A method for in-situ reaction preparation of submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy by laser / electron beam

Abstract

The present invention provides a method for in-situ reaction preparation of submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy by laser / electron beam. Nb-Si elemental composite quasi-spherical powder with an atomic ratio of 5:3 is used as raw material A. At the same time, Nb in the above traditional refractory two-phase alloy SS matrix alloy is designed into Nb(X,Y,Z...) refractory high-entropy alloy (where X,Y,Z... refer to elements such as Ti,Zr,Hf,Nb,Ta,Mo,V, etc.), and it is prepared into spherical powder B by rotating electrode atomization method; then the A+B mixed powder is used as raw material for laser / electron beam additive manufacturing, so as to prepare submicron Nb5Si3 particle-reinforced Nb(X,Y,Z...) refractory high-entropy alloy, and particle-reinforced refractory high-entropy alloy is prepared by in-situ reaction during laser or electron beam selective melting process.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-high temperature composite materials and manufacturing, and in particular relates to a method for preparing a submicron Nb5Si3 particle-reinforced Nb-based refractory high entropy alloy by laser / electron beam in-situ reaction. Background Art

[0002] Composed of Nb5Si3 high temperature strengthening phase and Nb solid solution (Nb SS ) Room temperature toughening phase composition Nb5Si3 / Nb SS Refractory duplex alloys are a new generation of ultra-high temperature structural materials with a temperature tolerance of 1200-1300°C, and can be used as candidate materials for high-pressure turbine blades of future aircraft engines. SS Usually refers to solid solutions such as (Nb, Ti) ss or (Nb, Ti, Zr) ss or (Nb, Ti, Mo) ss. SS The preparation of refractory dual-phase alloys, the traditional melting and casting process will inevitably produce segregation, uneven structure, coarse grains and other problems. The size of the Nb5Si3 high temperature strengthening phase is often as high as tens of microns, which has a serious impact on the comprehensive properties of the alloy, especially the room temperature plasticity and toughness. SS Refractory duplex alloys generally have a mismatch between strength and toughness at room temperature and at low and medium temperatures, among which insufficient room temperature plasticity and toughness is the most prominent problem, coupled with insufficient high temperature strength. These seriously affect the Nb5Si3 / Nb SS Engineering applications of refractory duplex alloys.

[0003] In this field, on the one hand, how to refine Nb5Si3 / Nb SS The key problem that needs to be solved urgently is to reduce the size of the Nb5Si3 high temperature strengthening phase in the refractory dual-phase alloy to the micron or even submicron level, thereby fundamentally improving the room temperature plasticity and toughness of the alloy. SS Toughness and high temperature strength are also key issues to be solved. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing submicron Nb5Si3 particle-reinforced Nb-based refractory high entropy alloy by laser / electron beam in-situ reaction. The method of the present invention can reduce the brittleness of the particle-reinforced refractory alloy and improve the strength of the particle-reinforced refractory alloy.

[0005] The present invention provides a method for preparing a submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy by laser / electron beam in-situ reaction, comprising the following steps:

[0006] Using Nb-Si composite quasi-spherical powder and Nb-based refractory high-entropy alloy spherical powder as raw materials, in-situ reaction is carried out by laser or electron beam selective melting method to prepare sub-micron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy;

[0007] The Nb-Si composite quasi-spherical powder is obtained by solid-phase pressureless sintering of Nb powder with a particle size of 10-20 μm and Si powder with a particle size of 1-5 μm;

[0008] The Nb-based refractory high-entropy alloy is an alloy of Nb and high melting point elements, and the high melting point elements are one or several of Ti, Zr, Hf, Nb, V, Ta and Mo.

[0009] Preferably, the mass ratio of the Nb powder to the Si powder is (4-6):3.

[0010] Preferably, during the preparation of the Nb-Si composite quasi-spherical powder by solid-phase pressureless sintering, the sintering temperature is 600-1000 °C and the sintering time is 0.5-2 hours.

[0011] Preferably, after the solid-phase pressureless sintering, a plasma spheroidization treatment step is further included. During the plasma spheroidization treatment, the current is 600-800 A, the main gas flow rate is 110-130 SCFH, the auxiliary gas flow rate is 5-15 SCFH, the carrier gas flow rate is 10-15 SCFH, and the powder feeding rate is 1.5-3 r / min.

