Method for preparing submicron nb 5si 3 particle-reinforced nb-based refractory high-entropy alloy by laser / electron beam in-situ reaction

Abstract

Provided is a method for preparing a submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy by a laser / electron beam in-situ reaction. Quasi-spherical composite powder of elemental Nb-Si with an atomic ratio of 5:3 is used as a raw material A, and an NbSS matrix alloy in the traditional refractory two-phase alloy is designed into an Nb(X, Y, Z ...) refractory high-entropy alloy (wherein X, Y, Z … means elements such as Ti, Zr, Hf, Nb, Ta, Mo, and V), which is prepared into spherical powder B by means of a rotating electrode atomization method; and then the A+B mixed powder is used as a raw material for laser / electron beam additive manufacturing, so that a submicron Nb5Si3 particle-reinforced Nb(X, Y, Z ...) refractory high-entropy alloy is prepared, and thus the particle-reinforced refractory high-entropy alloy is prepared by means of an in-situ reaction in a laser or electron beam selective melting process.

Description

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

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on December 6, 2023, with application number 202311669663.8 and invention name “A method for preparing submicron Nb5Si3 particle reinforced Nb-based refractory high-entropy alloy by laser / electron beam in-situ reaction”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the field of ultra-high temperature composite materials and manufacturing technology, 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

[0003] 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 target of 1200-1300℃, 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, and the size of the Nb5Si3 high temperature strengthening phase is often as high as tens of microns, which will seriously damage 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, with insufficient room temperature plasticity and toughness being the most prominent problem, coupled with insufficient high temperature strength. These factors seriously affect the performance of Nb5Si3 / Nb SS Engineering applications of refractory duplex alloys.

[0004] 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

[0005] The object of the present invention is to provide a method for preparing submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloys by laser / electron beam in-situ reaction. The method of the present invention can reduce the brittleness of the particle-reinforced refractory alloys and improve the strength of the particle-reinforced refractory alloys.

[0006] 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:

[0007] Using Nb-Si composite quasi-spherical powder and Nb-based refractory high entropy alloy spherical powder as raw materials, submicron Nb5Si3 particle-reinforced Nb-based refractory high entropy alloy is prepared by in-situ reaction through laser or electron beam selective melting method.

[0008] The Nb-Si composite quasi-spherical powder is obtained by solid phase pressureless sintering of Nb powder with a particle size of 10 to 20 μm and Si powder with a particle size of 1 to 5 μm.

[0009] The Nb-based refractory high-entropy alloy is an alloy of Nb and a high-melting-point element, and the high-melting-point element is one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

[0010] Preferably, the mass ratio of the Nb powder to the Si powder is (4-6):3.

[0011] Preferably, in the process of preparing 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.

[0012] Preferably, after the solid phase pressureless sintering, a plasma spheroidization treatment step is also included. During the plasma spheroidization treatment, the current is 600-800A, the main gas flow rate is 110-130SCFH, the auxiliary gas flow rate is 5-15SCFH, the carrier gas flow rate is 10-15SCFH, and the powder feeding rate is 1.5-3r / min.

[0013] Preferably, the Nb-based refractory high entropy alloy spherical powder is prepared from the melted Nb-based alloy rod by a rotating electrode atomization method;

[0014] During the rotary electrode atomization preparation process, the working pressure of the inert gas in the atomization chamber is 0.115-0.135 MPa, the rotation speed is 40,000-50,000 r / min, the current is 700-800 A, and the feed speed is 1.5-2 mm / s.

[0015] Preferably, the atomic percentage of any element in the Nb-based refractory high entropy alloy spherical powder is 5 to 30%.

[0016] Preferably, the in-situ reaction using laser is an in-situ reaction using a powder feeding laser additive manufacturing method or a laser selective melting method;

[0017] In the powder feeding laser additive manufacturing, the laser power is 700-1000W, the scanning speed is 600mm / min, and the powder feeding rate is 1000r / min;

[0018] The power of the laser selective melting is 250-300W, the scanning speed is 900-1300 mm / s, the scanning interval is 0.11 mm, and the layer thickness is 50 μm.

