High-strength micro-nano hierarchical pore single-phase beta-NiAl (Cr) intermetallic compound and preparation method thereof

Abstract

The invention discloses a high-strength micro-nano hierarchical pore single-phase beta-NiAl (Cr) intermetallic compound. A preparation method comprises the following steps: 1, pressing beta-NiAl (Cr) alloy powder, sintering in vacuum, and cutting to obtain slices; 2, cleaning and purifying treatment; 3, carrying out electrochemical treatment by taking the treated thin sheet as a working electrode, and cleaning and drying; 4, vacuum heat treatment; 5, cleaning and drying; the intermetallic compound has a micro-nano two-stage pore structure with a first-stage pore size of 10 [mu] m-25 [mu] m and a second-stage pore size of 10 nm-100 nm. The high-strength and high-toughness porous single-phase beta-NiAl (Cr) intermetallic compound is prepared through a powder metallurgy method, micron pores are formed, Al is selectively dissolved through electrochemical treatment, nano pores are formed, the high-strength micro-nano hierarchical pore single-phase beta-NiAl (Cr) intermetallic compound is obtained, and the high-strength micro-nano hierarchical pore single-phase beta-NiAl (Cr) intermetallic compound is suitable for the fields of filtration, separation, ion exchange, hydrogen evolution electrodes, catalyst carriers and the like.

Description

Technical Field

[0001] This invention belongs to the field of metal micro-nano hierarchical porous intermetallic compound materials and their preparation technology, specifically relating to a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound and its preparation method. Background Technology

[0002] Porous intermetallic compounds β-NiAl possess excellent properties such as low density, high melting point, high thermal conductivity, good high-temperature resistance, and high electrical conductivity, making them a promising new type of porous material. They are ideal carriers for automotive exhaust purifiers and filter media for particulate filters, and are expected to find applications in areas such as vehicle exhaust purification and high-temperature filtration, as well as industrial wastewater treatment.

[0003] In recent years, the preparation of porous β-NiAl intermetallic compounds has seen significant development. The most common methods are self-propagating combustion and solid-state diffusion sintering. However, the porous β-NiAl intermetallic compounds prepared by these methods suffer from poor plasticity and toughness, and insufficient high-temperature strength, due to the introduction of pore-forming agents during the reaction process, resulting in extremely high macropore porosity and uneven pore size distribution. Furthermore, the non-uniform composition leads to the coexistence of multiphase intermetallic compounds (Ni₂Al₃, NiAl₃) and the Al phase. Therefore, the controllability of the composition, pore structure, and morphology of porous intermetallic compounds is very poor.

[0004] Traditional Raney nickel is a nanoporous, aluminum-rich NiAl intermetallic compound, a solid heterogeneous catalyst composed of fine-grained nickel-aluminum alloys. Its preparation typically involves fusing equal masses of nickel and aluminum to produce a multiphase compound consisting of three phases: Ni₂Al₃, NiAl₃, and Al-NiAl₃ eutectic phases. These multiphase compounds are then used as precursors to leach aluminum in an alkaline solution to obtain a nanoporous structure. However, this alkaline leaching method is ineffective for the β-NiAl phase (Al content 12–30 wt%), and it fails to produce nanopores. Therefore, preparing nanoscale porous structures in the β-NiAl phase remains a significant challenge.

[0005] Hierarchical porous structures typically possess two or more pore sizes. These structures not only increase the overall specific surface area of ​​the material but also enhance mass transfer within the material. Hierarchical porous structures have attracted significant attention in fields such as catalysis, adsorption, separation media, and storage supports. Therefore, optimizing the overall performance of single-phase porous β-NiAl and functionalizing hierarchical porous structures are crucial to expanding their application areas. Summary of the Invention