[0012] Preferably, the Nb-based refractory high-entropy alloy spherical powder is prepared by rotating electrode atomization method from the melted Nb-based alloy rod;

[0013] During the preparation by the rotating electrode atomization method, the working pressure of the inert gas in the atomization chamber is 0.115-0.135 MPa, the rotation speed is 40000-50000 r / min, the current is 700-800 A, and the feeding speed is 1.5-2 mm / s.

[0014] Preferably, in the Nb-based refractory high-entropy alloy spherical powder, the atomic percentage of any element is 5-30%.

[0015] Preferably, the in-situ reaction using laser is the in-situ reaction carried out by powder feeding laser additive manufacturing method or laser selective melting method;

[0016] In the powder feeding laser additive manufacturing, the power of the laser is 700-1000 W, the scanning speed is 600 mm / min, and the powder feeding rate is 1000 r / min;

[0017] The power of the selective laser melting is 250 - 300 W, the scanning speed is 900 - 1300 mm / s, the scanning spacing is 0.11 mm, and the layer thickness is 50 μm.

[0018] Preferably, the vacuum degree of the electron beam selective melting is 2×10 -3 ±0.5×10 -4 mbar, the working voltage is 60 kV, the electron beam power is set to 5000 - 6000 W, the powder laying thickness of each layer is 50 μm, and the preheating temperature is 300 - 700 °C.

[0019] Preferably, the mass ratio of the Nb - Si composite quasi - spherical powder to the Nb - based refractory high - entropy alloy spherical powder is (25 - 30):(70 - 75).

[0020] Preferably, after the in - situ reaction, homogenization heat treatment is carried out to obtain a sub - micron Nb5Si3 particle - reinforced Nb - based refractory high - entropy alloy;

[0021] The temperature of the homogenization heat treatment is 1350 - 1450 °C, and the time of the homogenization heat treatment is 10 - 40 hours.

[0022] The present invention provides a method for preparing a sub - micron Nb5Si3 particle - reinforced Nb - based refractory high - entropy alloy by laser / electron beam in - situ reaction, comprising the following steps: using the Nb - Si composite quasi - spherical powder and the Nb - based refractory high - entropy alloy spherical powder as raw materials, and carrying out in - situ reaction by a selective laser melting or electron beam melting method to prepare a sub - micron Nb5Si3 particle - reinforced Nb - based refractory high - entropy alloy; the Nb - Si composite quasi - spherical powder is obtained by solid - phase pressureless sintering of Nb powder with a particle size of 10 - 20 μm and Si powder with a particle size of 1 - 5 μm; the Nb - based refractory high - entropy alloy is an alloy of Nb and high - melting - point elements, and the high - melting - point elements are one or more of Ti, Zr, Hf, Nb, V, Ta, and Mo.

[0023] The present invention proposes to use Si powder raw materials with a particle size of only 1 - 5 microns and Nb powder raw materials with a particle size of 10 - 20 microns. Through scientific experiments and research, it is proved that under such conditions, a sub - micron Nb5Si3 particle - reinforced Nb5Si3 / Nb(X,Y,Z...) refractory high - entropy alloy can be obtained. Compared with the as - cast refractory alloy with the same composition, the size level of the Nb5Si3 particle - reinforced phase can be greatly reduced from the tens - of - microns level to the sub - micron level. In this way, on the one hand, the brittleness of the particle - reinforced refractory alloy is greatly reduced, and on the other hand, based on the Orowan strengthening principle, the strength of the particle - reinforced refractory alloy is also significantly improved.

[0024] In addition, the present invention designs Nb(X,Y,Z...) refractory high-entropy alloy as the alloy matrix. A super solid solution will be formed inside this multi-element refractory high-entropy alloy. Due to various strengthening and toughening mechanisms such as solid solution strengthening, lattice distortion strengthening, and precipitation strengthening, the Nb(X,Y,Z...) refractory high-entropy alloy itself has better strength and toughness and stable high-temperature strength compared to traditional binary Nb-Ti alloys, ternary alloys such as Nb-Ti-Zr or Nb-Ti-Mo. The submicron Nb5Si3 particle-reinforced Nb(X,Y,Z...) refractory high-entropy alloy material obtained by in-situ reaction additive manufacturing not only does not have defects such as cracks during the additive manufacturing process, but also the materials or parts obtained by such additive manufacturing can be directly used in the additive manufacturing state. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0026] Figure 1 SEM image of Si powder with a particle size of 1 - 5 μm in Example 1 of the present invention;