[0019] Preferably, the vacuum degree of the electron beam selective melting is 2×10 -3 ±0.5×10 -4 mbar, the working voltage is 60kV, the electron beam power is set to 5000~6000W, the thickness of each layer of powder is 50μm, and the preheating temperature is 300~700℃.

[0020] 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).

[0021] Preferably, after the in-situ reaction, a homogenization heat treatment is performed to obtain a submicron Nb5Si3 particle reinforced Nb-based refractory high entropy alloy;

[0022] The temperature of the homogenization heat treatment is 1350-1450° C., and the time of the homogenization heat treatment is 10-40 hours.

[0023] 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. The method comprises the following steps: using Nb-Si composite quasi-spherical powder and Nb-based refractory high-entropy alloy spherical powder as raw materials, carrying out in-situ reaction by a 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 to 20 μm and Si powder with a particle size of 1 to 5 μm; the Nb-based refractory high-entropy alloy is an alloy of Nb and a high-melting-point element, and the high-melting-point element is one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

[0024] This invention proposes using Si powder with a particle size of only 1-5 microns and Nb powder with a particle size of 10-20 microns. Through scientific experiments and research, it has been demonstrated that under these conditions, a Nb5Si3 / Nb(X,Y,Z...) refractory high-entropy alloy reinforced with submicron Nb5Si3 particles can be obtained. Compared to a cast refractory alloy of the same composition, the size of the Nb5Si3 particles can be significantly reduced from tens of microns to submicron levels. This significantly reduces the brittleness of the particle-reinforced refractory alloy and, based on the Orowan strengthening principle, significantly improves its strength.

[0025] Furthermore, the present invention employs a Nb(X,Y,Z...) refractory high-entropy alloy as the alloy matrix. This multi-component refractory high-entropy alloy forms a supersolid solution within it. Due to various strengthening mechanisms, including solid solution strengthening, lattice distortion strengthening, and precipitation strengthening, the Nb(X,Y,Z...) refractory high-entropy alloy exhibits superior toughness and stable high-temperature strength compared to conventional binary Nb-Ti alloys, Nb-Ti-Zr, or Nb-Ti-Mo ternary alloys. The Nb(X,Y,Z...) refractory high-entropy alloy material reinforced with submicron Nb5Si3 particles, obtained by in-situ reactive additive manufacturing, not only avoids defects such as cracking during the additive manufacturing process, but also allows for direct use of the resulting material or component in the additively manufactured state. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0027] FIG1 is a SEM image of Si powder with a particle size of 1 to 5 μm in Example 1 of the present invention;

[0028] FIG2 is a SEM image of Nb powder with a particle size of 10 to 20 μm in Example 1 of the present invention;

[0029] FIG3 is a SEM image of the quasi-spherical Nb-Si single element composite powder obtained after plasma spheroidization in Example 1 of the present invention;

[0030] FIG4 is a SEM image of the Nb (Ti, Zr, Hf, V, Mo) refractory high entropy alloy spherical powder prepared in Example 5 of the present invention;

[0031] Figure 5 shows the microstructure of the 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

[0032] 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:

[0033] Using Nb-Si composite quasi-spherical powder and Nb-based refractory high entropy alloy spherical powder as raw materials, submicron Nb5Si3 particle-reinforced Nb-based refractory high entropy alloy is prepared by in-situ reaction through laser or electron beam selective melting method.

[0034] The Nb-Si composite quasi-spherical powder is obtained by solid phase pressureless sintering of Nb powder with a particle size of 10 to 20 μm and Si powder with a particle size of 1 to 5 μm.

