Nano eutectoid lamellar cast eutectic high-entropy alloy and preparation method thereof

Abstract

The general formula of the eutectic high-entropy alloy is NiaCobFecSidMe, M is a microelement, a is larger than or equal to 15%, b is larger than or equal to 15%, c is larger than or equal to 0% and smaller than or equal to 20%, d is larger than or equal to 15% and smaller than or equal to 25%, e is larger than or equal to 0%, a + b + c + d + e = 100%, and a, b, c, d and e are the molar percentages of the corresponding elements respectively. The eutectic high-entropy alloy is prepared by adopting a suspension induction melting method. The microstructure of the eutectic high-entropy alloy is in a special plate lamellar morphology and has a nanoscale eutectoid lamellar structure, and the microstructure of the eutectic high-entropy alloy is composed of a (Fe, Co and Ni) face-centered cubic FCC solid solution and a (Fe, Co and Ni) 31Si12 type intermetallic compound. The eutectic high-entropy alloy is small in interlamellar spacing and has excellent casting fluidity, the addition of the Si element is beneficial to reducing the overall density and manufacturing cost of the alloy, meanwhile, the oxidation resistance of the alloy is improved, and the eutectic high-entropy alloy has wide application prospects in the fields of aerospace, mechanical industry and the like.

Description

Technical Field

[0001] The invention relates to the technical field of high entropy alloys, and in particular to a nano-eutectoid lamellar casting eutectic high entropy alloy and a preparation method thereof. Background Art

[0002] Eutectic high entropy alloys have the advantages of both traditional eutectic alloys and high entropy alloys, and usually exhibit excellent comprehensive properties, such as high oxidation resistance, good high-temperature creep resistance, excellent casting fluidity and uniform microstructure, and improve the shortcomings of high entropy alloys.

[0003] CN 114686743A discloses a Co-Cr-Fe-Ni-VB-Si eutectic high entropy alloy, the general formula of which is Co a Cr b Fe c Ni d V e B f Si g , where 10%≤a≤20%, 10%≤b≤20%, 10%≤c≤20%, 30%≤d≤40%, 10%≤e≤15%, 5%≤f≤10% and 1%≤g≤5%, and a+b+c+d+e+f+g=100%, a, b, c, d, e, f and g are the molar percentages of the corresponding elements. In this patent, on the one hand, the Si element is added at a content of less than 5%, and cannot be used as the main element of the eutectic high entropy alloy. On the other hand, the molar ratio of Co, Cr, Fe and Ni as the main element is Co:Cr:Fe:Ni=1:1:1:1 / 2, and the molar ratio of V:B:Si is 6:3:1, which are all fixed ratios, resulting in the change of the Si element content of the eutectic high entropy alloy in this patent must be synchronized with the V and B elements.

[0004] CN 114657438A discloses a Co-Cr-Fe-Ni-Ti-Si eutectic high entropy alloy, the general formula of which is Co a Cr b Fe c Ni d Ti e Si f , where 13%≤a≤20%, 0%≤b≤20%, 13%≤c≤20%, 30%≤d≤40%, 8%≤e≤12% and 8%≤f≤17%, and a+b+c+d+e+f=100%, a, b, c, d, e and f are the molar percentages of the corresponding elements. In this patent, the molar ratio of Co, Cr, Fe and Ni as the main elements is also Co:Cr:Fe:Ni=1:1:1:1 / 2. Cr may not be added to the alloy, but the main element content still needs to be kept at a fixed ratio, and the specific Si content is 8%≤f≤17%.

[0005] In terms of alloy composition, the current high entropy alloy composition design is basically based on metal elements, and there are few reports on the design of non-metallic elements as the main element. In the above two patents, Si elements are added to the alloy system, but not as the main element, and there are still limitations such as fixed main element ratio and low Si content. In the composition design of binary eutectic alloys, the combination of metal and non-metallic elements has been widely studied and applied, such as Ni-Si, Al-Si, Fe-C, etc. Inorganic non-metals are lighter and cheaper, which is conducive to reducing the overall density and manufacturing cost of the alloy, and their own characteristics can also make the alloy have the potential to improve the oxidation resistance. Therefore, designing eutectic high entropy alloys with higher non-metallic element Si content is a direction worthy of research. Summary of the invention

[0006] The first object of the present invention is to provide a nano-eutectoid lamellar casting eutectic high entropy alloy, wherein the Si content is not less than 15%.