[0006] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compounds. This method employs powder metallurgy to prepare high-strength and high-toughness porous single-phase β-NiAl(Cr) intermetallic compounds and form micron-sized pores. Combined with electrochemical treatment to selectively dissolve Al, nanopores are prepared, resulting in high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compounds with uniform composition, simple phase structure, and controllable pore structure and morphology. This solves the current problem that nanoporous structures can only be prepared in high-alumina Ni2Al3, NiAl3, and Al-NiAl3 phases, and cannot be obtained in low-alumina β-NiAl.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound, characterized in that the method includes the following steps: Step 1: Fill β-NiAl(Cr) alloy powder into a mold, press it into shape using a press, and then perform vacuum sintering to obtain a porous single-phase β-NiAl(Cr) intermetallic compound, which is then processed into a porous single-phase β-NiAl(Cr) intermetallic compound sheet. Step 2: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet from Step 1 in an acid solution for cleaning, then ultrasonically clean it in deionized water, acetone and anhydrous ethanol in sequence, and then purify it under a nitrogen atmosphere to obtain the treated porous single-phase β-NiAl(Cr) intermetallic compound sheet. Step 3: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet treated in Step 2 into the electrolyte as the working electrode, with a platinum electrode as the cathode and an Ag / AgCl electrode as the reference electrode, and perform electrochemical treatment under an applied voltage. Then, take out the electrochemically treated porous single-phase β-NiAl(Cr) intermetallic compound sheet and perform ultrasonic cleaning and vacuum drying. Step 4: Perform vacuum heat treatment on the porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum drying in Step 3; Step 5: The porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum heat treatment in Step 4 is ultrasonically cleaned in deionized water and anhydrous ethanol respectively, and then vacuum dried to obtain a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound.

[0008] The above-mentioned method for preparing a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is characterized in that the porous single-phase β-NiAl(Cr) intermetallic compound in step one is a Ni-16Cr-xAl alloy with a Cr mass content of 16% and an Al mass content of 13%~20%, and the phase is a single-phase β-NiAl(Cr).

[0009] The above-mentioned method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is characterized in that the particle size of the β-NiAl(Cr) alloy powder in step one is 100~400 mesh, the pressing pressure is 100MPa~250MPa, and the vacuum degree of the vacuum sintering is 10... -2 Pa ~10 -3 The temperature is 1100℃~1300℃, the sintering time is 2h, and the thickness of the porous single-phase β-NiAl(Cr) intermetallic compound sheet is 0.1mm~1mm.

[0010] The above-mentioned method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is characterized in that, in step two, the acid in the acid solution is selected from HNO3, HCl, H2SO4 and oxalic acid, the acid solution concentration is 0.2M~2M, the acid solution temperature is 40℃~80℃, and the washing time in the acid solution is 15min~60min; the ultrasonic washing time is 60min; the pressure of the nitrogen atmosphere is 0.6Pa~1.0Pa, and the purification time is 20min~60min.

[0011] The above-mentioned method for preparing a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is characterized in that the electrolyte in step three is a NaOH or KOH solution with a concentration of 1M~4M, the applied voltage is 0.5V~3V, and the electrochemical treatment time is 60min~240min. The preparation method of the above-mentioned high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is characterized in that the vacuum heat treatment in step four is performed at a temperature of 200℃~400℃ for a time of 30min~180min.

[0012] The preparation method of the above-mentioned high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is characterized in that the ultrasonic cleaning time in step five is 60 min.

[0013] The preparation method of the above-mentioned high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is characterized in that the thickness of the high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound in step five is 0.1 mm to 1 mm.

[0014] Meanwhile, this invention also discloses a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound prepared by the method described above. The compound is characterized by having a micro-nano hierarchical pore structure, comprising primary pores formed by the stacking of powder particles with a size of 10 μm to 25 μm, and secondary pores that are uniformly distributed, have a uniform pore size, are through-holes, and have a size of 10 nm to 100 nm. The porosity is 23% to 45%. The strength of this micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is 1468 MPa to 1980 MPa, and the phase is a single-phase β-NiAl(Cr) with a solid solution mass fraction of 16% Cr.