[0035] The Nb-based refractory high-entropy alloy is an alloy of Nb and a high-melting-point element, and the high-melting-point element is one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

[0036] In the present invention, Nb-Si single element composite quasi-spherical powder is used as raw material A, and at the same time, Nb in the above-mentioned traditional refractory dual-phase alloy is SS The matrix alloy is designed to be a Nb(X,Y,Z...) refractory high-entropy alloy (where X,Y,Z... refers to elements such as Ti, Zr, Hf, Nb, Ta, Mo, and V), and is prepared into a spherical powder B by a rotating electrode atomization method. The A+B mixed powder is then used as a raw material for laser / electron beam additive manufacturing to prepare a submicron Nb5Si3 particle-reinforced Nb(X,Y,Z...) refractory high-entropy alloy.

[0037] Preparation of Nb-Si composite quasi-spherical powder

[0038] The present invention mixes Si powder, Nb powder, PVA and water, performs ball milling to obtain a slurry, and then performs spray granulation treatment to obtain Nb-Si composite agglomerated powder with a controllable particle size range;

[0039] Nb-Si composite quasi-spherical powders were obtained by solid phase pressureless sintering using Nb-Si composite agglomerated powders as raw materials.

[0040] In the present invention, the particle size of the Si powder is preferably 1 to 5 μm, more preferably 2 to 4 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, and 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 to 20 μm, more preferably 12 to 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 preferably a range value with any of the above values ​​as the upper or lower limit.

[0041] In the present invention, the mass ratio of the Nb powder to the Si powder is (4-6):3, preferably 5:3.

[0042] In the present invention, during the solid-phase pressureless sintering process, sintering is preferably carried out under an argon protective atmosphere, and sintering densification and quasi-spheroidization are carried out without melting both elements, and the Nb-Si composite particles still maintain a single element state; the sintering temperature is preferably 600-1000°C, more preferably 700-900°C, such as 600°C, 700°C, 800°C, 900°C, 1000°C, preferably a range value with any of the above values ​​as the upper or lower limit; the sintering holding time is preferably 0.5-2 hours, more preferably 1-1.5 hours.

[0043] Preferably, in the present invention, the Nb-Si composite quasi-spherical powder is subjected to plasma spheroidization treatment after solid phase pressureless sintering.

[0044] In the present invention, in the process of preparing Nb-Si composite quasi-spherical powder by plasma spheroidization, the plasma spheroidization treatment under an argon protective atmosphere causes the surface layer of the Nb-Si composite agglomerated powder to melt while the interior remains in the state of Nb and Si elemental elements, while simultaneously achieving powder shaping and spheroidization. The plasma spheroidization treatment current is preferably 600-800A, more preferably 700-750A, the main gas flow rate is preferably 110-130SCFH, more preferably 115-125SCFH, the auxiliary gas flow rate is preferably 5-15SCFH, more preferably 10-12SCFH, the carrier gas flow rate is preferably 10-15SCFH, more preferably 12-13SCFH, and the powder feeding rate is preferably 1.5-3r / min, more preferably 2-2.5r / min.

[0045] In principle, an in-situ reaction between Nb and Si occurs under laser or electron beam heating, which thermodynamically prioritizes the production of high-melting-point Nb5Si3 particles. Furthermore, this in-situ reaction results in Nb5Si3 particles having a size one order of magnitude smaller than 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), Nb particles with an average particle size of approximately 80 μm and Si were used for an in-situ laser reaction to obtain micron-sized refractory Nb-Si particles. This indicates that the particle size of the Nb-Si compound produced by the in-situ laser reaction is one order of magnitude smaller than that of the powdered raw material used. This invention proposes using Si powder with a particle size of only 1-5 microns and Nb powder with a particle size of 10-20 microns. Through scientific experiments and research, it has been demonstrated that under these conditions, a Nb5Si3 / Nb(X,Y,Z...) refractory high-entropy alloy reinforced with submicron Nb5Si3 particles can be obtained. Compared to a cast refractory alloy of the same composition, the size of the Nb5Si3 particles can be significantly reduced from tens of microns to submicron levels. This significantly reduces the brittleness of the particle-reinforced refractory alloy and, based on the Orowan strengthening principle, significantly improves its strength.