[0027] Figure 2 SEM image of Nb powder with a particle size of 10 - 20 μm in Example 1 of the present invention;

[0028] Figure 3 SEM image of quasi-spherical Nb-Si elemental composite powder obtained after plasma spheroidization in Example 1 of the present invention;

[0029] Figure 4 SEM image of spherical powder of Nb(Ti,Zr,Hf,V,Mo) refractory high-entropy alloy prepared in Example 5 of the present invention;

[0030] Figure 5 Microstructure of submicron Nb5Si3 particle-reinforced Nb5Si3 / Nb(Ti,Zr,Hf,V,Mo) refractory high-entropy alloy obtained by laser in-situ reaction in Example 5 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention provides a method for preparing submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy by laser / electron beam in-situ reaction, comprising the following steps:

[0032] Using Nb-Si composite quasi-spherical powder and Nb-based refractory high-entropy alloy spherical powder as raw materials, in-situ reaction is carried out by selective laser or electron beam melting method to prepare sub-micron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy;

[0033] The Nb-Si composite quasi-spherical powder is obtained by solid-phase pressureless sintering of Nb powder with a particle size of 10-20 μm and Si powder with a particle size of 1-5 μm;

[0034] The Nb-based refractory high-entropy alloy is an alloy of Nb and high melting point elements, and the high melting point elements are one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

[0035] In the present invention, Nb-Si elemental composite quasi-spherical powder is used as raw material A. At the same time, Nb in the above traditional refractory two-phase alloy SS The matrix alloy is designed as Nb(X,Y,Z...) refractory high-entropy alloy (where X,Y,Z... refer to elements such as Ti, Zr, Hf, Nb, Ta, Mo, V, etc.), and it is prepared into spherical powder B by rotating electrode atomization method; then the A+B mixed powder is used as raw material for laser / electron beam additive manufacturing to prepare sub-micron Nb5Si3 particle-reinforced Nb(X,Y,Z...) refractory high-entropy alloy.

[0036] Preparation of Nb-Si composite quasi-spherical powder

[0037] In the present invention, Si powder, Nb powder, PVA and water are mixed and ball-milled to obtain a slurry, and then spray granulation treatment is carried out to obtain Nb-Si composite agglomerated powder with a controllable particle size range;

[0038] Using the Nb-Si composite agglomerated powder as raw material, Nb-Si composite quasi-spherical powder is obtained by solid-phase pressureless sintering.

[0039] In the present invention, the particle size of the Si powder is preferably 1-5 μm, more preferably 2-4 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, and is preferably a range value with any of the above values as the upper or lower limit. The particle size of the Nb powder is preferably 10-20 μm, more preferably 12-18 μm, such as 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, and is preferably a range value with any of the above values as the upper or lower limit.

[0040] In the present invention, the mass ratio of the Nb powder to the Si powder is (4-6):3, preferably 5:3.

[0041] In the present invention, during the solid-phase pressureless sintering process, it is preferably carried out under an argon protection atmosphere. Sintering densification and quasi-spheroidization are carried out without melting of both elements, and the Nb-Si composite particles still remain in the state of elemental elements; the sintering temperature is preferably 600 to 1000 °C, more preferably 700 to 900 °C, such as 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, and it is preferably a range value with any of the above values as the upper or lower limit; the holding time of sintering is preferably 0.5 to 2 hours, more preferably 1 to 1.5 hours.

[0042] Preferably, in the present invention, after the Nb-Si composite quasi-spherical powder is subjected to solid-phase pressureless sintering, it is further subjected to plasma spheroidization treatment.

[0043] In the present invention, during the preparation of the Nb-Si composite quasi-spherical powder by plasma spheroidization treatment, the plasma spheroidization treatment under an argon protection atmosphere melts the surface layer of the Nb-Si composite agglomerated powder but keeps the inside in the state of Nb and Si elemental elements, and at the same time realizes the shaping and spheroidization treatment of the powder. The plasma spheroidization treatment current is preferably 600 to 800 A, more preferably 700 to 750 A, the main gas flow rate is preferably 110 - 130 SCFH, more preferably 115 to 125 SCFH, the auxiliary gas flow rate is preferably 5 to 15 SCFH, more preferably 10 to 12 SCFH, the carrier gas flow rate is preferably 10 to 15 SCFH, more preferably 12 to 13 SCFH, and the powder feeding rate is preferably 1.5 to 3 r / min, more preferably 2 to 2.5 r / min.