[0007] The second object of the present invention is to provide a method for preparing the above-mentioned nano-eutectoid lamellar cast eutectic high entropy alloy.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a nano-eutectoid lamellar casting eutectic high entropy alloy, the general formula of the eutectic high entropy alloy is Ni a Co b Fe c Si d M e , M is a trace element, wherein a≥15%, b≥15%, 0%≤c≤20%, 15%≤d≤25%, e≥0%, and a+b+c+d+e=100%, a, b, c, d, e are the molar percentages of the corresponding elements respectively;

[0010] Wherein, M is one or more of Al, Mn, Nb, Mo, Ta, La, Ce, and Sm.

[0011] In the present invention, the general formula of Ni-Co-Fe-Si eutectic high entropy alloy is Ni a Co b Fe c Si d M e. In terms of the composition of the alloy system, the alloy system is designed in accordance with the principle of equimolar ratio and Si element as the main element. The ratio of Fe to Co and Ni elements is not fixed, and the Fe content can vary in the range of 0% to 20%. The alloy structure is a consistent special lamellar lamellar structure. In addition, the Si content in the alloy system is 15%≤Si≤25%, which is higher than the Si content in the prior art (CN 114686743A, CN 114657438A). In terms of the microstructure of the alloy, the alloy has a special nano-scale eutectoid lamellar structure on the basis of a special lamellar lamellar structure. In terms of element types, the alloy system contains not only transition metal elements and non-metallic elements, but also rare earth elements are added to improve the alloy structure and improve mechanical and antioxidant properties.

[0012] In a second aspect, the present invention provides a method for preparing a nano-eutectoid lamellar casting eutectic high entropy alloy, comprising the following steps:

[0013] (1) removing the oxide scale on the surface of the alloy raw material by physical or chemical methods, and using ethanol ultrasonic cleaning to clean the alloy raw material;

[0014] (2) According to the eutectic high entropy alloy Ni a Co b Fe c Si d M e The alloy raw materials are sequentially placed into a quartz test tube in a suspension melting furnace according to the molar ratio of each component;

[0015] (3) After the suspension smelting furnace is evacuated, an inert gas is filled into the suspension smelting furnace;

[0016] (4) Smelting to obtain a eutectic high entropy alloy with a lamellar structure.

[0017] In step (1), the physical method is one or more of sandpaper polishing, sandblasting, and laser cleaning, and the chemical method is immersion acid cleaning or immersion alkali cleaning, using ethanol ultrasonic cleaning for 15 to 20 minutes.

[0018] In step (1), the purity of the alloy raw material is 99.5% to 100%.

[0019] In step (3), the vacuum degree of the suspension smelting furnace is drawn to 6×10 -3 Pa~5×10 -3 After the inert gas is filled in, the pressure in the furnace is made to reach 0.05-0.06MPa.

[0020] By adjusting the ratio of the main group elements Ni, Co, Fe, and Si, mainly adjusting the ratio of the non-metallic element Si, a eutectic high entropy alloy is obtained.

[0021] By adjusting the content of trace elements, the alloy structure and properties can be enhanced.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The high entropy alloy provided by the present invention is a eutectic composition, has a special plate-like lamellar morphology, and has a special nano-scale eutectoid lamellar structure, and its microstructure is composed of (Fe, Co, Ni) face-centered cubic FCC solid solution and (Fe, Co, Ni) 31 Si 12 Type of intermetallic compound composition, uniform organizational structure;

[0024] 2. The high entropy alloy provided by the present invention has a high Si content, which reduces the overall density and manufacturing cost of the alloy, thereby improving the oxidation resistance. At the same time, it has a low melting point, good fluidity, and excellent casting performance. It can be directly melted under low vacuum and inert protective atmosphere. The preparation method is simple and easy to operate, and can be used in large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The SEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1, the composition of which is Ni 34 Co 34 Fe 10.2 Si 21.8 ;