[0046] It should be pointed out that if Nb5Si3 compound powder (generally with a particle size of tens of microns) is directly prefabricated, not only will its melting point and manufacturing cost be high, but the subsequent mixing with Nb(X,Y,Z...) for laser additive manufacturing or electron beam selective melting deposition of the two mixed powders will only produce Nb5Si3 particle distribution effects ranging from tens to tens of microns in size. However, if fine Nb5Si3 compound powder (for example, less than ten microns) is directly prefabricated, the manufacturing cost will be even higher, and it is not suitable for powder feeding additive manufacturing alone, nor is it suitable for mixing powder feeding with Nb(X,Y,Z...) refractory high-entropy alloys. At the same time, Nb5Si3 compound powders below ten microns are obviously not in the ideal particle size range for laser / electron beam powder spreading additive manufacturing.

[0047] Preparation of Spherical Powders of Nb-Based Refractory High Entropy Alloy

[0048] Nb(X,Y,Z...) refractory high entropy alloy is designed to replace conventional solid solution matrices such as (Nb,Ti)ss or (Nb,Ti,Zr)ss or (Nb,Ti,Mo)ss, and is prepared into spherical powder by rotating electrode atomization.

[0049] In the present invention, during the rotary electrode atomization preparation process, 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 feed speed is preferably 1.5-2 mm / s.

[0050] In the present invention, the atomic percentage of any one element in the Nb-based refractory high-entropy alloy is preferably 5 to 30%, more preferably 10 to 25%, such as 5%, 10%, 15%, 20%, 25%, 30%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0051] Preparation of Submicron Nb5Si3 Particle-Reinforced Nb-Based Refractory High Entropy Alloys

[0052] Using the above-mentioned Nb-Si composite quasi-spherical powder and Nb-based refractory high-entropy alloy spherical powder as raw materials, a submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy is prepared by in-situ reaction through laser or electron beam selective melting method;

[0053] In the present invention, the mass ratio of the Nb-Si composite quasi-spherical powder and 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, preferably a range value with any of the above values ​​as the upper or lower limit.

[0054] In the present invention, a powder laser additive manufacturing method, a laser selective melting method or an electron beam selective melting forming method can be used to make the Nb-Si composite quasi-spherical powder and the Nb-based refractory high entropy alloy spherical powder react in situ.

[0055] In the powder feeding laser additive manufacturing, the laser power is preferably 700-1000W, more preferably 800-900W, the scanning speed is preferably 600mm / min, and the powder feeding rate is preferably 1000r / min;

[0056] Specifically, if single-channel powder feeding laser additive manufacturing is used, the Nb-Si composite quasi-spherical powder and the Nb-based refractory high-entropy alloy spherical powder must first 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 used, the Nb-Si composite quasi-spherical powder and the Nb-based refractory high-entropy alloy spherical powder are used separately, eliminating the need for a mixing step.

[0057] During the selective laser melting 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.

[0058] During the electron beam selective melting 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 60kV, the electron beam power is preferably set to 5000-6000W, more preferably 4500-4600W, the thickness of each layer of powder is 50μm, and the preheating temperature is preferably 300-700℃, more preferably 400-600℃.

[0059] After the in-situ reaction is completed, it is preferably to carry out homogenization heat treatment. 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 out and further react with the Nb atoms in the refractory high entropy alloy matrix to generate even finer nano-scale Nb5Si3 particles. Under this condition, the Nb5Si3 / Nb(X,Y,Z...) refractory high entropy alloy material / parts with enhanced dispersion of nano / submicron Nb5Si3 particles will appear. In principle, the nano Nb5Si3 particles here will have a better strengthening effect than the submicron Nb5Si3 particles.

[0060] 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.

