L12 type co-ni-al-ti intermetallic compound and method for producing the same

Abstract

The application belongs to the field of intermetallic compounds and provides a L12 type Co-Ni-Al-Ti intermetallic compound and a preparation method thereof.The chemical composition of the intermetallic compound is as follows: Ni: 30%-40%, Al: 8%-14%, Cr: 0-8%, Ti: 5%-10%, Ta: 0-5%, Nb: 0-5%, Co: 18%-57%, and the matrix of the intermetallic compound is L12 phase.The L12 type Co-Ni-Al-Ti intermetallic compound and the preparation method thereof have the following advantages: the intermetallic compound is a Co-rich chemical complex intermetallic compound, is significantly better than a traditional binary Co3Ti intermetallic compound, has very excellent strength (yield strength reaches 0.89 Gpa, and tensile strength reaches 1.5 Gpa) and plasticity (reaches 30%), and because the melting point of pure Co is 50-150 DEG C higher than that of pure Ni, the melting point of the intermetallic compound is higher than the dissolution temperature (about 1100 DEG C) of a traditional nickel-based high-temperature alloy gamma' phase, and the intermetallic compound can be applied at a higher temperature.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of intermetallic compounds, and particularly relates to a L12 type Co-Ni-Al-Ti intermetallic compound and a preparation method thereof. BACKGROUND

[0002] High-temperature alloy is the core material of hot-end components in high-end industries such as aerospace, ships, gas turbines and nuclear power plants. It can be said that the performance of high-temperature alloy determines the development level of these industries. Compared with traditional nickel-based high-temperature alloy, intermetallic compounds with ordered L12 structure have high melting point, good corrosion resistance, oxidation resistance and other excellent properties, especially their excellent thermal stability and abnormal yield characteristics (increasing yield strength with temperature rise) at high temperature, which makes them have the potential to become a new generation of high-temperature structural materials.

[0003] However, traditional L12 type intermetallic compounds are usually binary and ternary alloy, such as Co3Ti and Ni3Al, which usually have poor plasticity at room temperature, which greatly limits their actual application. Therefore, how to design and prepare an intermetallic compound with high strength and toughness is one of the important topics to be solved in this field. The temperature resistance of Ni-rich alloy is often limited by the melting point of Ni element. Co element has a higher melting point (about 50-150℃ higher) than Ni element, so it is of great scientific and engineering significance to invent a L12 type Co-rich chemical complex intermetallic compound. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art, and provides a L12 type Co-Ni-Al-Ti intermetallic compound and a preparation method thereof, which has good material performance.

[0005] The technical solution of the present application is: a L12 type Co-Ni-Al-Ti intermetallic compound, the chemical composition of the intermetallic compound is as follows in atomic percentage:

[0006] Ni: 30%-40%, Al: 8%-14%, Cr: 0-8%, Ti: 5%-10%, Ta: 0-5%, Nb: 0-5%, Co: 18%-57%.

[0007] Specifically, the matrix of the intermetallic compound is L12 phase.

[0008] Specifically, the intermetallic compound has at least two of Cr, Ta and Nb.

[0009] The application also provides a preparation method of the L12 type Co-Ni-Al-Ti intermetallic compound.

[0010] The smelting step: the elements are weighed according to the element ratio of the chemical composition of the intermetallic compound and mixed and smelted to obtain an alloy.

[0011] The cooling step: the alloy is cooled to obtain a cast alloy.

[0012] The homogenization treatment step: the cast alloy is subjected to homogenization treatment to obtain a homogenized alloy part.

[0013] The cyclic rolling deformation and aging treatment step: the alloy part is subjected to cold rolling deformation, then wrapped in iron and placed in a holding furnace for annealing for a set time, and the rolling deformation and annealing are repeated.

[0014] Specifically, in the smelting step, each element is mixed and smelted in a vacuum arc smelting furnace, and inert protective gas is introduced during smelting. After the alloy is completely melted and solidified into a button ingot, it is turned over and then subjected to arc vacuum arc smelting. The step of arc vacuum arc smelting after turning over is repeated at least 8 times.

[0015] Specifically, the cooling step includes pouring the alloy into a copper mold with a liquid cooling system to obtain a lath-shaped cast alloy.

[0016] Specifically, in the homogenization treatment step, the cast alloy is wrapped in iron and subjected to homogenization treatment at 1100-1200°C in an inert gas protective atmosphere for 12 hours, and then the cast alloy is taken out and air-cooled.