[0026] Figure 2 The XRD spectrum of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1, the composition of which is Ni 34 Co 34 Fe 10.2 Si 21.8 ;

[0027] Figure 3 TEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1, whose components are Ni 34 Co 34 Fe 10.2 Si 21.8 ;

[0028] Figure 4 The solidification temperature curve of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1, wherein the composition is Ni 34 Co 34 Fe 10.2 Si 21.8 ;

[0029] Figure 5This is the SEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 2, whose components are Ni 33.7 Co 33.7 Fe 10.11 Si 22.5 ;

[0030] Figure 6 The XRD spectrum of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 2, the composition of which is Ni 33.7 Co 33.7 Fe 10.11 Si 22.5 ;

[0031] Figure 7 This is the SEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 3, whose components are Ni 34 Co 34 Fe 8.2 Si 21.8 Ce 2 ;

[0032] Figure 8 The XRD spectrum of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 3, the composition of which is Ni 34 Co 34 Fe 8.2 Si 21.8 Ce 2 ;

[0033] Fig. 9 This is the SEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 4, whose components are Ni 39.1 Co 39.1 Si 21.8 . DETAILED DESCRIPTION

[0034] The present invention discloses a nano-eutectoid lamellar casting eutectic high entropy alloy, wherein the general formula of the eutectic high entropy alloy is Ni a Co b Fe c Si d M e , M is a trace element, wherein a≥15%, b≥15%, 0%≤c≤20%, 15%≤d≤25%, e≥0%, and a+b+c+d+e=100%, a, b, c, d, e are the molar percentages of the corresponding elements respectively;

[0035] Wherein, M is one or more of Al, Mn, Nb, Mo, Ta, La, Ce, and Sm.

[0036] A method for preparing a nano-eutectoid lamellar casting eutectic high entropy alloy comprises the following steps:

[0037] (1) Using a physical method or a chemical method to remove the oxide scale on the surface of the alloy raw material, and using ethanol ultrasonic cleaning for 15 to 20 minutes; wherein the physical method is one or more of sandpaper polishing, sandblasting, and laser cleaning, and the chemical method is immersion acid cleaning or immersion alkaline cleaning; the purity of the alloy raw material is 99.5% to 100%.

[0038] (2) placing the alloy raw materials into a quartz test tube in a suspension melting furnace in sequence according to the molar ratio of each component of the eutectic high entropy alloy;

[0039] (3) When the vacuum degree of the suspension smelting furnace is reduced to 6×10 -3 Pa~5×10 -3 After the inert gas is filled in, the pressure in the furnace is made to reach 0.05-0.06MPa.

[0040] (4) Smelting to obtain a eutectic high entropy alloy with a lamellar structure.

[0041] In the present invention, by adjusting the ratio of the main group elements Ni, Co, Fe, and Si, mainly adjusting the ratio of the non-metallic element Si, a eutectic high entropy alloy is obtained. By adjusting the content of trace elements, the alloy structure and properties are enhanced.

[0042] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] A eutectic high entropy alloy, the components of which are designed to be Ni in molar ratio a Co b Fe c Si d M e , M is a trace element. Among them, a = 34%, b = 34%, c = 10.2%, d = 21.8%, e = 0%, that is, Ni 34 Co 34 Fe 10.2 Si 21.8 .

[0045] Eutectic High Entropy Alloy Ni 34 Co 34 Fe 10.2 Si 21.8 The preparation method comprises the following steps:

[0046] (1) The oxide scale on the surface of the raw material was removed by sandpaper polishing, and the alloy raw material was cleaned by ethanol ultrasonic cleaning for 20 minutes;

[0047] (2) According to the eutectic high entropy alloy Ni 34 Co 34 Fe 10.2 Si 21.8 The alloy raw materials are placed in a quartz test tube in a suspension melting furnace according to the proportion of each component;

[0048] (3) Wait until the vacuum degree reaches 6×10 -3 After the furnace is filled with argon gas, the pressure in the furnace is made to reach 0.05MPa;

[0049] (4) Melting to obtain a eutectic high entropy alloy with uniform microstructure.