[0061] 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. The method comprises the following steps: using Nb-Si composite quasi-spherical powder and Nb-based refractory high-entropy alloy spherical powder as raw materials, carrying out in-situ reaction by a 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 to 20 μm and Si powder with a particle size of 1 to 5 μm; the Nb-based refractory high-entropy alloy is an alloy of Nb and a high-melting-point element, and the high-melting-point element is one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

[0062] This invention proposes using Si powder with a particle size of only 1-5 microns and Nb powder with a particle size of 10-20 microns. Through scientific experiments and research, it has been demonstrated that under these conditions, a Nb5Si3 / Nb(X,Y,Z...) refractory high-entropy alloy reinforced with submicron Nb5Si3 particles can be obtained. Compared to a cast refractory alloy of the same composition, the size of the Nb5Si3 particles can be significantly reduced from tens of microns to submicron levels. This significantly reduces the brittleness of the particle-reinforced refractory alloy and, based on the Orowan strengthening principle, significantly improves its strength.

[0063] Furthermore, the present invention employs a Nb(X,Y,Z...) refractory high-entropy alloy as the alloy matrix. This multi-component refractory high-entropy alloy forms a supersolid solution within it. Due to various strengthening mechanisms, including solid solution strengthening, lattice distortion strengthening, and precipitation strengthening, the Nb(X,Y,Z...) refractory high-entropy alloy exhibits superior toughness and stable high-temperature strength compared to conventional binary Nb-Ti alloys, Nb-Ti-Zr, or Nb-Ti-Mo ternary alloys. The Nb(X,Y,Z...) refractory high-entropy alloy material reinforced with submicron Nb5Si3 particles, obtained by in-situ reactive additive manufacturing, not only avoids defects such as cracking during the additive manufacturing process, but also allows for direct use of the resulting material or component in the additively manufactured state.

[0064] To further illustrate the present invention, the following detailed description of a method for preparing submicron Nb5Si3 particle-reinforced Nb-based refractory high-entropy alloy by laser / electron beam in-situ reaction provided by the present invention is provided in conjunction with examples. However, this should not be construed as limiting the scope of protection of the present invention.

[0065] Example 1 Preparation of Nb-Si composite powder A

[0066] 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 are selected and mixed according to an atomic ratio of 5:3; then a slurry is prepared: Nb powder, Si powder, PVA, and deionized water are weighed in order according to the mass ratio, placed in a ball mill, and then the ball mill is fixed on a planetary ball mill to obtain the required slurry; then a spray granulation treatment is performed to obtain a Nb-Si single element composite agglomerated powder with a controllable particle size range.

[0067] Next, the above-mentioned Nb-Si single element composite agglomerated powder is processed as follows to obtain quasi-spherical Nb-Si composite powder A: the powder is solid-phase pressureless sintered under a high-purity argon protective atmosphere, and sintering densification and quasi-spheroidization are performed without melting the two element powders, and the Nb-Si composite particles still maintain the single element state. The typical parameters of solid-phase pressureless sintering are: sintering temperature 800°C, sintering time 1 hour, and then plasma spheroidization treatment is performed under an argon protective atmosphere to melt the surface layer of the Nb-Si composite agglomerated powder and realize the shaping and spheroidization of the powder. The typical parameters of the plasma spheroidization process are: current 700A, main gas 130SCFH, auxiliary gas 10SCFH, carrier gas 11SCFH, and powder feeding rate 2.0r / min.

[0068] Example 2 Preparation of Nb(X,Y,Z...) Refractory High Entropy Alloy Powder B

[0069] A Nb(X,Y,Z...) refractory high-entropy alloy was designed to replace a conventional solid solution matrix such as (Nb,Ti)ss, (Nb,Ti,Zr)ss, or (Nb,Ti,Mo)ss. The atomic percentages of the individual elements in the Nb(X,Y,Z...) refractory high-entropy alloy ranged from 5% to 30%. Spherical powder B was then prepared from the melted alloy rods using a rotary electrode atomization method. High-purity argon was used as the working medium in the rotary electrode atomization process. The inert gas pressure within the atomization chamber was 0.115 MPa, the rotation speed was 40,000 r / min, the current was 750 A, and the feed rate was 2 mm / s.

