CN114032412B

CN114032412B - 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy

Info

Publication number: CN114032412B
Application number: CN202111314314.5A
Authority: CN
Inventors: 种晓宇; 余威; 冯晶; 干梦迪; 张健康; 魏燕; 胡昌义; 张爱敏
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2021-11-08
Filing date: 2021-11-08
Publication date: 2022-07-01
Anticipated expiration: 2041-11-08
Also published as: CN114032412A

Abstract

The invention discloses a 1400 ℃ resistant high-strength creep-resistant Pt-based high-temperature alloy, which relates to the technical field of high-temperature alloys, and the technical scheme is as follows: the alloy consists of elements Pt, Zr, Hf, Ni, Cr and X, wherein X is one or more of Sc, Ti, Co, Y, Ce and Th. The elements are calculated by mass percent: 9-15% of Zr, 5-14% of Hf, 6-12% of Sc, 0-10% of Ti, 3-8% of Ni, 2-7% of Co, 7-11% of Cr, 0-1% of Y, 0-1% of Ce, 0-1% of Th and the balance of Pt. The method has the effects of improving the high-temperature strength and creep resistance of the gamma/gamma' type Pt-based high-temperature alloy of a Pt-Al system and reducing the use cost of the platinum-based alloy.

Description

1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy

Technical Field

The invention relates to the technical field of high-temperature alloys, in particular to a 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy.

Background

The production of the high-temperature alloy is mainly to meet the harsh requirements of the jet engine on materials, the high-temperature alloy in the traditional sense refers to nickel-based, iron-based, cobalt-based, titanium-based and intermetallic compounds thereof and other base metals, the high-temperature alloy is mainly applied to hot end parts of aero-engines, industrial gas turbines and the like, the nickel-based superalloy serving as one of high-temperature structural materials is a main material of the current hot end parts of aerospace, gas turbines and the like, however, due to the limitation of melting point, the service temperature of the nickel-based alloy is close to the limit, and the nickel-based alloy is difficult to be further improved.

The noble metal platinum (Pt) has not only the same crystal structure (face-centered cubic structure) as Ni but also the melting point (1) of Pt768 ℃) is far higher than the melting point (1455 ℃) of Ni, has excellent oxidation resistance and corrosion resistance, generally does not need coating protection when being used at high temperature, can withstand the test of high temperature and severe complex environment, and becomes an indispensable material in a plurality of special application environments. However, pure platinum has a serious growth of crystal grains at high temperature, the high-temperature strength and creep resistance are reduced, the pure platinum cannot be used for a long time under the condition of high-temperature stress, and the high-temperature strength of the Pt-based alloy is usually improved by adopting a solid solution strengthening or dispersion strengthening mode. For the Pt-Ir alloy, Ir can volatilize at high temperature to reduce the high-temperature stability of the material, the volatilization of a large amount of Ir can greatly damage the performance of the material, and meanwhile, the ductility of Ir is poor, so that the Pt-Ir alloy is difficult to process. For the Pt-Rh alloy, the solid solution strengthening effect of Rh element is weaker at room temperature, and the price of Rh element is high, so that the cost of the whole Pt-Rh alloy is increased. Usually, a small amount of (C) is added to the Pt-Rh alloy<1%) of Mo, W, Ru, Ir, and the like, improves the endurance strength of the alloy, reduces creep speed, but at high temperature, these elements are easily oxidized and volatilized, and the volatilization loss of these elements rapidly increases with the increase of temperature, so that the high-temperature strength of the material is reduced. In addition, the solid solution strengthened alloy has coarsening of crystal grains at high temperature, which greatly damages the mechanical property of the material. For dispersion strengthened Pt-based alloys, it is common to add carbides (TiC) or oxides (ZrO) to the Pt-based alloy₂、Y₂O₃) The mechanical property of the material is improved, but the dispersion strengthening Pt-based alloy has poor processing property, and the plasticity of the material is usually greatly reduced.

The gamma/gamma' type Ni-based high-temperature alloy has excellent mechanical property at high temperature, and Pt has the same crystal structure as Ni, which provides reference significance for developing Pt-based high-temperature alloys with similar structures. At present, the research on gamma/gamma' type Pt-based high-temperature alloy is mainly focused on a Pt-Al system, because Pt₃The melting point of Al is only 1556 ℃, and Pt is₃Al and Pt are subjected to eutectic reaction at 1505 ℃, so that the service temperature of the gamma/gamma' -type Pt-based high-temperature alloy of a Pt-Al system is difficult to break 1300 ℃.

