阅读说明：本技术 高熵晶界修饰的铁基多元纳米晶合金及其制备方法 (High-entropy grain boundary modified iron-based multi-element nanocrystalline alloy and preparation method thereof ) 是由 陈正 樊宇 孔维维 王振宇 杨小芹 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种高熵晶界修饰的铁基多元纳米晶合金及其制备方法,所述纳米晶合金的组分包括铁、第一金属、第二金属、第三金属和第四金属,其中,所述第一金属为锆,所述第二金属为铌,所述第三金属为钽,所述第四金属为铪或钼。根据本发明实施例的高熵晶界修饰的铁基多元纳米晶合金,通过将其组分设置为包括铁、第一金属、第二金属、第三金属和第四金属,在高温下可以有效地抑制晶粒长大,有效地提高了纳米晶合金的热稳定性能。(The invention discloses a high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy and a preparation method thereof. According to the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy disclosed by the embodiment of the invention, the components of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy are set to comprise iron, a first metal, a second metal, a third metal and a fourth metal, so that the grain growth can be effectively inhibited at high temperature, and the thermal stability of the nanocrystalline alloy is effectively improved.)

1. The high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy is characterized in that the nanocrystalline alloy comprises iron, a first metal, a second metal, a third metal and a fourth metal, wherein the first metal is zirconium, the second metal is niobium, the third metal is tantalum, and the fourth metal is hafnium or molybdenum.

2. The high-entropy grain boundary-modified iron-based multi-element nanocrystalline alloy of claim 1, characterized in that: the nanocrystalline alloy comprises the following components in percentage by mass: the mass fraction of the first metal is 0.1-3.0%, the mass fraction of the second metal is 0.1-3.0%, the mass fraction of the third metal is 0.1-3.0%, the mass fraction of the fourth metal is 0.1-3.0%, and the balance is iron.

3. The high-entropy grain boundary-modified iron-based multi-element nanocrystalline alloy of claim 2, wherein: the mass fractions of the first metal, the second metal, the third metal and the fourth metal are equal.

4. A high entropy grain boundary modified iron-based multi-nanocrystalline alloy according to any one of claims 1-3, characterized in that: the nanocrystalline alloy comprises nanocrystalline grains, and the nanocrystalline grains have a structure that the first metal, the second metal, the third metal and the fourth metal cover the surface of the iron.

5. A preparation method of a high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy is characterized by comprising the following steps:

s100: weighing iron powder, the first metal powder, the second metal powder, the third metal powder and the fourth metal powder, and uniformly mixing to form mixed metal powder;

s200: sealing the mixed metal powder and the dispersing agent in a ball milling tank under an inert gas environment, and carrying out ball milling to nano-convert the mixed metal powder to obtain nanocrystalline alloy powder;

s300: and sintering the nanocrystalline alloy powder at high temperature and high pressure to obtain the bulk nanocrystalline alloy.

6. The method according to claim 5, wherein step S300 comprises:

and (2) loading the nanocrystalline alloy powder into an equipment cavity of the hexahedral top press, heating the pressure in the equipment cavity to 1-5 GPa, heating the temperature to 700-1000 ℃, preserving the temperature for 10-50 min, and then cooling the temperature of the equipment cavity to room temperature to ensure that the first metal, the second metal, the third metal and the fourth metal are partially gathered at the boundary of nanocrystalline alloy crystal grains to form a high-entropy crystal boundary.

7. The preparation method according to claim 5, wherein in the step S200, the rotation speed of the ball mill is 150-400 r/min and the ball milling time is 15-50 h in the ball milling process.

8. The method of claim 5, wherein: in the step S200, the ball mill is paused for 10-20 min every 30min in the ball milling process.

9. The method according to claim 5, wherein the grain size of the bulk nanocrystalline alloy is 50nm to 90 nm.

10. The high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy is characterized by being prepared by the preparation method of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy according to any one of claims 4-9.

Technical Field

The invention relates to the technical field of alloy materials, in particular to a high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy and a preparation method thereof.

Background

Compared with the common coarse-crystal material, the nano-crystal material (the grain size is less than 100nm) has a series of excellent physical and mechanical properties mainly represented by high hardness or strength due to small grain size and large proportion of grain boundary area. The nanocrystalline alloy material shows wide application prospect as a novel high-performance material. However, nanocrystalline alloy materials are prone to grain growth at higher temperatures, and have poor thermodynamic stability, thereby losing their excellent properties.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention aims to provide a high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy which is good in thermal stability.