[0070] Powder A in Example 1 and powder B in Example 2 were mixed in a mass ratio of 27:73 and used as raw materials in the following Examples 3 to 6.

[0071] Example 3 Single-channel powder feeding laser additive manufacturing

[0072] (1) The refractory high entropy alloy system is Nb35-Ti15-Zr20-Hf15-V15, and the construction size is 15×15×10mm 3 A three-dimensional CAD model of a rectangular test block of refractory alloy to be prepared is prepared, and the scanning path of each slice is filled.

[0073] (2) Using the A+B mixed powder as raw material, a single-channel powder feeding laser additive manufacturing method is used to produce Nb5Si3 / Nb(Ti, Zr, Hf, V) refractory high-entropy alloy materials or parts reinforced with submicron Nb5Si3 particles through an in-situ reaction between Nb and Si in the molten state and a rapid solidification process. Typical parameters for powder feeding laser additive manufacturing are laser power 800W, scanning speed 600mm / min, and powder feeding rate 1000r / min.

[0074] (3) The powder feeding laser additive manufacturing forming system starts forming, feeding the powder and melting and solidifying it according to the path generated by the computer, and then accumulating it layer by layer until the alloy sample or part is completed.

[0075] The effect obtained in this embodiment is that, through joint detection and analysis by SEM and TEM, in the obtained alloy sample or workpiece, the submicron size of Nb5Si3 particles in the obtained microstructure is 200-600nm, and these Nb5Si3 particles are dispersed.

[0076] Example 4 Dual-channel powder feeding laser additive manufacturing

[0077] (1) The refractory high entropy alloy system is Nb35-Ti15-Zr20-Hf15-V15, and the construction size is 15×15×10mm 3 A three-dimensional CAD model of a rectangular test block of refractory alloy to be prepared is prepared, and the scanning path of each slice is filled.

[0078] (2) Powders A and B are fed through a dual-channel laser additive manufacturing process. The in-situ reaction between Nb and Si in the molten state and the rapid solidification process produce submicron Nb5Si3 particle-reinforced Nb5Si3 / Nb(Ti,Zr,Hf,V) refractory high-entropy alloy materials or parts. Typical parameters for powder-feeding laser additive manufacturing are laser power 800W, scanning speed 600mm / min, and powder feeding rate 1000r / min.

[0079] (3) The powder feeding laser additive manufacturing forming system starts forming, feeding the powder and melting and solidifying it according to the path generated by the computer, and then accumulating it layer by layer until the alloy sample or part is completed.

[0080] The effect obtained in this embodiment is that, through joint detection and analysis by SEM and TEM, in the alloy sample or workpiece obtained, the submicron size of Nb5Si3 particles in the microstructure is 200-600nm, and these Nb5Si3 particles are dispersed.

[0081] Example 5 Laser Selective Melting Forming

[0082] (1) The refractory high entropy alloy system is Nb30-Ti15-Zr15-Hf15-V15-Mo10, and the 15×15×10mm 3 Export the model to STL file and use Magics software, a special software for model processing, to repair and arrange the parts;

[0083] (2) Export the slice file and use EP Hatch software to set the process parameters for the parts and furnace samples: power 300W, scanning speed 1200mm / s, scanning spacing 0.11mm, and layer thickness 50μm.

[0084] (3) Add the A+B mixed metal powder to the equipment hopper. After preheating, leveling, and spreading the powder on the substrate, close the hatch, turn on the argon gas, and set the air inlet pressure to 0.5 MPa. Turn on the ventilation cycle, water cooling, scanning galvanometer, and laser. After the oxygen content reaches the set value below 1000 ppm, start forming. Through the powder-spreading 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, Mo) refractory high-entropy alloy material or part is obtained. After processing is completed, the material or part is removed.