[0015] Compared with the prior art, the present invention has the following advantages: 1. This invention uses β-NiAl(Cr) alloy powder as raw material to prepare a high-strength and high-toughness porous single-phase β-NiAl(Cr) intermetallic compound by powder metallurgy, forming micron-sized pores. Then, electrochemical treatment is used to selectively dissolve Al to achieve the preparation of nanopores, thus obtaining a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound with uniform composition, simple phase structure, and controllable pore structure and morphology.

[0016] 2. This invention uses β-NiAl(Cr) alloy powder as raw material. Since Cr is dissolved in NiAl to form a single phase, there are no other intermediate compounds present and the composition is uniform. This ensures that the micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound of the product is still a single-phase structure, thereby enabling the product to obtain uniform pore size and pore morphology, avoiding crack generation and pulverization caused by uneven distribution of corrosion stress between multiple phases.

[0017] 3. Compared to conventionally prepared porous NiAl intermetallic compounds using combustion reaction synthesis or solid-phase diffusion methods, which suffer from poor ductility and toughness due to the coexistence of multiple phases (NiAl3, Ni3Al, Ni solid solutions, etc.) leading to uneven composition and large differences in pore size distribution (from a few micrometers to hundreds of micrometers), this invention, by selecting the particle size of β-NiAl(Cr) alloy powder and controlling powder metallurgy process parameters, obtains first-order pores (micrometer pores) with precise control over pore structure and pore distribution while ensuring the single-phase structure. This improves the overall strength and toughness of micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compounds.

[0018] 4. The present invention employs a constant voltage-controlled electrochemical dealloying method, which can precisely control the dissolution rate of Al, increase the dissolution force of Al, and ensure that the dissolution of Al continues. This results in the formation of uniformly distributed nanopores on the surface and inside of the porous single-phase β-NiAl(Cr) intermetallic compound. The pore structure has a specific orientation and the nanopores are uniformly distributed, avoiding the problems of difficult control of the dealloying process between multiple phases and the difficulty in maintaining the integrity of the porous structure and low strength in the preparation of Raney nickel in the prior art.

[0019] 5. This invention, through electrochemical treatment combined with subsequent heat treatment to expand the pores, not only forms uniformly distributed nano-through pores on the surface and inside of porous single-phase β-NiAl(Cr) intermetallic compounds, but also allows for the control of the size and depth of the nanopores.

[0020] 6. The micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound prepared by this invention has the characteristics of low cost, high efficiency, small and uniform pore size distribution, and high strength, and can be widely used in engineering fields such as filtration, separation, ion exchange, hydrogen evolution electrode, and catalyst support.

[0021] 7. The high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound prepared by this invention, when used as a carrier for motor vehicle exhaust gas purifiers, not only meets the requirements for carrier strength, toughness, thermal shock resistance, and thermal stability, but also greatly promotes the catalytic conversion efficiency of motor vehicle cold-start exhaust pollutants due to its extremely high thermal conductivity. When used as a filter element for diesel vehicle exhaust particulate traps, this high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound can meet the requirements for filter element mechanical strength and thermal shock resistance, and solve the problem of thermal fatigue damage during filter element regeneration, ensuring service life and promoting the practical application of diesel vehicle exhaust aftertreatment technology.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the preparation process of the present invention.

[0024] Figure 2 This is a photograph of a porous single-phase β-NiAl(Cr) intermetallic compound thin sheet prepared in Example 1 of the present invention.

[0025] Figure 3 The image shows the XRD pattern of the porous single-phase β-NiAl(Cr) intermetallic compound thin film prepared in Example 1 of this invention.