The invention also aims to provide a preparation method of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy.

The invention further aims to provide the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy prepared by the preparation method.

The high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy comprises iron, a first metal, a second metal, a third metal and a fourth metal, wherein the first metal is zirconium, the second metal is niobium, the third metal is tantalum, and the fourth metal is hafnium or molybdenum.

According to the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy disclosed by the embodiment of the first aspect of the invention, the components of the alloy are set to comprise iron, the first metal, the second metal, the third metal and the fourth metal, so that the grain growth can be effectively inhibited at high temperature, and the thermal stability of the nanocrystalline alloy is effectively improved.

According to some embodiments of the invention, the nanocrystalline alloy comprises, in mass percent: the mass fraction of the first metal is 0.1-3.0%, the mass fraction of the second metal is 0.1-3.0%, the mass fraction of the third metal is 0.1-3.0%, the mass fraction of the fourth metal is 0.1-3.0%, and the balance is iron.

According to some embodiments of the invention, the mass fractions of the first metal, the second metal, the third metal and the fourth metal are equal.

According to some embodiments of the invention, the nanocrystalline alloy comprises nanocrystalline grains having a structure in which the first metal, the second metal, the third metal, and the fourth metal cover a surface of the iron.

The preparation method of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy according to the second aspect of the invention comprises the following steps:

s100: weighing iron powder, the first metal powder, the second metal powder, the third metal powder and the fourth metal powder, and uniformly mixing to form mixed metal powder;

s200: sealing the mixed metal powder and the dispersing agent in a ball milling tank under an inert gas environment, and carrying out ball milling to nano-convert the mixed metal powder to obtain nanocrystalline alloy powder;

s300: and (3) carrying out high-temperature high-pressure sintering treatment on the nanocrystalline alloy powder by adopting a hexahedral top press to obtain the block nanocrystalline alloy.

According to some embodiments of the invention, step S300 comprises: and (2) loading the nanocrystalline alloy powder into an equipment cavity of the hexahedral top press, heating the pressure in the equipment cavity to 1-5 GPa, heating the temperature to 700-1000 ℃, preserving the temperature for 10-50 min, and then cooling the temperature of the equipment cavity to room temperature to ensure that the first metal, the second metal, the third metal and the fourth metal are partially gathered at the boundary of nanocrystalline alloy crystal grains to form a high-entropy crystal boundary.

According to some embodiments of the invention, in the step S200, the rotation speed of the ball mill is 150 to 400r/min during ball milling, and the ball milling time is 15 to 50 hours.

According to some embodiments of the invention, in the step S200, the ball mill is paused for 10-20 min every 30min of operation.

According to some embodiments of the invention, the grain size of the grains in the nanocrystalline alloy powder is 10nm to 20 nm.

According to some embodiments of the invention, the grains in the bulk nanocrystalline alloy have a grain size in the range of 50nm to 90 nm.

The high-entropy grain boundary modified iron-based multi-component nanocrystalline alloy according to the third aspect of the invention is prepared by the preparation method of the second aspect.

The principle of the invention is as follows: the iron-based pure metal powder is prepared into the nanocrystalline alloy in a mechanical alloying mode. The principle that the high entropy effect brought by the fact that the grain boundary energy and the multicomponent solute are co-segregated to the grain boundary is reduced by solute segregation is utilized, and the components of the high-temperature high-strength iron-based nanocrystalline alloy are designed. The nanocrystalline alloy has higher strength due to smaller grain size, but has wider grain boundary area, larger grain boundary energy in the temperature rise process and faster grain size increase. By designing and optimizing the grain boundary, the grain boundary energy of the nano iron-based alloy is further reduced, and the method is an important way for improving the thermal stability and retaining high strength. A plurality of alloy elements with strong segregation effects are added into the iron-based alloy, the alloy elements are segregated to grain boundaries in the heating process, the co-segregation of a plurality of groups of solute brings the reduction of the grain boundary energy, meanwhile, the alloy elements form a high-entropy phase at the grain boundaries, the grain boundaries can be further reduced due to the higher entropy, and the thermal stability of the iron-based nanocrystalline alloy is further improved thermodynamically. Meanwhile, a second phase formed at a crystal boundary after a plurality of elements are segregated can also appear in the temperature rising process, the crystal boundary is pinned on dynamics, the growth of the crystal grain is hindered, and the thermal stability of the iron-based nanocrystalline alloy is improved.