Disclosure of Invention

The invention aims to provide a 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy, and solves the problem that when a gamma/gamma 'type Pt-based high-temperature alloy of a Pt-Al system is applied in a 1300 ℃ environment, the high-temperature strength and creep resistance of the gamma/gamma' type Pt-based high-temperature alloy are poor.

In order to achieve the purpose, the invention adopts the following technical scheme:

the 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy consists of elements Pt, Zr, Hf, Ni, Cr and X, wherein X is one or more of Sc, Ti, Co, Y, Ce and Th.

The four alloy elements of Sc, Ti, Zr and Hf are gamma 'phase elements and are mainly used for forming a gamma' phase with a high melting point in the Pt-based alloy. The formation of the two-phase coherent structure of the gamma/gamma ' phase not only adds the gamma ' phase alloy element, but also adds the alloy element to lead the alloy element to be dissolved into the Pt matrix, regulates and controls the lattice constant of the gamma/gamma ' phase, and leads the interface energy and the distortion to reach the proper proportion. The Ni and the Co are mainly added, so that the method is used for regulating and controlling the degree of mismatching of two phases of a gamma/gamma 'phase in the Pt-based high-temperature alloy to ensure the formation of the gamma' phase with a cubic morphology on the one hand, and is used for reducing the stacking fault energy of the alloy, inhibiting the precipitation of harmful phases and improving the creep resistance of the alloy on the other hand.

In addition, the four gamma 'phases are greatly different, and two common gamma' phases (Pt) are selected firstly in the invention₃Zr and Pt₃Hf), to which Ti and Sc are added, respectively, to control the kind of the γ' phase. Meanwhile, the volume fraction of the gamma' phase also has important influence on the high-temperature strength and the creep resistance of the alloy. Therefore, the invention mainly adds alloy elements to Pt to promote the formation of high-melting-point gamma' phase in Pt-based alloy, such as Pt₃Sc(1850℃)、Pt₃Ti(>1900℃)、Pt₃Zr (2154 ℃ C.) and Pt₃Hf (2000 ℃ C.). The service temperature, the high-temperature strength and the creep resistance of the alloy are improved, and the cost of the Pt-based high-temperature alloy is reduced.

Further, the alloy comprises the following elements in percentage by mass: 9-15% of Zr, 5-14% of Hf, 6-12% of Sc, 0-10% of Ti, 3-8% of Ni, 2-7% of Co, 7-11% of Cr, 0-1% of Y, 0-1% of Ce, 0-1% of Th and the balance of Pt. The alloy has a gamma/gamma' two-phase coherent structure, so that the high-temperature strength and the creep resistance of the alloy are greatly improved. Zr and Hf are used as gamma' phase elements with the highest melting point in the Pt-based alloy to ensure the use temperature of the alloy, and a large amount of Cr elements are added to ensure the corrosion resistance of the alloy. Sc and Ti are also gamma 'phases in the Pt-based high-temperature alloy, so that the volume fraction of the gamma' phases in the alloy is improved, the high-temperature strength of the alloy is improved, the use amount of Pt is reduced, and the alloy cost is reduced. Co element is mainly used for reducing the stacking fault energy and improving the creep resistance of the alloy. The addition of the rare earth element (Y) can refine the structure and improve the strength of the alloy. In addition, the alloy does not contain expensive alloy elements such as Re, Rh and the like, and the specific gravity of the alloy elements is increased to the maximum limit while the excellent high-temperature strength and creep resistance are maintained, so that the cost of the alloy is greatly reduced.

Furthermore, in the elements of the alloy, the total mass fraction of Zr, Hf, Ni, Cr and the element X is 40-60%. On one hand, the content of the gamma' phase in the Pt-based high-temperature alloy is increased to the maximum extent, and on the other hand, the use amount of the noble metal Pt is reduced to the maximum extent, so that the alloy cost is reduced.

Furthermore, in the elements of the alloy, the total volume fraction of Zr, Hf, Sc and Ti is 20-40%. The addition of a large amount of gamma 'phase alloy elements ensures the content of the gamma' phase in the Pt-based high-temperature alloy and ensures the high-temperature strength.

The preparation method of the 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy is characterized by comprising the following steps of:

step one, batching: weighing raw material powder according to the weight proportion of alloy elements, and mixing for later use;

step two, tabletting: pressing the prepared alloy powder into a sheet by using a die; the prepared alloy powder is pressed into a sheet shape, so that the impact of electric arc on the powder is reduced.

Step three, cleaning the furnace chamber: putting the pressed alloy sheet into a water-cooled copper crucible in a furnace cavity of an electric arc furnace for later use, vacuumizing the furnace and introducing argon to obtain a clean furnace cavity; is convenient for subsequent smelting.