[0026] Figure 4 SEM images of the high-strength porous single-phase β-NiAl(Cr) intermetallic compound sheet prepared in Example 1 of this invention before and after electrochemical treatment. Detailed Implementation

[0027] Example 1 like Figure 1 As shown, this embodiment includes the following steps: Step 1: β-NiAl(Cr) alloy powder with a particle size of 300-400 mesh, prepared by atomization, is loaded into a mold and pressed into shape using a press at 250 MPa. Then, it is placed into a material boat for vacuum sintering at a vacuum degree of 10. -2 Pa~10 - 3 A porous single-phase β-NiAl(Cr) intermetallic compound was obtained by sintering at 1300℃ for 2 hours, followed by wire cutting to obtain a 1mm thick porous single-phase β-NiAl(Cr) intermetallic compound sheet. Figure 2 As shown; The porous single-phase β-NiAl(Cr) intermetallic compound is a Ni-16Cr-20Al alloy with a Cr mass content of 16% and an Al mass content of 20%, and the phase is a single-phase β-NiAl(Cr). Step 2: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet from Step 1 in an acid solution of HNO3 and H2SO4, both at a concentration of 0.2M, for 15 min. The acid solution temperature is 80℃. Then, ultrasonically clean it in deionized water, acetone, and anhydrous ethanol for 60 min in sequence. Finally, purify it under a nitrogen atmosphere of 0.6 Pa to 1.0 Pa for 60 min to obtain the treated porous single-phase β-NiAl(Cr) intermetallic compound sheet. Step 3: The porous single-phase β-NiAl(Cr) intermetallic compound sheet treated in Step 2 is immersed in 2M NaOH electrolyte as the working electrode, with a platinum electrode as the cathode and an Ag / AgCl electrode as the reference electrode. Electrochemical treatment is carried out for 240 min under an applied voltage of 3V. Then, the porous single-phase β-NiAl(Cr) intermetallic compound sheet after electrochemical treatment is taken out and ultrasonically cleaned and vacuum dried. Step 4: Vacuum heat treatment is performed on the porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum drying in Step 3 at a temperature of 400℃ for 30 min. Step 5: The porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum heat treatment in Step 4 is ultrasonically cleaned in deionized water and anhydrous ethanol for 60 min respectively, and then vacuum dried to obtain a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound with a thickness of 1 mm.

[0028] Figure 3The XRD pattern of the porous single-phase β-NiAl(Cr) intermetallic compound prepared in this embodiment is shown below. Figure 3 It can be seen that the phase of this porous single-phase β-NiAl(Cr) intermetallic compound is a single-phase β-NiAl(Cr), with no other phases.

[0029] Figure 4 SEM images of the high-strength porous single-phase β-NiAl(Cr) intermetallic compound sheets prepared in this embodiment before and after electrochemical treatment. Figure 4 It can be seen that the porous single-phase β-NiAl(Cr) intermetallic compound sheet has primary pores with a size of 10 μm before electrochemical treatment, and after electrochemical treatment, it forms secondary pores with uniform distribution, uniform pore size and through-holes with a size of 100 nm.

[0030] In step two of this embodiment, the acid solution can also be prepared from acids selected from HNO3, HCl, H2SO4 and oxalic acid, other than HNO3 and H2SO4; the NaOH electrolyte in step three can also be replaced with KOH electrolyte.