Zirconium Zr, niobium Nb, molybdenum Mo, tantalum Ta or zirconium Zr, niobium Nb, hafnium Hf, tantalum Ta are selected as solute elements of the iron-based nanocrystalline alloy, and the solute elements have large segregation enthalpies in an iron matrix and are easy to segregate to a crystal boundary in the temperature rise process. More than four components can form a high-entropy phase, namely a high-entropy grain boundary is formed. The multicomponent solute cosegregation and the high-entropy crystal boundary thermodynamically reduce the crystal boundary energy of the nanocrystalline iron-based alloy, the thermal stability is improved, the grain size is smaller after the temperature is raised, and the strength is stronger.

Compared with the prior production technology of the iron-based nanocrystalline alloy, the invention has the remarkable advantages that:

(1) the invention adopts mechanical alloying to prepare the iron-based nanocrystalline alloy powder, and prepares the high-temperature and high-strength iron-based nanocrystalline bulk alloy by a high-temperature and high-pressure technology, and the preparation process is simple and clear and is convenient to operate.

(2) The raw materials needed for preparing the iron-based nanocrystalline alloy are easy to obtain, the used proportion of solute elements is small, and the cost is low.

(3) The prepared crystal grain size is extremely small, and the crystal grain size can be regulated and controlled to a certain degree through a production process and element addition amount.

(4) The iron-based nanocrystalline block alloy obtained by the method has extremely high strength and strong thermal stability. Has higher use value as a structural material.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is an XRD pattern of a bulk nanocrystalline alloy according to an embodiment of the present invention;

FIG. 2 is an XRD pattern of a bulk nanocrystalline alloy according to another embodiment of the present invention;

fig. 3 is an XRD pattern of a bulk nanocrystalline alloy according to yet another embodiment of the invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

The high entropy grain boundary modified iron-based multi-component nanocrystalline alloy according to an embodiment of the present invention is described below. It is understood that the nanocrystalline alloy may be in powder form or in bulk form.

Steel is an important pillar in the traditional industry and is representative of ferrous based materials. The national manufacturing industry is continuously developed and advanced, and the existing performance indexes of the traditional iron-based material are broken through to become the research hotspots in the field of materials. The introduction of nanotechnology in the preparation of traditional metal materials has become a powerful means to improve the material properties. Higher temperatures are often present under practical production conditions and during practical use of the material. Nanocrystalline alloys with poor thermal stability are prone to grain growth and loss of their excellent properties. The improvement of the thermal stability of the iron-based nanocrystalline material is more important.

In order to solve the technical problem of poor thermal stability of a nanocrystalline alloy material, the invention provides a high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy, which comprises the components of iron (Fe), a first metal, a second metal, a third metal and a fourth metal, wherein the first metal is zirconium (Zr), the second metal is niobium (Nb), the third metal is tantalum (Ta), and the fourth metal is hafnium (Hf) or molybdenum (Mo). Wherein the iron may be a matrix, and the first metal, the second metal, the third metal, and the fourth metal may be solute components.

Specifically, in some embodiments, the composition of the nanocrystalline alloy includes iron, zirconium, niobium, hafnium, and tantalum, the nanocrystalline alloy being expressed as Fe-ZrNbHfTa. In other embodiments, the composition of the nanocrystalline alloy includes iron, zirconium, niobium, molybdenum, and tantalum, the nanocrystalline alloy being expressed as Fe-ZrNbMoTa.

Zirconium Zr, niobium Nb, molybdenum Mo, tantalum Ta or zirconium Zr, niobium Nb, hafnium Hf and tantalum Ta are selected as solute elements of the iron-based nanocrystalline alloy, the solute elements have large segregation enthalpies in an iron matrix, the solute elements are easy to segregate to grain boundaries in the heating process, and the grain boundary energy can be reduced by solute co-segregation of various components. Meanwhile, more than four components can form a high-entropy phase, namely a high-entropy grain boundary is formed, and the higher entropy can further reduce the grain boundary energy of the nanocrystalline alloy, so that the thermal stability of the iron-based nanocrystalline alloy is improved thermodynamically. In addition, a second phase formed at a crystal boundary after various elements are segregated can also appear in the nanocrystalline alloy in the temperature rising process, the crystal boundary is pinned on dynamics, the growth of crystal grains is hindered, the nanocrystalline alloy can still keep the size of the nano-scale crystal grains after the temperature rising, and the thermal stability of the iron-based nanocrystalline alloy is further improved.