[0017] Specifically, the alloy part after the homogenization treatment step is subjected to cold rolling deformation, and the rolling reduction is 20-30%. Then the cold-rolled alloy part is wrapped in iron and placed in a muffle furnace with a temperature of 1100-1200°C and inert gas protection for 15 minutes for annealing. The cyclic rolling and annealing treatment is repeated until the total rolling reduction approaches 66%. The alloy part is heat treated at a temperature of 1100-1200°C for 10-30 minutes.

[0018] Specifically, the homogenization treatment temperature of the cast alloy is 1150°C.

[0019] Specifically, the alloy part is heat treated at a temperature of 1150°C for 15 minutes.

[0020] The application provides a L12 type Co-Ni-Al-Ti intermetallic compound and a preparation method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0022] Figure 1 SEM pattern topography of the L12 type Co-Ni-Al-Ti intermetallic compound (CCIM-1 alloy in the first specific embodiment) in the embodiments of the present application;

[0023] Figure 2 Tensile curve diagram of the L12 type Co-Ni-Al-Ti intermetallic compound (CCIM-1 alloy in the first specific embodiment) in the embodiments of the present application at room temperature;

[0024] Figure 3 Tensile fracture topography diagram of the L12 type Co-Ni-Al-Ti intermetallic compound (CCIM-1 alloy in the first specific embodiment) in the embodiments of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0026] The L12 type Co-Ni-Al-Ti intermetallic compound provided by the embodiments of the present application has the chemical composition of atomic percentage of Ni: 30%-40%, Al: 8%-14%, Cr: 0-8%, Ti: 5%-10%, Ta: 0-5%, Nb: 0-5%, and Co: 18%-57%. In specific applications, the alloy elements (Co, Ni, Al, Ti, Ta, Cr, Nb) with purity of 99.99wt.% or above can be weighed according to the above element proportion, and then melted to obtain the chemical complex intermetallic compound with L12 structure (such as CCIM-1 alloy in the first specific embodiment). Figure 1), the intermetallic compound in the embodiment of the application is a Co-rich chemical complex intermetallic compound, has very excellent strength (yield strength reaches 0.89 Gpa, tensile strength reaches 1.5 GPa) and plasticity (reaches 30%), and since the melting point of pure Co is 50-150 DEG C higher than the melting point of pure Ni, this makes the melting point of the L12 type Co-Ni-Al-Ti intermetallic compound (alloy) higher than the dissolution temperature (about 1100 DEG C) of the traditional nickel-based high-temperature alloy gamma' phase, and the application can be obtained at a higher temperature.

[0027] Specifically, the intermetallic compound has at least two of Cr, Ta and Nb. The intermetallic compound can also have Cr, Ta and Nb in addition to Co, Ni, Al and Ti elements. The matrix of the intermetallic compound is L12 phase. The intermetallic compound has a sublattice site (Co, Ni, Cr) 3 (Al, Ti, Ta, Nb) which is completely different from the traditional binary and ternary single-phase intermetallic compound, and has better yield strength and tensile strength.

[0028] In a specific application, in the intermetallic compound, the Ni can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40% in terms of atomic percentage of chemical composition.

[0029] In a specific application, in the intermetallic compound, the Al can be 8%, 9%, 10%, 11%, 12%, 13% or 14%, the Cr can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8%, the Ti can be 5%, 5%, 6%, 7%, 8%, 9% or 10%, the Nb can be 0%, 1%, 2%, 3%, 4% or 5%, and the balance can be Co and unavoidable impurities.

[0030] The embodiment of the application also provides a preparation method of the L12 type Co-Ni-Al-Ti intermetallic compound, which is used for preparing the L12 type Co-Ni-Al-Ti intermetallic compound and comprises the following steps:

[0031] The melting step: the elements are weighed according to the element ratio of the chemical composition of the intermetallic compound and mixed and melted to obtain an alloy; in a specific application, the elements can be mixed and placed in a vacuum arc melting furnace for melting to obtain a molten alloy.

[0032] The cooling step: the molten alloy is cooled to obtain a cast alloy;

[0033] The homogenization treatment step: the cast alloy is subjected to homogenization treatment to obtain a homogenized alloy part;

[0034] Cyclic rolling deformation and aging treatment steps: after the alloy parts are cold-rolled and deformed, they are wrapped in iron and placed in a holding furnace for annealing for a set period of time. Rolling deformation and annealing are repeated to obtain a Co-Ni-Al-Ti system chemical complex intermetallic compound-based alloy with L12 type, wherein part of the alloy exhibits a two-phase or incomplete recrystallization state.