[0031] Example 2 like Figure 1 As shown, this embodiment includes the following steps: Step 1: β-NiAl(Cr) alloy powder with a particle size of 100-200 mesh, prepared by atomization, is loaded into a mold and pressed into shape using a press at 100 MPa. Then, it is placed into a material boat for vacuum sintering at a vacuum degree of 10... -2 Pa~10 - 3 A porous single-phase β-NiAl(Cr) intermetallic compound was obtained by sintering at 1100℃ for 2 hours, and then wire-cut to obtain a porous single-phase β-NiAl(Cr) intermetallic compound sheet with a thickness of 0.1 mm. The porous single-phase β-NiAl(Cr) intermetallic compound is a Ni-16Cr-15Al alloy with a Cr mass content of 16% and an Al mass content of 15%, and the phase is a single-phase β-NiAl(Cr). Step 2: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet from Step 1 in an acid solution of HNO3 and H2SO4, both at a concentration of 1M, for 60 min. The acid solution temperature is 60℃. Then, ultrasonically clean the sheet in deionized water, acetone, and anhydrous ethanol for 60 min in sequence. Finally, purify the sheet under a nitrogen atmosphere of 0.6 Pa to 1.0 Pa for 20 min to obtain the treated porous single-phase β-NiAl(Cr) intermetallic compound sheet. Step 3: The porous single-phase β-NiAl(Cr) intermetallic compound sheet treated in Step 2 is immersed in 3M NaOH electrolyte as the working electrode, with a platinum electrode as the cathode and an Ag / AgCl electrode as the reference electrode. Electrochemical treatment is carried out for 360 min under an applied voltage of 1V. Then, the porous single-phase β-NiAl(Cr) intermetallic compound sheet after electrochemical treatment is taken out and ultrasonically cleaned and vacuum dried. Step 4: Vacuum heat treatment is performed on the porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum drying in Step 3 at a temperature of 200℃ for 120 min. Step 5: The porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum heat treatment in Step 4 is ultrasonically cleaned in deionized water and anhydrous ethanol for 60 min respectively, and then vacuum dried to obtain a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound with a thickness of 0.1 mm.

[0032] Example 3 like Figure 1 As shown, this embodiment includes the following steps: Step 1: β-NiAl(Cr) alloy powder with a particle size of 200-300 mesh, prepared by atomization, is loaded into a mold and pressed into shape using a press at 150 MPa. Then, it is placed into a material boat for vacuum sintering at a vacuum degree of 10. -2 Pa~10 - 3 A porous single-phase β-NiAl(Cr) intermetallic compound was obtained by sintering at 1200℃ for 2 hours, and then wire-cut to obtain a porous single-phase β-NiAl(Cr) intermetallic compound sheet with a thickness of 0.5 mm. The porous single-phase β-NiAl(Cr) intermetallic compound is a Ni-16Cr-13Al alloy with a Cr mass content of 16% and an Al mass content of 13%, and the phase is a single-phase β-NiAl(Cr). Step 2: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet from Step 1 in an acid solution of HNO3 and H2SO4, both at a concentration of 2M, for 45 min. The acid solution temperature is 40℃. Then, ultrasonically clean the sheet in deionized water, acetone, and anhydrous ethanol for 30 min in sequence. Finally, purify the sheet under a nitrogen atmosphere of 0.6 Pa to 1.0 Pa for 40 min to obtain the treated porous single-phase β-NiAl(Cr) intermetallic compound sheet. Step 3: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet treated in Step 2 as the working electrode in 4M NaOH electrolyte, with a platinum electrode as the cathode and an Ag / AgCl electrode as the reference electrode, and perform electrochemical treatment for 60 min under an applied voltage of 0.5V. Then, take out the electrochemically treated porous single-phase β-NiAl(Cr) intermetallic compound sheet and perform ultrasonic cleaning and vacuum drying. Step 4: Vacuum heat treatment is performed on the porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum drying in Step 3 at a temperature of 300℃ for 120 min. Step 5: The porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum heat treatment in Step 4 is ultrasonically cleaned in deionized water and anhydrous ethanol for 60 min respectively, and then vacuum dried to obtain a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound with a thickness of 0.5 mm.

[0033] The pore size, porosity and compressive strength of the high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compounds prepared in Examples 1 to 3 of this invention were tested, and the results are shown in Table 1 below.