Step four, smelting: smelting the alloy sheet in the water-cooled copper crucible, repeatedly smelting a sample for more than 3 times, and stirring simultaneously to obtain a sample with uniform components; smelting for 3 times and stirring are beneficial to ensuring the component uniformity of the alloy sample.

Step five, suction casting: and after the last smelting is finished, carrying out suction casting on the sample, and quickly sucking the molten sample into a water-cooling copper mold by virtue of the pressure difference between the cavity and the suction casting chamber to obtain a rod-shaped sample.

Further, in the second step, the pressing of the alloy powder into tablets comprises: and (3) adopting a die with the diameter of 10mm, setting the pressure to be 6MPa, and maintaining the pressure for 2 minutes. Pressing the alloy powder into tablets can reduce the impact of the arc on the powder.

Further, in the third step, the step of vacuumizing the furnace and introducing argon comprises the following specific steps: the furnace is vacuumized to 5 x 10 < -4 > pa, and argon is introduced until the pressure in the furnace is 0.5 MPa. The furnace chamber can be cleaned by vacuumizing and introducing argon gas in the furnace.

Further, in the third step, the step of vacuumizing the furnace and introducing argon is circulated for 3 times. Further cleaning the cranial cavity.

Further, in the fourth step, the sample is kept in the molten state for 60 seconds or more for each melting. Further ensuring the composition uniformity of the alloy sample.

Drawings

FIG. 1 is a graph showing the results of a high temperature tensile test at 1000 ℃ in examples 1 to 9 of the present invention and comparative examples 1 to 5;

FIG. 2 is a graph showing the results of the high temperature tensile test at 1400 ℃ for inventive examples 1 to 9 and comparative examples 1, 4 and 5;

FIG. 3 is a graph showing the results of high temperature creep tests at 1000 ℃ for examples 1 to 9 of the present invention and comparative examples 1 to 5;

FIG. 4 is a graph showing the results of the high temperature creep test at 1400 ℃ for inventive examples 1 to 9 and comparative examples 1, 4 and 5.

Detailed Description

In the scheme, Pt is a basic element, Zr, Hf, Sc and Ti are gamma' phase elements, Ni and Co are gamma phase elements, Cr is other elements, and Y, Ce and Th are rare earth elements.

The purity of the element Pt is 99.9 percent, the Pt is powdery, and the grain size is less than or equal to 1 mu m;

the purity of the element Zr is 99.5 percent, the Zr is powdery, and the grain diameter is larger than 200 meshes;

the purity of the element Hf is 99.9%, the Hf is granular, and the grain size is 1-10 mm;

the purity of the element Sc is 99.9 percent, the Sc is granular, and the grain diameter is 1-10 mm;

the purity of the element Ti is 99.95 percent, the Ti is granular, and the grain diameter is 1-10 mm;

the purity of the element Ni is 99.5 percent, the Ni is powdery, and the grain diameter is 1-10 mm;

the purity of the element Co is 99.5 percent, the Co is flaky and the thickness is 0.1 mm;

the purity of the element Cr is 99.95 percent, the Cr is powdery, and the grain diameter of the Cr is less than or equal to 10 mu m;

the purity of the rare earth element is 99.95%, the rare earth is powder, and the particle size is 300 meshes.

Example 1

The high-strength creep-resistant Pt-based high-temperature alloy with the temperature of 1400 ℃ comprises the following elements in percentage by mass: 14% Zr, 13% Hf, 7% Ni, 10% Cr, 2.3% Co, and the balance Pt. Wherein the total volume fraction of the elements Zr and Hf is 27%.

The preparation method of the 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy comprises the following steps:

step one, batching: weighing the raw materials according to the weight percentage of the alloy in the scheme, and mixing for later use.

Step two, tabletting: and (3) pressing the prepared alloy powder into a sheet by adopting a die with the diameter of 10mm and the pressure of 6MPa for 2 minutes based on the prepared alloy powder in the step one, so that the impact of the electric arc on the powder is reduced.

Step three, cleaning the furnace chamber: placing the alloy sheet into a water-cooled copper crucible in a furnace cavity of a vacuum-argon arc furnace, starting a vacuumizing device, and vacuumizing the device to 5 multiplied by 10^-4pa, introducing a certain amount of argon until the pressure of the equipment is 0.5MPa, and then vacuumizing the equipment to 5 multiplied by 10^-4pa, introducing a certain amount of argon to the pressure of the equipment to be 0.5MPa, and circulating for 3 times to obtain a clean furnace chamber. Finally, vacuumizing to 5X 10^-4When pa, a certain amount of argon is introduced until the pressure of the equipment is 0.5MPa, so that the subsequent smelting is facilitated.