[0050] Figure 1 The SEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1, the composition of which is Ni 34 Co 34 Fe 10.2 Si 21.8 The eutectic high entropy alloy presents a lamellar morphology, with a plate length of up to 100μm. At the same time, neatly arranged eutectic lamellar structures can be seen in the figure.

[0051] Figure 2 The XRD pattern of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1 shows that the eutectic high entropy alloy is composed of (Fe, Co, Ni) face-centered cubic FCC solid solution and (Fe, Co, Ni) 31 Si 12 Type of intermetallic compound composition.

[0052] Figure 3 This is the TEM microscopic morphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1. It can be clearly seen from the figure that the thickness of the neatly arranged eutectic lamellae is about 100 nm.

[0053] Figure 4 The solidification temperature curve of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 1 shows that the alloy underwent eutectic and eutectoid reactions at 1160°C and 1000°C, respectively.

[0054] Example 2

[0055] A eutectic high entropy alloy, the components of which are designed to be Ni in molar ratio a Co b Fe c Si d M e , M is a trace element. Among them, a = 33.7%, b = 33.7%, c = 10.11%, d = 22.5%, e = 0%, that is, Ni 33.7 Co 33.7 Fe10.11 Si 22.5 .

[0056] Eutectic High Entropy Alloy Ni 33.7 Co 33.7 Fe 10.11 Si 22.5 The preparation method comprises the following steps:

[0057] (1) The oxide scale on the surface of the raw material was removed by sandpaper polishing, and the alloy raw material was cleaned by ethanol ultrasonic cleaning for 20 minutes;

[0058] (2) According to the eutectic high entropy alloy Ni 33.7 Co 33.7 Fe 10.11 Si 22.5 The alloy raw materials are placed in a quartz test tube in a suspension melting furnace according to the proportion of each component;

[0059] (3) Wait until the vacuum degree reaches 6×10 -3 After the furnace is filled with argon gas, the pressure in the furnace is made to reach 0.05MPa;

[0060] (4) Melting to obtain a eutectic high entropy alloy with uniform microstructure.

[0061] Figure 5 This is the SEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 2, whose components are Ni 33.7 Co 33.7 Fe 10.11 Si 22.5 The eutectic high entropy alloy presents a lamellar hypereutectic morphology, and neatly arranged eutectoid lamellar structures can be seen in the figure.

[0062] Figure 6 The XRD spectrum of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 2 shows that the eutectic high entropy alloy is also composed of (Fe, Co, Ni) face-centered cubic FCC solid solution and (Fe, Co, Ni) 31 Si 12 Type of intermetallic compound composition.

[0063] Example 3

[0064] A eutectic high entropy alloy, the components of which are designed to be Ni in molar ratio a Co b Fe c Si d M e , M is a trace element. Among them, a = 34%, b = 34%, c = 8.2%, d = 21.8%, e = 2%, M is cerium (Ce) or Ni 34 Co34 Fe 8.2 Si 21.8 Ce 2 .

[0065] Eutectic High Entropy Alloy Ni 34 Co 34 Fe 8.2 Si 21.8 Ce 2 The preparation method comprises the following steps:

[0066] (1) The oxide scale on the surface of the raw material was removed by sandpaper polishing, and the alloy raw material was cleaned by ethanol ultrasonic cleaning for 20 minutes;

[0067] (2) According to the eutectic high entropy alloy Ni 34 Co 34 Fe 8.2 Si 21.8 Ce 2 The alloy raw materials are placed in a quartz test tube in a suspension melting furnace according to the proportion of each component;

[0068] (3) Wait until the vacuum degree reaches 6×10 -3 After the furnace is filled with argon gas, the pressure in the furnace is made to reach 0.05MPa;

[0069] (4) Melting to obtain a eutectic high entropy alloy with uniform microstructure.

[0070] Figure 7 This is the SEM micromorphology of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 3, whose components are Ni 34 Co 34 Fe 8.2 Si 21.8 Ce 2 The eutectic high entropy alloy also presents a lamellar morphology. At the same time, neatly arranged eutectic lamellar structures can be seen in the figure. The addition of Ce effectively shortens the length of the lamellar sheets, which is beneficial to the mechanical properties.