[0034] Table 1

[0035] As shown in Table 1, the high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compounds prepared in Examples 1-3 of this invention have a micro-nano hierarchical pore structure, including primary pores formed by the stacking of powder particles with a size of 10μm to 25μm, and secondary pores that are uniformly distributed, have a uniform pore size, are straight-through pores, and have a size of 10nm to 100nm, with a porosity of 23% to 45%. The strength of this micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is 1468MPa to 1980M, and the phase is a single phase of β-NiAl(Cr) with a solid solution mass fraction of 16% Cr.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound, characterized in that, The method includes the following steps: Step 1: Fill β-NiAl(Cr) alloy powder into a mold, press it into shape using a press, and then perform vacuum sintering to obtain a porous single-phase β-NiAl(Cr) intermetallic compound, which is then processed into a porous single-phase β-NiAl(Cr) intermetallic compound sheet. Step 2: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet from Step 1 in an acid solution for cleaning, then ultrasonically clean it in deionized water, acetone and anhydrous ethanol in sequence, and then purify it under a nitrogen atmosphere to obtain the treated porous single-phase β-NiAl(Cr) intermetallic compound sheet. Step 3: Immerse the porous single-phase β-NiAl(Cr) intermetallic compound sheet treated in Step 2 into the electrolyte as the working electrode, with a platinum electrode as the cathode and an Ag / AgCl electrode as the reference electrode, and perform electrochemical treatment under an applied voltage. Then, take out the electrochemically treated porous single-phase β-NiAl(Cr) intermetallic compound sheet and perform ultrasonic cleaning and vacuum drying. Step 4: Perform vacuum heat treatment on the porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum drying in Step 3; Step 5: The porous single-phase β-NiAl(Cr) intermetallic compound sheet after vacuum heat treatment in Step 4 is ultrasonically cleaned in deionized water and anhydrous ethanol respectively, and then vacuum dried to obtain a high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound.

2. The method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound according to claim 1, characterized in that, The porous single-phase β-NiAl(Cr) intermetallic compound in step one is a Ni-16Cr-xAl alloy with a Cr mass content of 16% and an Al mass content of 13%~20%, and the phase is a single-phase β-NiAl(Cr).

3. The method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound according to claim 1, characterized in that, The β-NiAl(Cr) alloy powder mentioned in step one has a particle size of 100~400 mesh, the pressing pressure is 100MPa~250MPa, and the vacuum degree of the vacuum sintering is 10. -2 Pa ~10 -3 The temperature is 1100℃~1300℃, the sintering time is 2h, and the thickness of the porous single-phase β-NiAl(Cr) intermetallic compound sheet is 0.1mm~1mm.

4. The method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound according to claim 1, characterized in that, In step two, the acid in the acid solution is selected from HNO3, HCl, H2SO4 and oxalic acid. The acid solution concentration is 0.2M~2M, the acid solution temperature is 40℃~80℃, and the cleaning time in the acid solution is 15min~60min. The ultrasonic cleaning time is 60min. The pressure of the nitrogen atmosphere is 0.6Pa~1.0Pa, and the purification time is 20min~60min.

5. The method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound according to claim 1, characterized in that, The electrolyte in step three is a NaOH or KOH solution with a concentration of 1M to 4M, the applied voltage is 0.5V to 3V, and the electrochemical treatment time is 60min to 240min.

6. The method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound according to claim 1, characterized in that, The vacuum heat treatment in step four is performed at a temperature of 200℃ to 400℃ for a time of 30 min to 180 min.

7. The method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound according to claim 1, characterized in that, The ultrasonic cleaning time described in step five is 60 minutes.

8. The method for preparing a high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound according to claim 1, characterized in that, The thickness of the high-strength micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound mentioned in step five is 0.1 mm to 1 mm.

9. A high-strength micro / nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound prepared by the method according to any one of claims 1 to 8, characterized in that, It has a micro-nano hierarchical porous structure, including primary pores with a size of 10μm~25μm formed by the stacking of powder particles, and secondary pores with a uniform distribution, uniform pore size and straight through pores with a size of 10nm~100nm. The porosity is 23%~45%. The strength of this micro-nano hierarchical porous single-phase β-NiAl(Cr) intermetallic compound is 1468MPa~1980MPa. The phase is a single phase of β-NiAl(Cr) with a solid solution mass fraction of 16% Cr.

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