[0044] In principle, an in-situ reaction occurs between Nb and Si under the action of laser or electron beam heating. From a thermodynamic perspective, Nb5Si3 particles with a high melting point are preferentially formed. Moreover, this in-situ reaction results in Nb5Si3 particles with a size one order of magnitude smaller than the particle size of the original Si powder. For example, in the literature (Liu W, Xiong HP, Li N, et al. Microstructure characteristics and mechanical properties of Nb-17Si-23Ti ternary alloys fabricated by in-situ reaction laser melting deposition[J]. Acta Metallurgica Sinica(English Letters), 2018, 31: 362-370), when laser in-situ reaction is carried out using Nb particles with an average particle size of about 80 microns and Si, refractory Nb-Si particles with a micron size can be obtained, that is, the size of the Nb-Si compound particles formed by the laser in-situ reaction is one order of magnitude smaller than that of the powder raw materials used. The present invention proposes to use Si powder raw materials with a particle size of only 1-5 microns and Nb powder raw materials with a particle size of 10-20 microns. Through scientific experiments and research, it is proved that under such conditions, a Nb5Si3 / Nb(X,Y,Z...) refractory high-entropy alloy reinforced by submicron Nb5Si3 particles can be obtained. Compared with the as-cast refractory alloy with the same composition, the size of the Nb5Si3 particle reinforcement phase can be greatly reduced from the order of dozens of microns to the submicron level. In this way, on the one hand, the brittleness of the particle-reinforced refractory alloy is greatly reduced, and on the other hand, based on the Orowan strengthening principle, the strength of the particle-reinforced refractory alloy is also significantly improved.

[0045] It should be noted that if Nb5Si3 compound powder (generally with a particle size of dozens of microns) is directly prefabricated, not only does it have a high melting point and high manufacturing cost, but also in the subsequent laser additive manufacturing or electron beam selective melting deposition of the two mixed powders by mixing with Nb(X,Y,Z...), only the effect of Nb5Si3 particle distribution with a size of more than ten microns to dozens of microns can be obtained. However, if fine Nb5Si3 compound powder (such as less than ten microns) is directly prefabricated, the manufacturing cost is even higher, and it is neither suitable for powder feeding additive manufacturing alone nor for powder feeding in combination with Nb(X,Y,Z...) refractory high-entropy alloy. At the same time, the Nb5Si3 compound powder with a particle size of less than ten microns is obviously not an ideal particle size range for laser / electron beam powder bed additive manufacturing.

[0046] Preparation of Nb-based refractory high-entropy alloy spherical powder

[0047] Design Nb(X,Y,Z...) refractory high-entropy alloys to replace conventional solid-solution matrices such as (Nb,Ti)ss, (Nb,Ti,Zr)ss, or (Nb,Ti,Mo)ss, and prepare them into spherical powders by the rotating electrode atomization method.

[0048] In the present invention, during the preparation process of the rotating electrode atomization method, the working pressure of the inert gas in the atomization chamber is preferably 0.115 - 0.135 MPa, more preferably 0.120 - 0.130 MPa, the rotation speed is preferably 40000 - 50000 r / min, more preferably 42000 - 48000 r / min, most preferably 45000 - 46000 r / min, the current is preferably 700 - 800 A, more preferably 750 - 760 A, and the feeding speed is preferably 1.5 - 2 mm / s.

[0049] In the present invention, in the Nb-based refractory high-entropy alloy, the atomic percentage of any one element is preferably 5 - 30%, more preferably 10 - 25%, such as 5%, 10%, 15%, 20%, 25%, 30%, and is preferably a range value with any of the above values as the upper or lower limit.

[0050] Preparation of Submicron Nb5Si3 Particle Reinforced Nb-based Refractory High-entropy Alloy

[0051] Using the Nb-Si composite quasi-spherical powder and the Nb-based refractory high-entropy alloy spherical powder described above as raw materials, in-situ reaction is carried out by laser or electron beam selective melting method to prepare a submicron Nb5Si3 particle reinforced Nb-based refractory high-entropy alloy;

[0052] In the present invention, the mass ratio of the Nb-Si composite quasi-spherical powder to the Nb-based refractory high-entropy alloy spherical powder is preferably (25 - 30):(70 - 75), such as 25:75, 26:74, 27:73, 28:72, 29:71, 30:70, and is preferably a range value with any of the above values as the upper or lower limit.