[0085] The effect obtained in this embodiment is that, through joint detection and analysis by SEM and TEM, in the obtained alloy sample or workpiece, the submicron size of Nb5Si3 particles in the obtained microstructure is 300-700nm, and these Nb5Si3 particles are dispersed.

[0086] Example 6 Electron Beam Selective Melting Forming

[0087] (1) The refractory high entropy alloy system is Nb25-Ti13-Zr12-Hf15-V15-Mo10-Ta10, and the construction size is 15×15×70mm 3 The 3D CAD model of the rectangular test block of refractory alloy to be prepared is then sliced ​​in layers at a height of 70 mm, and the scanning path is filled for each slice. The slice information and scanning path information are then imported into the electron beam selective melting forming system.

[0088] (2) First, the powder bed is preheated using a defocused electron beam. The preheating temperature is adjustable to 600 °C to slightly consolidate the alloy powder.

[0089] (3) Each layer of powder is heated, melted and solidified according to the path generated by the computer, and then accumulated layer by layer until the alloy sample is prepared. The forming parameters of the electron beam selective melting are: the forming vacuum is maintained at 2×10 -3 ±0.5×10-4 mbar, operating voltage 60kV, electron beam power set to 500W, and powder layer thickness of 50μm. In this way, Nb5Si3 / Nb (Ti, Zr, Hf, Nb, Mo, Ta) refractory high-entropy alloy materials or parts reinforced with submicron Nb5Si3 particles were prepared by powder-laying electron beam additive manufacturing.

[0090] The effect obtained in this embodiment is that, through SEM detection and analysis, in the obtained alloy sample or workpiece, the submicron size of Nb5Si3 particles in the obtained microstructure is 150-500nm, and these Nb5Si3 particles are dispersed.

[0091] Finally, the refractory high-entropy alloy materials / articles prepared in Examples 3 to 6 are subjected to a homogenization heat treatment at 1400±50°C for 10 to 40 hours under argon protection. 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, generating even finer nanoscale Nb5Si3 particles. Thus, the refractory high-entropy alloy material / article will exhibit a Nb5Si3 / Nb(X,Y,Z...) refractory high-entropy alloy material / article with enhanced dispersion of nano / submicron Nb5Si3 particles. Here, the nano Nb5Si3 particles will have a better strengthening effect than the submicron Nb5Si3 particles.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. 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: 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 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 to 20 μm and Si powder with a particle size of 1 to 5 μm. The Nb-based refractory high-entropy alloy is an alloy of Nb and a high melting point element, and the high melting point element is one or more of Ti, Zr, Hf, Nb, V, Ta and Mo.

2. The method according to claim 1, characterized in that 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 In the process of preparing 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, characterized in that: After the solid phase pressureless sintering, a plasma spheroidization treatment step is also included. During the plasma spheroidization treatment, the current is 600-800A, the main gas flow is 110-130SCFH, the auxiliary gas flow is 5-15SCFH, the carrier gas flow is 10-15SCFH, and the powder feeding rate is 1.5-3r / min.

5. The method according to claim 1, characterized in that The spherical powder of Nb-based refractory high entropy alloy is prepared from the melted Nb-based alloy rod by the rotating electrode atomization method; In the rotary electrode atomization process, 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 feed 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, characterized in that The in-situ reaction using laser is to use a powder feeding laser additive manufacturing method or a laser selective melting method to perform in-situ reaction; In the powder feeding laser additive manufacturing, the laser power is 700-1000W, the scanning speed is 600mm / min, and the powder feeding rate is 1000r / min; The power of the laser selective melting is 250-300W, the scanning speed is 900-1300mm / s, the scanning interval is 0.11mm, and the layer thickness is 50μm.

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

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, a homogenization heat treatment is performed to obtain a 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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