Step four, smelting: and (2) smelting the alloy sheet in the step two by adopting a vacuum-argon arc smelting method, setting the smelting current to be 90-100A, repeatedly smelting one sample for more than 3 times to ensure the component uniformity of the alloy sample, keeping the sample in a molten state for more than 60 seconds during each smelting, and stirring by using a magnetic stirrer to obtain the sample with uniform components.

Step five, suction casting: and (3) after the last melting is finished, carrying out suction casting on the sample, and quickly sucking the molten sample into a water-cooling copper mold by virtue of the pressure difference between the cavity and the suction casting chamber to obtain a rod-shaped sample.

Examples 2-9 are substantially the same as example 1 except that the types and amounts of the alloying elements are selected and the differences are as detailed in Table 1.

TABLE 1

Comparative example 1

Comparative example 1 is a Pt-based superalloy (Pt-10Rh) that is currently in common use, including the following elements, in mass percent: 10% Rh, the balance being Pt.

Comparative example 2

Comparative example 2 is a Co-based superalloy (K640S) currently in common use, comprising the following elements in mass percent: 10.5% Ni, 0.55% Mn, 25.96% Cr, 7.7% W, 0.58% Si, and the balance Co.

Comparative example 3

Comparative example 3 is a currently commonly used Ni-based superalloy (DD5) comprising the following elements, in mass percent: 7.5% Co, 7% Cr, 5% W, 6.2% Al, 6.5% Ta, 1.5% Mo, 3% Re, 0.15% Hf, the balance Ni.

Comparative example 4

Comparative example 4 is a superalloy of the present invention without the addition of a gamma phase alloying element, comprising the following elements, in mass percent: 14.0% Zr, 13.0% Hf, the remainder being Pt.

Comparative example 5

Comparative example 5 is a gamma prime alloy element reduced superalloy of the present invention, comprising the following elements, in mass percent: 5% of Zr, 4% of Hf, 3% of Sc, 1% of Ti, 2.3% of Ni, 1% of Co, 7% of Cr, 0.2% of Y, 0.35% of Ce, 0.6Th and the balance of Pt.

The selection of alloying elements and the raw material cost for comparative examples 1 to 5 are shown in Table 2.

TABLE 2

High temperature tensile test

The samples of examples 1 to 9 and comparative examples 1 to 5 were subjected to a high-temperature tensile test at 1000 ℃ and a tensile rate of 0.4mm/min using an LFK-300KN electronic universal tester. In addition, since comparative examples 2 and 3 are a Co-based superalloy and a Ni-based superalloy, respectively, which have a use temperature of less than 1400 ℃, high temperature tests of 1400 ℃ were performed only for examples 1 to 9 and comparative examples 1, 4 and 5, and the test conditions were the same except for the temperature. The high temperature tensile results at a test temperature of 1000 ℃ are shown in FIG. 1, and the high temperature tensile results at a test temperature of 1400 ℃ are shown in FIG. 2.

And (4) conclusion: as can be seen from FIGS. 1 and 2, the tensile strength of each of examples 1-9 is higher than that of comparative example 3 at 1000 ℃; the tensile strengths of examples 1 and 5 are equivalent to those of comparative example 5, and it can be seen from tables 1 and 2 that the cost of comparative example 5 is higher than that of comparative example 5 in comparison with examples 1 and 5 having equivalent tensile strengths; the tensile strength of comparative examples 1-2 and comparative example 4 is significantly lower than that of examples 1-9, and in combination with tables 1 and 2, the cost of comparative example 1 is much higher than that of examples, the cost of comparative example 2 is lower than that of examples, but the tensile strength of comparative example 2 is much lower than that of examples, comparative example 4 is higher than that of examples, and the tensile strength of comparative example 4 is much lower than that of examples. Examples 1-9 have significantly higher tensile strength at 1400 ℃ than comparative examples 1, 4 and 5; and example 9 has the highest tensile strength and is much higher than the comparative example.

From the above, the tensile strength of the alloy prepared by the invention is stronger than that of the existing common Pt-based superalloy (Pt-10Rh), Co-based superalloy (K640S) and Ni-based superalloy (DD5), and the difference is more obvious when the temperature is higher. It is understood from comparative examples 1, 2 and 3 that the higher the content of the γ -type element or γ' -type element is added within a certain range, the stronger the tensile strength of the alloy. As is clear from comparative examples 4 and 5, the higher the volume fraction of the γ' -phase element in the alloy is, the stronger the tensile strength of the alloy is within a certain range.