[0053] In the present invention, the Nb-Si composite quasi-spherical powder and the Nb-based refractory high-entropy alloy spherical powder can be subjected to in-situ reaction by powder-fed laser additive manufacturing method, laser selective melting method or electron beam selective melting forming method.

[0054] In the powder-fed laser additive manufacturing, the power of the laser is preferably 700 - 1000 W, more preferably 800 - 900 W, the scanning speed is preferably 600 mm / min, and the powder feeding rate is preferably 1000 r / min;

[0055] Specifically, if single-channel powder feeding laser additive manufacturing is adopted, the Nb-Si composite quasi-spherical powder and the Nb-based refractory high-entropy alloy spherical powder need to be loaded into a powder mixer and mixed for 1 to 5 hours to obtain the A+B mixed powder for subsequent additive manufacturing. However, if dual-channel powder feeding laser additive manufacturing is adopted, the Nb-Si composite quasi-spherical powder and the Nb-based refractory high-entropy alloy spherical powder are used separately without a mixing process.

[0056] During the selective laser melting preparation process, the power is preferably 250 - 300 W, the scanning speed is preferably 900 - 1300 mm / s, more preferably 1000 - 1200 mm / s, the scanning spacing is preferably 0.11 mm, and the layer thickness is preferably 50 μm.

[0057] During the electron beam selective melting preparation process, the vacuum degree is preferably 2×10 -3 ±0.5×10 -4 mbar, more preferably 2×10 -3 ±0.3×10 -4 mbar, the working voltage is preferably 60 kV, the electron beam power is preferably set to 5000 - 6000 W, more preferably 4500 - 4600 W, the powder spreading thickness per layer is 50 μm, and the preheating temperature is preferably 300 - 700 °C, more preferably 400 - 600 °C.

[0058] After the in-situ reaction is completed, homogenization heat treatment is preferably carried out. During the homogenization heat treatment under argon protection, a small amount of Si element dissolved in the Nb(X,Y,Z...) high-entropy alloy matrix will precipitate and further react with Nb atoms in the refractory high-entropy alloy matrix to form finer nanoscale Nb5Si3 particles. Under such conditions, a Nb5Si3 / Nb(X,Y,Z...) refractory high-entropy alloy material / component with nano / submicron Nb5Si3 particle dispersion strengthening will be presented. In principle, the nano Nb5Si3 particles here will have a better strengthening effect than the submicron Nb5Si3 particles.

[0059] In the present invention, the temperature of the homogenization heat treatment is preferably 1350 - 1450 °C, more preferably 1400 °C, and the holding time of the homogenization heat treatment is preferably 10 - 40 hours, more preferably 20 - 30 hours.

[0060] The present invention provides a method for in-situ reaction of laser / electron beam to prepare a submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy, comprising the following steps: Using Nb-Si composite quasi-spherical powder and Nb-based refractory high-entropy alloy spherical powder as raw materials, in-situ reaction is carried out by laser or electron beam selective melting method to prepare a submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy; The Nb-Si composite quasi-spherical powder is obtained by solid-phase pressureless sintering of Nb powder with a particle size of 10-20 μm and Si powder with a particle size of 1-5 μm; The Nb-based refractory high-entropy alloy is an alloy of Nb and high-melting-point elements, and the high-melting-point elements are one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

[0061] The present invention proposes to use Si powder raw materials with a particle size of only 1-5 microns and Nb powder raw materials with a particle size of 10-20 microns. Through scientific experiments and research, it is proved that under such conditions, a submicron Nb5Si3 particle-reinforced Nb5Si3 / Nb(X,Y,Z...) refractory high-entropy alloy can be obtained. Compared with the as-cast refractory alloy of the same composition, the size level of the Nb5Si3 particle reinforcement phase can be greatly reduced from dozens of microns to the submicron level. In this way, on the one hand, the brittleness of the particle-reinforced refractory alloy is greatly reduced, and on the other hand, based on the Orowan strengthening principle, the strength of the particle-reinforced refractory alloy will also be significantly improved.