According to the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy disclosed by the embodiment of the first aspect of the invention, the components of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy are set to comprise iron, a first metal, a second metal, a third metal and a fourth metal, so that the grain growth can be effectively inhibited at high temperature, and the thermal stability of the nanocrystalline alloy is effectively improved.

According to some embodiments of the invention, the nanocrystalline alloy comprises, in mass percent: the mass fraction of the first metal is 0.1-3.0%, the mass fraction of the second metal is 0.1-3.0%, the mass fraction of the third metal is 0.1-3.0%, the mass fraction of the fourth metal is 0.1-3.0%, and the balance is iron. The mass fraction of iron is 1-the mass fraction of the first metal-the mass fraction of the second metal-the mass fraction of the third metal-the mass fraction of the fourth metal.

For example, in some embodiments, the mass fraction of the first metal is 0.1%, 0.2%, 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc. The mass fraction of the second metal is 0.1%, 0.2%, 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc. The mass fraction of the third metal is 0.1%, 0.2%, 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc. The mass fraction of the fourth metal is 0.1%, 0.2%, 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc. The mass fractions of the first metal, the second metal, the third metal and the fourth metal may be adjusted according to actual needs, which is not specifically limited in the present invention. It is understood that the mass fractions of the first metal, the second metal, the third metal and the fourth metal may be equal or may not be equal. Therefore, the dosage of solute elements can be reduced on the basis of ensuring higher thermal stability of the nanocrystalline alloy, and the cost of the nanocrystalline alloy is favorably reduced.

According to some embodiments of the present invention, the nanocrystalline alloy includes nanocrystalline grains having a structure in which the first metal, the second metal, the third metal, and the fourth metal cover a surface of the iron. The nanocrystalline grains may be spherical or polygonal. Therefore, the structure of the nanocrystalline alloy is more stable, and the thermal stability is higher.

The preparation method of the high-entropy grain boundary modified iron-based multi-component nanocrystalline alloy according to the second aspect of the invention is described below.

The preparation method of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy comprises the following steps:

s100: weighing iron powder, first metal powder, second metal powder, third metal powder and fourth metal powder, and uniformly mixing to form mixed metal powder;

s200: sealing the mixed metal powder and a dispersing agent (such as normal hexane or alcohol) into a ball milling tank under an inert gas environment (such as argon) for ball milling, so that the mixed metal powder is subjected to nanocrystallization to obtain nanocrystalline alloy powder;

specifically, the ball mill can be filled in a ball mill for ball milling. In some embodiments, the rotation speed during ball milling is 150-400 r/min, the ball milling time is 15-50 h, the ball mill is suspended for 10-20 min every 30min until nanocrystalline alloy powder is prepared, and the grain size of the iron-based nanocrystalline alloy powder after ball milling is 10-20 nm.

S300: and sintering the nanocrystalline alloy powder at high temperature and high pressure to obtain the bulk nanocrystalline alloy. For example, a hexahedral press may be used to perform a high-temperature high-pressure sintering process on the nanocrystalline alloy powder.

Step S300 specifically includes: the nanocrystalline alloy powder is loaded into the equipment cavity of the hexahedral top press, for example, the nanocrystalline alloy powder can be loaded into a boron nitride crucible, and then the boron nitride crucible is placed into the equipment cavity of the hexahedral top press. And then, adding the pressure in the equipment cavity to 1-5 GPa, heating to 700-1000 ℃, preserving the temperature for 10-50 min, and then cooling the temperature of the equipment cavity to room temperature to ensure that the first metal, the second metal, the third metal and the fourth metal are partially gathered at the boundary of the nanocrystalline alloy crystal grain to form a high-entropy crystal boundary.

In the bulk nanocrystalline alloy prepared by the preparation method of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy, the grain size is 50nm-90 nm. Therefore, the size of the crystal grains of the nanocrystalline alloy can be smaller, and the thermal stability of the iron-based nanocrystalline alloy can be improved.