Second, high temperature creep test

Test high temperature creep tests were conducted on the samples of examples 1 to 9 and comparative examples 1 to 5 using an RDL50 electronic high temperature creep test machine, and in addition, since comparative example 2 and comparative example 3 are a Co-based superalloy and a Ni-based superalloy, respectively, and the service temperature thereof was less than 1400 ℃, the high temperature creep test of 1400 ℃ was conducted only on examples 1 to 9 and comparative examples 1, 4 and 5, and the test conditions were the same except for the temperature. Before the test, the surface of the sample was polished with 2000 mesh sandpaper, the load was kept constant during the test, the temperature error was ± 3 ℃, the test temperatures were 1000 ℃ and 1400 ℃, the stress level was 5MPa, the results at the test temperature of 1000 ℃ are shown in fig. 3, and the results at the test temperature of 1400 ℃ are shown in fig. 4.

And (4) conclusion: as can be seen from FIGS. 3 and 4, comparative examples 1 and 5 have creep rates slightly higher than those of examples 1 to 9, and comparative examples 2, 3 and 4 have creep rates slightly higher than those of examples 1 to 9 at 1000 ℃; the creep rates of examples 1-9 were significantly lower than comparative examples 1, 4 and 5 at 1400 ℃.

As can be seen from the above, the present invention has a lower creep speed at 1400 ℃ than the conventional Pt-based superalloy (Pt-10Rh), Co-based superalloy (K640S) and Ni-based superalloy (DD 5). It is understood from examples 1 to 9 and comparative example 5 that the higher the volume fraction of the γ' -phase element added, the lower the creep rate of the alloy.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. The 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy is characterized by consisting of elements Pt, Zr, Hf, Ni, Cr and X, wherein X is one or more of Sc, Ti, Co, Y, Ce and Th; the alloy comprises the following elements in percentage by mass: 9-15% of Zr, 5-14% of Hf, 6-12% of Sc, 0-10% of Ti, 3-8% of Ni, 2-7% of Co, 7-11% of Cr, 0-1% of Y, 0-1% of Ce, 0-1% of Th and the balance of Pt.

2. The 1400 ℃ high strength creep resistant Pt-based superalloy according to claim 1, wherein the total mass fraction of Zr, Hf, Ni, Cr, and element X in the elements of the alloy is 40-60%.

3. The 1400 ℃ high-strength creep-resistant Pt-based superalloy as in claim 1, wherein the total volume fraction of Zr, Hf, Sc, and Ti in the elements of the alloy is 20-40%.

4. The method for preparing the 1400 ℃ high-strength creep-resistant Pt-based superalloy according to any of claims 1-3, comprising the steps of:

step two, tabletting: pressing the prepared alloy powder into a sheet by using a die;

step three, cleaning the furnace chamber: putting the pressed alloy sheet into a water-cooled copper crucible in a furnace cavity of an electric arc furnace for later use, vacuumizing the furnace and introducing argon to obtain a clean furnace cavity;

step four, smelting: smelting the alloy sheet in the water-cooled copper crucible, repeatedly smelting a sample for more than 3 times, and stirring simultaneously to obtain a sample with uniform components;

step five, suction casting: and after the last smelting is finished, suction casting is carried out on the sample, and the molten sample is quickly sucked into the water-cooling copper mould by virtue of the pressure difference between the cavity and the suction casting chamber to obtain a rod-shaped sample.

5. The method for preparing the 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy as claimed in claim 4, wherein in the second step, the alloy powder is pressed into tablets, specifically: and (3) adopting a die with the diameter of 10mm, setting the pressure to be 6MPa, and maintaining the pressure for 2 minutes.

6. The method for preparing the 1400 ℃ high-strength creep-resistant Pt-based high-temperature alloy as claimed in claim 4, wherein in the third step, the furnace is vacuumized and argon is introduced, specifically: the furnace is vacuumized to 5 x 10^-4pa, introducing argon gas until the pressure in the furnace is 0.5 MPa.

7. The method for preparing the 1400 ℃ high-strength creep-resistant Pt-based superalloy according to claim 4, wherein in the third step, the steps of vacuumizing the furnace and introducing argon are circulated for 3 times.

8. The method for preparing the 1400 ℃ high-strength creep-resistant Pt-based superalloy according to claim 4, wherein in the fourth step, the sample is required to be kept in a molten state for more than 60s each time of smelting.