[0062] In addition, the present invention designs Nb(X,Y,Z...) refractory high-entropy alloy as the alloy matrix. A super solid solution will be formed inside this multi-element refractory high-entropy alloy. Due to various strengthening and toughening mechanisms such as solid solution strengthening, lattice distortion strengthening, and precipitation strengthening, the Nb(X,Y,Z...) refractory high-entropy alloy itself has better strength and toughness and stable high-temperature strength compared with traditional Nb-Ti binary alloys, Nb-Ti-Zr or Nb-Ti-Mo ternary alloys. The submicron Nb5Si3 particle-reinforced Nb(X,Y,Z...) refractory high-entropy alloy material obtained by in-situ reaction additive manufacturing not only does not have defects such as cracks during the additive manufacturing process, but also the materials or parts obtained by such additive manufacturing can be directly used in the additive manufacturing state.

[0063] In order to further illustrate the present invention, the following takes examples to describe in detail a method for in-situ reaction of laser / electron beam to prepare a submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy provided by the present invention, but it should not be construed as a limitation to the protection scope of the present invention.

[0064] Example 1 Preparation of Nb-Si Composite Powder A

[0065] Select Si powder with a raw material particle size of 1 - 5 microns and Nb powder with a raw material particle size of 10 - 20 microns, and mix them according to an atomic ratio of 5:3; then prepare the slurry: weigh Nb powder, Si powder, PVA, and deionized water in sequence according to the mass ratio, place them in a ball milling tank, and then fix the ball milling tank on a planetary ball mill to ball mill to obtain the required slurry; then perform spray granulation treatment to obtain Nb-Si elemental composite agglomerated powder with a controllable particle size range.

[0066] Next, for the above-mentioned Nb-Si elemental composite agglomerated powder, process it in the following manner to obtain quasi-spherical Nb-Si composite powder A: powder solid-phase pressureless sintering under a high-purity argon protective atmosphere, perform sintering densification and quasi-spheroidization without melting the two elemental powders, and the Nb-Si composite particles still remain in the elemental state. The typical parameters of the solid-phase pressureless sintering are: sintering temperature 800 °C, sintering time 1 hour, and then perform plasma spheroidization treatment under an argon protective atmosphere to melt the surface layer of the Nb-Si composite agglomerated powder and achieve powder shaping and spheroidization treatment. The typical parameters of the plasma spheroidization process are: current 700 A, main gas 130 SCFH, auxiliary gas 10 SCFH, carrier gas 11 SCFH, powder feeding rate 2.0 r / min.

[0067] Example 2 Preparation of Nb(X,Y,Z...) refractory high-entropy alloy powder B

[0068] Design Nb(X,Y,Z...) refractory high-entropy alloy to replace conventional solid solution matrices such as (Nb,Ti)ss or (Nb,Ti,Zr)ss or (Nb,Ti,Mo)ss, etc. The atomic percentages of each element in the above Nb(X,Y,Z...) refractory high-entropy alloy are between 5% - 30%, and use the rotating electrode atomization method to prepare the melted alloy rod into spherical powder B. High-purity argon is used as the working medium in the process of the rotating electrode atomization method. The working pressure of the inert gas in the atomization chamber is 0.115 MPa, the rotation speed is 40000 r / min, the current is 750 A, and the feeding speed is 2 mm / s.

[0069] Mix powder A in Example 1 and powder B in Example 2 according to a mass ratio of 27:73 as the raw materials in the following Examples 3 - 6.

[0070] Example 3 Single-channel powder feeding type laser additive manufacturing

[0071] (1) The refractory high-entropy alloy system is Nb35-Ti15-Zr20-Hf15-V15, and establish a three-dimensional CAD model of a refractory alloy rectangular test block with a size of 15×15×10 mm 3 to be prepared, and fill the scanning path for each layer slice.

[0072] (2) Using the A+B mixed powder as the raw material, through the single-channel powder feeding laser additive manufacturing method, the in-situ reaction between Nb and Si in the molten state and the rapid solidification process, a submicron Nb5Si3 particle-reinforced Nb5Si3 / Nb(Ti,Zr,Hf,V) refractory high-entropy alloy material or part is prepared. The typical parameters of powder feeding laser additive manufacturing are a laser power of 800 W, a scanning speed of 600 mm / min, and a powder feeding rate of 1000 r / min.

[0073] (3) The powder feeding laser additive manufacturing forming system starts to form. The powder is sent out and melted and solidified according to the path generated by the computer, and then layer by layer accumulation is carried out until the alloy specimen or part is completely prepared.

