature bending strength (280MPa) of the base material is reached, and the performance of the connecting joint exceeds that of other conventional brazing materials;

5. the brazing material is green and environment-friendly, does not contain toxic elements, and does not contain noble metal elements such as Ag, Au, Pd, Pt and the like.

Drawings

FIG. 1 is a schematic view of a weld configuration of an embodiment of a butt joint;

fig. 2 is a schematic view of a welding structure of an embodiment of the plug connector.

In the figure: 1 is a first Nb-Si based ultra-high temperature structural material to be brazed, 2 is a second Nb-Si based ultra-high temperature structural material to be brazed, and 3 is brazing solder.

Detailed Description

The technical scheme of the invention is further detailed in the following by combining the drawings and the embodiment:

referring to fig. 1 for the butt-joint brazing position and fig. 2 for the splicing brazing position, the brazing material 3 is fixed at the fitting angle of the first and second Nb-Si based ultra-high temperature

structural materials

1 and 2 to be welded or is arranged between the two materials, and close fitting is ensured.

Table 1 shows the components and weight percentage compositions of the Ti-Ni-Nb-Zr brazing material for the Nb-Si based ultra high temperature structural material according to the technical solution of the present invention, and lists examples of 16 Ti-Ni-Nb-Zr brazing materials.

TABLE 1 compositions and weight percentages of brazing materials in examples of the invention

The following 11 components (all atomic ratios) Nb-Si based ultra-high temperature structural materials are brazed and connected by adopting the brazing materials with the compositions of examples 1 to 16 shown in Table 1 and respectively used as blocks, strips, wires or alloy powder at the brazing temperature of 1250-1290 ℃ for the heat preservation time of 50-100 min:

(1)Nb-17Si-23Ti；

(2)Nb-18Si-24Ti-2Cr-2Al-2Hf；

(3)Nb-16Si-22Ti-3Cr-2Al-2Hf；

(4)NB-17Si-20Ti-8Zr-2Al-2Hf；

(5)Nb-18Si-20Ti-12Zr-3Mo-2Al；

(6)Nb-26Si-22Ti-6Cr-3Al-2Hf；

(7)Nb-16Si-22Ti-3Cr-3Al-2Hf；

(8)Nb-12Si-24Ti-4Cr-4Al-2Hf；

(9)Nb-20Si-24Ti-2Cr-2Al；

(10)Nb-16Si-10Ti-10Zr-3Cr-3Al-2Hf；

(11)Nb-16Si-20Ti-4V-3Cr-3Al-2Hf。

verification of connection effect of each embodiment: the joint structure obtained by interdiffusion of the brazing filler metal and the base metal is close to the base metal and mainly comprises (Nb, Ti) solid solution phase and Nb₅Si₃Phase composition, and Ti, Zr and Ni elements in the brazing filler metal are dissolved in (Nb, Ti)_SSAnd (Nb, Ti, Zr)₅Si₃In the phase, the connecting joint does not have residual brazing filler metal with the melting temperature of 1194-1223 ℃ or brittle intermetallic compound phases such as Ni-Nb, Ni-Ti and the like. The room-temperature bending strength of the connection joint obtained by the brazing material reaches 330-363 MPa, reaches 60-66% of the room-temperature bending strength (550MPa) of a base material, and is 40-45% higher than that of a Ni-based brazing filler metal joint. Due to the main phase (Nb, Ti) in the soldered joint_SSAnd (Nb, Ti, Zr)₅Si₃The melting temperature of the phase is up to 2000 ℃ or above, so that the connection joint has satisfactory high-temperature strength, the high-temperature bending strength of the joint reaches 152-168 MPa at 1200 ℃, and the high-temperature bending strength of the base material reaches 54-E (600 MPa)60%, the performance of the connection joint exceeds that of other existing conventional brazing materials.

It should be noted that, in the embodiments described in the present invention, the formula of the brazing material, the name of the process, the name and specific components of the material to be brazed, etc. may be different. All equivalent or simple changes of the structure, the characteristics and the principle based on the patent conception of the invention are included in the protection scope of the invention.

Claims

1. a Ti-Ni-Nb-Zr brazing filler metal of Nb-Si-based ultra-high temperature structural material, is characterized in that: the chemical composition and weight percent of this brazing filler metal are: Ni: 15.0～20.0, Nb: 12.0～ 18.0, Zr: 18.0 to 25.0, and the balance is Ti.

2. The Ti-Ni-Nb-Zr brazing filler metal according to claim 1, wherein the chemical composition and weight percentage of the brazing filler metal are: Ni: 15.0-17.0, Nb: 12.0-18.0, Zr: 18.0 to 25.0, and the balance is Ti.

3. The Ti-Ni-Nb-Zr brazing filler metal according to claim 1, wherein the chemical composition and weight percentage of the brazing filler metal are: Ni: 17.0-20.0, Nb: 12.0-18.0, Zr: 18.0 to 25.0, and the balance is Ti.

4. The Ti-Ni-Nb-Zr brazing material according to claim 1, wherein the chemical composition and weight percentage of the brazing material are: Ni: 16.0, Nb: 12.0-18.0, Zr: 18.0- 25.0, the balance is Ti.

5. The Ti-Ni-Nb-Zr brazing filler metal according to claim 1, wherein the chemical composition and weight percentage of the brazing filler metal are: Ni: 15.0-20.0, Nb: 14.0-18.0, Zr: 18.0 to 25.0, and the balance is Ti.

6. The Ti-Ni-Nb-Zr brazing filler metal according to claim 1, wherein the chemical composition and weight percentage of the brazing filler metal are: Ni: 15.0-20.0, Nb: 12.0-18.0, Zr: 20.0, and the balance is Ti.

7. A brazing connection process of Nb-Si-based ultra-high temperature structural material, characterized in that: using the Ti-Ni-Nb-Zr brazing filler metal as described in any one of claims 1-6, and comprising: The following steps:

Step 1: Clean the surfaces of the first and second Nb-Si-based ultra-high temperature structural materials (1, 2) to be brazed, and assemble them, with a matching gap of 0.02-0.09 mm;

Step 2, fixing the brazing material (3) at the matching corners of the first and second Nb-Si-based ultra-high temperature structural materials (1, 2) to be welded or between the two to ensure a tight fit;

Step 3: Coat the top and bottom of the weld evenly with alumina flow blocking agent, and then place the first and second Nb-Si-based ultra-high temperature structural materials (1, 2) and the brazing filler metal (3) to be welded. The assembly is placed in a vacuum heating furnace to prepare for brazing;

Step 4: When the vacuum degree in the furnace is adjusted to be better than 8×10 ^-3 Pa, the temperature rises, the heating rate is not more than 15°C/min, the temperature of the brazing connection is 1250～1290°C, and the holding time is 50～100min. Cool in the oven.

8. The brazing connection process of Nb-Si-based ultra-high temperature structural material according to claim 7, wherein the brazing material (3) is in the form of block, strip, wire or alloy powder.

9. The brazing connection process of the Nb-Si-based ultra-high temperature structural material according to claim 7, wherein , 2) Assemble and combine.

10 . The brazing connection process of the Nb-Si-based ultra-high temperature structural material according to claim 7 , wherein the brazing connection temperature is 1270° C. 11 .