The present invention is further illustrated by the following specific examples.

Example 1

According to the mass percentage, the proportion of the nanocrystalline alloy is 99.2 percent of iron, 0.2 percent of zirconium, 0.2 percent of niobium, 0.2 percent of molybdenum and 0.2 percent of tantalum. The raw materials are all metal powder with the purity of 99.95 percent.

The method is characterized in that a plurality of pure metal powders mainly containing iron are subjected to nanocrystallization by adopting a mechanical alloying method, and then the iron-based nanocrystalline alloy powder is prepared into the high-strength high-thermal-stability iron-based nanocrystalline bulk alloy by adopting a high-temperature high-pressure technology for solidification and sintering. The method comprises the following specific steps:

weighing iron powder, zirconium powder, niobium powder, molybdenum powder and tantalum powder according to the mass ratio of 99.2% of iron, 0.2% of zirconium, 0.2% of niobium, 0.2% of molybdenum and 0.2% of tantalum, and uniformly mixing to form mixed metal powder;

sealing mixed metal powder and a dispersing agent (normal hexane) into a ball milling tank under an inert gas environment (argon), loading the ball milling tank into a ball milling machine, carrying out ball milling, wherein the rotating speed during ball milling is 250r/min, the ball milling time is 50h, pausing for 15min every 30min during the ball milling process, preserving heat for 5h at 70 ℃ by using a vacuum oven after ball milling, and then sampling;

and (3) loading the powder into a boron nitride crucible and placing the boron nitride crucible into a cavity of a cubic press, pressurizing to 4GPa, heating the sample to 800 ℃, preserving the temperature for 30min, and cooling to room temperature along with the furnace to obtain the iron-based multi-element nanocrystalline bulk alloy.

Example 2

The proportion of the nanocrystalline alloy is 98% of iron, 0.5% of zirconium, 0.5% of niobium, 0.5% of molybdenum and 0.5% of tantalum according to the mass percentage. The raw materials are all metal powder with the purity of 99.95 percent.

The method is characterized in that a plurality of pure metal powders mainly containing iron are subjected to nanocrystallization by adopting a mechanical alloying method, and then the iron-based nanocrystalline alloy powder is prepared into the nanocrystalline bulk alloy with high strength, high heat stability by adopting a high-temperature high-pressure technology for solidification and sintering. The method comprises the following specific steps:

weighing iron powder, zirconium powder, niobium powder, molybdenum powder and tantalum powder according to the mass ratio of 98% of iron, 0.5% of zirconium, 0.5% of niobium, 0.5% of molybdenum and 0.5% of tantalum, and uniformly mixing to form mixed metal powder;

sealing mixed metal powder and a dispersing agent (normal hexane) into a ball milling tank under an inert gas environment (argon), loading the ball milling tank into a ball milling machine, carrying out ball milling, wherein the rotating speed during ball milling is 250r/min, the ball milling time is 50h, pausing for 15min every 30min during the ball milling process, preserving heat for 5h at 70 ℃ by using a vacuum oven after ball milling, and then sampling;

loading the powder into a boron nitride crucible and putting the boron nitride crucible into a cavity of a cubic press, pressurizing to 4GPa, heating the sample to 800 ℃, preserving the temperature for 30min, and cooling to room temperature along with the furnace to obtain the iron-based multi-element nanocrystalline bulk alloy

Example 3

According to the mass percentage, the proportion of the nanocrystalline alloy is 99.2 percent of iron, 0.2 percent of zirconium, 0.2 percent of niobium, 0.2 percent of hafnium and 0.2 percent of tantalum. The raw materials are all metal powder with the purity of 99.95 percent.