[0074] The effect obtained in this example is that through the combined detection and analysis of SEM and TEM, in the obtained alloy specimen or part, the size of the Nb5Si3 particles in the microstructure is 200 - 600 nm submicron, and these Nb5Si3 particles are dispersedly distributed.

[0075] Example 4 Dual-channel powder feeding laser additive manufacturing

[0076] (1) The refractory high-entropy alloy system is Nb35-Ti15-Zr20-Hf15-V15. A three-dimensional CAD model of a rectangular refractory alloy test block with dimensions of 15×15×10 mm to be prepared is established, and the scanning path filling is carried out for each layer of slices. 3

[0077] (2) The A powder and B powder are subjected to laser additive manufacturing through dual-channel powder feeding. Through the in-situ reaction between Nb and Si in the molten state and the rapid solidification process, a submicron Nb5Si3 particle-reinforced Nb5Si3 / Nb(Ti,Zr,Hf,V) refractory high-entropy alloy material or part is prepared. The typical parameters of powder feeding laser additive manufacturing are a laser power of 800 W, a scanning speed of 600 mm / min, and a powder feeding rate of 1000 r / min.

[0078] (3) The powder feeding laser additive manufacturing forming system starts to form. The powder is sent out and melted and solidified according to the path generated by the computer, and then layer by layer accumulation is carried out until the alloy specimen or part is completely prepared.

[0079] The effect obtained in this example is that through the combined detection and analysis of SEM and TEM, in the obtained alloy specimen or part, the size of the Nb5Si3 particles in the microstructure is 200 - 600 nm submicron, and these Nb5Si3 particles are dispersedly distributed.

[0080] Example 5 Selective laser melting forming

[0081] (1) The refractory high-entropy alloy system is Nb30-Ti15-Zr15-Hf15-V15-Mo10, and a 15×15×10 mm 3 The STL file is exported from the model, and the Magics software dedicated to model processing is used to repair and place the parts of the model;

[0082] (2) The slice file is exported, and the EP Hatch software is used to set process parameters for the parts and the furnace sample: power 300 W, scanning speed 1200 mm / s, scanning spacing 0.11 mm, layer thickness 50 μm.

[0083] (3) The A+B mixed metal powder is added to the equipment hopper. After preheating the substrate, leveling, and powder spreading, the chamber door is closed, argon is turned on, the inlet pressure is 0.5 MPa, the ventilation cycle, water cooling, scanning galvanometer, and laser are turned on. After the oxygen content reaches the set value of less than 1000 ppm, the forming starts. Through the powder bed fusion laser additive manufacturing method, the in-situ reaction between Nb and Si in the molten state and the rapid solidification process are used to prepare a submicron Nb5Si3 particle-reinforced Nb5Si3 / Nb(Ti,Zr,Hf,V,Mo) refractory high-entropy alloy material or part. After processing is completed, the material or part is taken out.

[0084] The effect obtained in this example is that through the combined detection and analysis of SEM and TEM, in the obtained alloy sample or part, the size of the Nb5Si3 particles in the obtained microstructure is 300-700 nm, and these Nb5Si3 particles are dispersedly distributed.

[0085] Example 6 Electron beam selective melting forming

[0086] (1) The refractory high-entropy alloy system is Nb25-Ti13-Zr12-Hf15-V15-Mo10-Ta10, and a three-dimensional CAD model of a rectangular refractory alloy test block with a size of 15×15×70 mm to be prepared is established. Then, it is sliced in the direction of 70 mm in height, and the scanning path of each layer of slice is filled. Then, the slice information and the scanning path information are imported into the electron beam selective melting forming system. 3 (2) First, the powder bed is preheated with a defocused electron beam, and the preheating temperature is adjustable at 600 °C to slightly consolidate the alloy powder.

[0087] (3) Then, each layer of powder is heated, melted, and solidified along the path generated by the computer, and then accumulated layer by layer until the alloy sample is prepared. The electron beam selective melting forming parameters are: the forming vacuum degree is maintained at 2×10

[0088] (3) Then, each layer of powder is heated, melted, and solidified along the path generated by the computer, and then accumulated layer by layer until the alloy sample is prepared. The electron beam selective melting forming parameters are: the forming vacuum degree is maintained at 2×10 -3 ±0.5×10- 4 mbar, with a working voltage of 60 kV, an electron beam power of 500 W, and a powder laying thickness of 50 μm per layer. In this way, through the powder laying type electron beam additive manufacturing method, a Nb5Si3 / Nb(Ti,Zr,Hf,Nb,Mo,Ta) refractory high entropy alloy material or workpiece reinforced by submicron Nb5Si3 particles was prepared and obtained.