[0071] Figure 8 The XRD spectrum of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 3 shows that the eutectic high entropy alloy is composed of (Fe, Co, Ni, Ce) face-centered cubic FCC solid solution and (Fe, Co, Ni, Ce) 31 Si 12 Type of intermetallic compound composition.

[0072] Example 4

[0073] A eutectic high entropy alloy, the components of which are designed to be Ni in molar ratio a Co b Fec Si d M e , M is a trace element. Among them, a = 39.1%, b = 39.1%, c = 0%, d = 21.8%, e = 0%, that is, Ni 39.1 Co 39.1 Si 21.8 .

[0074] Eutectic High Entropy Alloy Ni 39.1 Co 39.1 Si 21.8 The preparation method comprises the following steps:

[0075] (1) The oxide scale on the surface of the raw material was removed by sandpaper polishing, and the alloy raw material was cleaned by ethanol ultrasonic cleaning for 20 minutes;

[0076] (2) According to the eutectic high entropy alloy Ni 39.1 Co 39.1 Si 21.8 The alloy raw materials are placed in a quartz test tube in a suspension melting furnace according to the proportion of each component;

[0077] (3) Wait until the vacuum degree reaches 6×10 -3 After the furnace is filled with argon gas, the pressure in the furnace is made to reach 0.05MPa;

[0078] (4) Melting to obtain a eutectic high entropy alloy with uniform microstructure.

[0079] Fig. 9 The metallographic microstructure of the Ni-Co-Fe-Si eutectic high entropy alloy prepared in Example 4, the composition of which is Ni 39.1 Co 39.1 Si 21.8 The alloy exhibits a lamellar eutectic morphology, and nanoscale eutectic lamellae similar to those in Example 1 can be clearly seen.

[0080] In summary, the eutectic high entropy alloy described in the present invention not only exhibits excellent casting fluidity and uniform organizational structure, but also has potential wear resistance, oxidation resistance and corrosion resistance. It has the potential to be used as a liquid molding raw material in the fields of aerospace, instrumentation, electronic communications, and mechanical industries, among which liquid molding includes 3D printing and casting.

[0081] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A nano-eutectoid lamellar casting eutectic high entropy alloy, characterized in that: The general formula of the eutectic high entropy alloy is Ni a Co b Fe c Si d M e , M is a trace element, and M is one or more of Al, Mn, Nb, Mo, Ta, La, Ce, and Sm; wherein a≥15%, b≥15%, 0%≤c≤20%, 15%≤d≤25%, e≥0%, and a+b+c+d+e=100%, and a, b, c, d, and e are the molar percentages of the corresponding elements, respectively.

2. A method for preparing the nano-eutectoid lamellar casting eutectic high entropy alloy according to claim 1, characterized in that: The following steps are involved: (1) removing the oxide scale on the surface of the alloy raw material by physical or chemical methods, and using ethanol ultrasonic cleaning to clean the alloy raw material; (2) According to the eutectic high entropy alloy Ni a Co b Fe c Si d M e The alloy raw materials are sequentially placed into a quartz test tube in a suspension melting furnace according to the molar ratio of each component; (3) After the suspension smelting furnace is evacuated, an inert gas is filled into the suspension smelting furnace; (4) Smelting to obtain a eutectic high entropy alloy with a lamellar structure.

3. The method for preparing the nano-eutectoid lamellar casting eutectic high entropy alloy according to claim 2, characterized in that: In step (1), the physical method is one or more of sandpaper polishing, sandblasting, and laser cleaning, and the chemical method is immersion acid cleaning or immersion alkali cleaning, using ethanol ultrasonic cleaning for 15 to 20 minutes.

4. The method for preparing the nano-eutectoid lamellar casting eutectic high entropy alloy according to claim 2, characterized in that: In step (1), the purity of the alloy raw material is 99.5% to 100%.

5. The method for preparing the nano-eutectoid lamellar casting eutectic high entropy alloy according to claim 2, characterized in that: In step (3), the vacuum degree of the suspension smelting furnace is drawn to 6×10 -3 Pa~5×10 -3 After the inert gas is filled in, the pressure in the furnace is made to reach 0.05-0.06MPa.

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