The method is characterized in that a plurality of pure metal powders mainly containing iron are subjected to nanocrystallization by adopting a mechanical alloying method, and then the iron-based nanocrystalline alloy powder is prepared into the nanocrystalline bulk alloy with high strength, high heat stability by adopting a high-temperature high-pressure technology for solidification and sintering. The method comprises the following specific steps:

weighing iron powder, zirconium powder, niobium powder, hafnium powder and tantalum powder according to the mass ratio of 99.2% of iron, 0.2% of zirconium, 0.2% of niobium, 0.2% of hafnium and 0.2% of tantalum, and uniformly mixing to form mixed metal powder;

sealing mixed metal powder and a dispersing agent (normal hexane) into a ball milling tank under an inert gas environment (argon), loading the ball milling tank into a ball milling machine, carrying out ball milling, wherein the rotating speed during ball milling is 250r/min, the ball milling time is 50h, pausing for 15min every 30min during the ball milling process, preserving heat for 5h at 70 ℃ by using a vacuum oven after ball milling, and then sampling;

and (3) loading the powder into a boron nitride crucible and placing the boron nitride crucible into a cavity of a cubic press, pressurizing to 4GPa, heating the sample to 800 ℃, preserving the temperature for 30min, and cooling to room temperature along with the furnace to obtain the iron-based multi-element nanocrystalline bulk alloy.

Fig. 1 to 3 are XRD patterns of bulk alloys prepared in examples 1 to 3. Wherein fig. 2 is an XRD pattern of the bulk alloy prepared in example 2, and fig. 3 is an XRD pattern of the bulk alloy prepared in example 2.

Fig. 1 is an XRD pattern of the bulk alloy prepared in example 1, and a full spectrum fit calculation of the data resulted in an average grain size of 77nm of the bulk alloy prepared in example 1. It can be seen that the bulk nanocrystalline alloy obtained after high-temperature and high-pressure sintering still maintains the nanoscale and shows better thermal stability.

Fig. 2 is an XRD pattern of the bulk alloy prepared in example 2, and a full spectrum fit calculation of the data resulted in an average grain size of 65nm for the bulk alloy prepared in example 1. It can be seen that the bulk nanocrystalline alloy obtained after high-temperature and high-pressure sintering still maintains the nanoscale and shows better thermal stability.

Fig. 3 is an XRD pattern of the bulk alloy prepared in example 3, and a full spectrum fit calculation is performed on the data to obtain an average grain size of 71nm for the bulk alloy prepared in example 3. It can be seen that the bulk nanocrystalline alloy obtained after high-temperature and high-pressure sintering still maintains the nanoscale and shows better thermal stability.

In addition, the mechanical property test results of the bulk alloys prepared in examples 1 to 3 are shown in table 1.

TABLE 1 mechanical Properties of the bulk alloys prepared in examples 1-3

As can be seen from table 1, the bulk nanocrystalline alloy prepared according to the present invention exhibits extremely excellent mechanical properties. The Vickers hardness of bulk nanocrystalline Fe-Zr0.2Nb0.2Mo0.2Ta0.2, Fe-Zr0.5Nb0.5Mo0.5Ta0.5 and Fe-Zr0.2Nb0.2Hf0.2Ta0.2 alloys is 724HV, HV 721 and 726HV respectively, the compressive strength is 3586MPa, 3530MPa and 3557MPa respectively, the yield strength is 3480MPa, 3491MPa and 3420MPa respectively, and the elongation is 4.77%, 4.68% and 4.32% respectively.

The preparation method of the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy according to the embodiment of the second aspect of the invention has the following advantages:

(1) the invention adopts mechanical alloying to prepare the iron-based nanocrystalline alloy powder, and prepares the high-temperature and high-strength iron-based nanocrystalline bulk alloy by a high-temperature and high-pressure technology, and the preparation process is simple and clear and is convenient to operate.

(2) The raw materials needed for preparing the iron-based nanocrystalline alloy are easy to obtain, the used proportion of solute elements is small, and the cost is low.

(3) The prepared crystal grain size is extremely small, and the crystal grain size can be regulated and controlled to a certain degree through a production process and element addition amount.

(4) The iron-based nanocrystalline block alloy obtained by the method has extremely high strength and strong thermal stability, and has higher use value as a structural material.

The high-entropy grain boundary modified iron-based multi-component nanocrystalline alloy according to the third aspect of the invention is prepared by the preparation method of the second aspect.

According to the high-entropy grain boundary modified iron-based multi-element nanocrystalline alloy disclosed by the embodiment of the third aspect of the invention, the iron-based multi-element nanocrystalline alloy is prepared by the preparation method disclosed by the embodiment of the second aspect, the size of crystal grains is small, the thermal stability is high, the preparation method is simple, the operation is convenient, the materials are easy to obtain, and the cost is low.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.