[0089] The effect obtained in this example is that through SEM detection and analysis, in the obtained alloy specimen or workpiece, the size of the Nb5Si3 particles in the obtained microstructure is 150 - 500 nm, and these Nb5Si3 particles are dispersedly distributed.

[0090] Finally, for the refractory high entropy alloy materials / workpieces prepared in the above Examples 3 - 6, homogenization heat treatment is carried out under argon protection at 1400 ± 50 °C for 10 - 40 hours. A small amount of Si dissolved in the Nb(X,Y,Z...) high entropy alloy matrix will precipitate and react with Nb atoms in the matrix alloy, and this part will generate finer nanoscale Nb5Si3 particles. In this way, in the refractory high entropy alloy material / workpiece, a Nb5Si3 / Nb(X,Y,Z...) refractory high entropy alloy material / workpiece with nano / submicron Nb5Si3 particle dispersion strengthening will be presented, where the nano Nb5Si3 particles will have a better strengthening effect than the submicron Nb5Si3 particles.

[0091] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for in-situ reaction of laser / electron beam to prepare submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy, comprising the following steps: Using Nb-Si composite quasi-spherical powder and Nb-based refractory high-entropy alloy spherical powder as raw materials, and carrying out in-situ reaction by laser or electron beam selective melting method to prepare submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy; The Nb-Si composite quasi-spherical powder is obtained by solid-phase pressureless sintering of Nb powder with a particle size of 10-20 μm and Si powder with a particle size of 1-5 μm; The Nb-based refractory high-entropy alloy is an alloy of Nb and high melting point elements, and the high melting point elements are one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

2. The method according to claim 1, wherein The mass ratio of the Nb powder to the Si powder is (4-6):

3.

3. The method according to claim 1, characterized in that, During the preparation of the Nb-Si composite quasi-spherical powder by solid-phase pressureless sintering, the sintering temperature is 600-1000 °C and the sintering time is 0.5-2 hours.

4. The method according to claim 1, wherein After the solid-phase pressureless sintering, it further includes a plasma spheroidization treatment step. During the plasma spheroidization treatment, the current is 600-800 A, the main gas flow rate is 110-130 SCFH, the auxiliary gas flow rate is 5-15 SCFH, the carrier gas flow rate is 10-15 SCFH, and the powder feeding rate is 1.5-3 r / min.

5. The method according to claim 1, wherein The Nb-based refractory high-entropy alloy spherical powder is prepared by melting the Nb-based alloy rod through the rotating electrode atomization method; During the preparation by the rotating electrode atomization method, the working pressure of the inert gas in the atomization chamber is 0.115-0.135 MPa, the rotation speed is 40000-50000 r / min, the current is 700-800 A, and the feeding speed is 1.5-2 mm / s.

6. The method according to claim 5, characterized in that, In the Nb-based refractory high-entropy alloy spherical powder, the atomic percentage of any element is 5-30%.

7. The method according to claim 1, wherein The in-situ reaction using laser is carried out by the powder feeding type laser additive manufacturing method for in-situ reaction or the laser selective melting method for in-situ reaction; In the powder feeding type laser additive manufacturing, the power of the laser is 700-1000 W, the scanning speed is 600 mm / min, and the powder feeding rate is 1000 r / min; The power of the laser selective melting is 250-300 W, the scanning speed is 900-1300 mm / s, the scanning spacing is 0.11 mm, and the layer thickness is 50 μm.

8. The method according to claim 1, wherein The vacuum degree of the electron beam selective melting is 2×10 -3 ±0.5×10 -4 mbar, the working voltage is 60 kV, the electron beam power is set to 5000 - 6000 W, the powder laying thickness per layer is 50 μm, and the preheating temperature is 300 - 700 °C.

9. The method according to claim 1, characterized in that, The mass ratio of the Nb-Si composite quasi-spherical powder to the Nb-based refractory high-entropy alloy spherical powder is (25-30):(70-75).

10. The method according to any one of claims 1 to 9, characterized in that After the in-situ reaction, homogenization heat treatment is carried out to obtain nano / submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy; The temperature of the homogenization heat treatment is 1350-1450 °C, and the time of the homogenization heat treatment is 10-40 hours.

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