[0035] Specifically, in the melting step, the vacuum arc melting furnace is pumped to 10 -4 orders of magnitude, and each element is mixed and melted in the vacuum arc melting furnace. Inert protective gas (such as argon) is introduced during melting. After the alloy is completely melted and solidified into a button ingot, it is flipped and then subjected to arc vacuum arc melting. The step of flipping and then arc vacuum arc melting to solidification is repeated at least 8 times, and the melting effect is good.

[0036] Specifically, the cooling step includes pouring the molten alloy into a copper mold with a liquid cooling system (water cooling system) to obtain a strip-shaped as-cast alloy.

[0037] Specifically, in the homogenization treatment step, the as-cast alloy is wrapped in iron and homogenized at 1100°C to 1200°C for 12 hours in an inert gas protective atmosphere. The as-cast alloy is removed and air-cooled (naturally cooled), and the homogenization treatment effect is good.

[0038] Specifically, the alloy parts after the homogenization treatment step are cold-rolled and deformed, with a reduction of 20% to 30% (preferably 25%). Then, the cold-rolled alloy parts are wrapped in iron and placed in a muffle furnace at a temperature of 1100°C to 1200°C (preferably 1150°C) with inert gas (preferably argon) protection for 15 minutes for annealing. Repeat the cyclic rolling and annealing treatment until the total reduction is close to 66% (60% or more). The alloy parts are heat treated at a temperature of 1100°C to 1200°C (preferably 1150°C) for 10 to 30 minutes (preferably 15 minutes).

[0039] In specific applications, the preparation method can refer to the following:

[0040] Step S1, weigh the elements (Co, Ni, Al, Ti, Ta, Cr, Nb, B) with a purity of 99.99wt.% or higher according to the element ratio, and place them in a vacuum melting furnace;

[0041] Step S2, pump the vacuum arc melting furnace to 10 -4 orders of magnitude, and introduce inert gas (argon) into the vacuum arc melting furnace. Each element is repeatedly melted in the vacuum arc melting furnace for more than 8 times to obtain a uniformly melted cast material for melting and casting to obtain a strip-shaped as-cast alloy;

[0042] Step S3, homogenizing the as-cast alloy obtained in step S2 at 1200-1100℃ to obtain a homogenized alloy piece;

[0043] Step S4, cyclic rolling and annealing the alloy piece obtained in step S3 at 1200-1100℃ for 10-30 minutes to obtain a L12 type Co-Ni-Al-Ti intermetallic compound based alloy.

[0044] By simple arc melting and cyclic rolling process, a chemical complex intermetallic compound with L12 structure is obtained, which has a sublattice site (Co, Ni, Cr) 3 (Al, Ti, Ta, Nb) that is completely different from traditional binary and ternary single-phase intermetallic compounds, and has very excellent strength (yield strength up to 0.89 GPa, tensile strength up to 1.5 GPa) and plasticity (up to 30%), which is significantly better than traditional binary Co3Ti intermetallic compounds, such as Figure 3 As shown, the typical dimple morphology of the fracture proves the intrinsic plasticity of the material. The intermetallic compound is a Co-rich chemical complex intermetallic compound. Since the melting point of pure Co is 50-150℃ higher than that of pure Ni, the melting point of this type of alloy is higher than the dissolution temperature of the traditional nickel-based high-temperature alloy γ' phase (about 1100℃), and can be applied at higher temperatures.

[0045] In specific applications, as a first specific embodiment, the molecular expression of the chemical complex intermetallic compound alloy is Co 43 Ni 35 Al 12 Ti 10-x M x N y . Wherein (M, N = Ta, Cr, Nb elements, x = 0-8% atomic percentage), Co 43 Ni 35 Al 12 Ti6Nb4, the specific preparation method is as follows:

[0046] Arc melting: according to the proportion of alloy elements, weigh the elements (Co, Ni, Al, Ti, Ta, Cr, Nb, B) with a purity of 99.99wt.% and introduce high-purity Ar protective atmosphere in a vacuum arc melting furnace to melt the alloy. After the alloy is completely melted and solidified into a button ingot, it is turned over and then subjected to a second arc melting process. The above alloy melting steps are repeated more than 8 times to obtain a uniformly melted alloy and cast into a copper mold with a water cooling system to obtain a strip-shaped as-cast alloy;

[0047] Homogenization treatment: the as-cast alloy was wrapped in iron sheet and homogenized at 1150℃ for 12h in argon atmosphere, and then air-cooled to obtain the homogenized alloy;

[0048] Cyclic rolling deformation and aging: the obtained alloy was cold-rolled with a reduction of 25%, and then the cold-rolled alloy was wrapped in iron sheet and placed in a muffle furnace at 1150℃ for 15min in argon atmosphere. The cyclic rolling and annealing were repeated until the total reduction reached 66%, and finally the alloy was heat-treated at 1150℃ for 15min to obtain a Co-Ni-Al-Ti-based chemical complex intermetallic compound alloy with L12 type. Some of the alloys showed a two-phase or incomplete recrystallization state, Figure 1 Co 43 Ni 35 Al 12 Ti6Nb4(CCIM-1) chemical complex intermetallic compound alloy.

[0049] In a specific application, as a second specific embodiment, the molecular expression of the chemical complex intermetallic compound alloy is Co 41 Ni 35 Al 12 Ti 10-x-y M x N y (M = Ta, Cr, Nb elements, x = 0 to 4% atomic percentage). The specific preparation method is the same as the method in the first specific embodiment. The final sample of the first specific embodiment was cut into a standard bone-shaped tensile sample by wire cutting, and room temperature tensile test was carried out on an MTS testing machine. The tensile strain rate was 1×10 -3 / S. Figure 2 The mechanical tensile curve of the CCIM-1 alloy. The Co3Ti alloy (its chemical composition atomic ratio is Co 78 Ti 22 ) was used as a comparative sample. The results show that the strength and plasticity of the L12 chemical complex intermetallic compound are simultaneously improved (the yield strength reaches 800MP, the tensile strength reaches 1.5GPa), and the alloy has excellent tensile plasticity (40%), showing excellent mechanical properties. Figure 3 The rich dimples shown in FIG. 6 prove that the fracture mode of the CCIM-1 sample is plastic fracture.

[0050] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An L12 type Co-Ni-Al-Ti intermetallic compound, characterized by, The intermetallic compound has a chemical composition of atomic percentage of: Ni: 30%-40%, Al: 8%-14%, Cr: 0-8%, Ti: 5%-10%, Ta: 0-5%, Nb: 0-5%, Co: 18%-57%; and the matrix of the intermetallic compound is L12 phase.

2. The L12-type Co-Ni-Al-Ti intermetallic compound as described in claim 1, characterized in that, The intermetallic compound has at least two of Cr, Ta and Nb.

3. A method for producing an L12 type Co-Ni-Al-Ti intermetallic compound, characterized by, A method for preparing an L12 type Co-Ni-Al-Ti intermetallic compound as claimed in claim 1 or 2, comprising the following steps: a smelting step of weighing and mixing elements according to the element ratio of the chemical composition of the intermetallic compound to obtain an alloy; a cooling step of obtaining a cast alloy after cooling the alloy; a homogenization treatment step of obtaining a homogenized alloy by homogenizing the cast alloy; a cyclic rolling deformation and aging treatment step of annealing the alloy after cold rolling deformation, wrapping in iron sheet and placing in a holding furnace for a set time period, and repeating the rolling deformation and annealing.

4. The method of producing an L12 type Co-Ni-Al-Ti intermetallic compound according to claim 3, wherein In the smelting step, each element is mixed and smelted in a vacuum arc smelting furnace, and inert protective gas is introduced during smelting. After the alloy is completely melted and solidified into a button ingot, it is turned over and then subjected to arc vacuum arc smelting. The step of arc vacuum arc smelting after turning over is repeated at least 8 times.

5. The method for preparing an L12-type Co-Ni-Al-Ti intermetallic compound as described in claim 3, characterized in that, The cooling step includes pouring the alloy into a copper mold with a liquid cooling system to obtain a cast alloy in the form of a strip.

6. The method for preparing an L12-type Co-Ni-Al-Ti intermetallic compound as described in claim 3, characterized in that, In the homogenization treatment step, the cast alloy is wrapped in iron sheet and homogenized at 1100-1200°C for 12h in an inert gas protective atmosphere, and the cast alloy is taken out and air cooled.

7. The method of producing an L12 type Co-Ni-Al-Ti intermetallic compound according to claim 6, wherein The alloy after the homogenization treatment step is subjected to cold rolling deformation with a reduction of 20%-30%, then the cold-rolled alloy is wrapped in iron sheet and placed in a muffle furnace with a temperature of 1100-1200°C and inert gas protection for 15min annealing. The cyclic rolling and annealing treatment is repeated until the total reduction approaches 66%, and the alloy is heat treated at a temperature of 1100-1200°C for 10-30min.

8. The method for preparing an L12-type Co-Ni-Al-Ti intermetallic compound as described in claim 6, characterized in that, The homogenization treatment temperature of the cast alloy is 1150°C.

9. The method for preparing an L12-type Co-Ni-Al-Ti intermetallic compound as described in claim 7, characterized in that, The alloy is heat treated at a temperature of 1150°C for 15min.

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