阅读说明：本技术 一种高耐蚀非等摩尔高熵合金及其制备方法 (High-corrosion-resistance non-equimolar high-entropy alloy and preparation method thereof ) 是由 杨贺杰 孙佳鹏 高义民 于 2021-08-05 设计创作，主要内容包括：一种高耐蚀非等摩尔高熵合金及其制备方法,其中NiFeCrRuMoW高熵合金的组元为Ni、Fe、Cr、Ru、Mo、W。本发明采用机械混粉以及球磨来实现机械合金化,再通过放电等离子体烧结制备出综合性能良好的NiFeCrRuMoW耐蚀高熵合金材料,其组织均匀,强度硬度等性能均较好。为探究最佳的制备条件,选用正交实验法进行三因素三水平的变量设计,因素为球磨时间、烧结压力和烧结温度。最终制得的最佳合金抗压强度高于2000Mpa,屈服强度高于1100Mpa,硬度大于550HV,腐蚀率仅为0.1107mm/年,耐蚀性极其优越。此外,该合金的制备流程简单,易于进行产业化生产,可以作为核电产业中核废料储存容器的结构材料。(A high-corrosion-resistance non-equimolar high-entropy alloy and a preparation method thereof are disclosed, wherein the NiFeCrRuMoW high-entropy alloy comprises components of Ni, Fe, Cr, Ru, Mo and W. The invention adopts mechanical powder mixing and ball milling to realize mechanical alloying, and then prepares the NiFeCrRuMoW corrosion-resistant high-entropy alloy material with good comprehensive performance by discharge plasma sintering, and the NiFeCrRuMoW corrosion-resistant high-entropy alloy material has uniform tissue and good properties such as strength and hardness. In order to explore the optimal preparation conditions, an orthogonal experimental method is selected to carry out three-factor three-level variable design, wherein the factors are ball milling time, sintering pressure and sintering temperature. The finally prepared optimal alloy has the compressive strength higher than 2000MPa, the yield strength higher than 1100MPa, the hardness higher than 550HV, the corrosion rate of only 0.1107 mm/year and extremely excellent corrosion resistance. In addition, the alloy has simple preparation process, is easy to carry out industrialized production, and can be used as a structural material of a nuclear waste storage container in nuclear power industry.)

1. The high-corrosion-resistance non-equimolar high-entropy alloy is characterized in that the high-entropy alloy comprises the following components in percentage by mass: ni: 33-34%, Fe: 16-17%, Cr: 16-17%, Ru: 19-20%, Mo: 8-9%, W: 5-6 percent.

2. A preparation method of a high-corrosion-resistance non-equimolar high-entropy alloy is characterized by comprising the following steps of:

the method comprises the following steps: ingredients

Taking Ni: 33-34%, Fe: 16-17%, Cr: 16-17%, Ru: 19-20%, Mo: 8-9%, W: 5-6% of powder ingredients;

step two: ball mill

Putting the proportioned powder into a ball milling tank with a polytetrafluoroethylene lining for ball milling by a dry milling method, and obtaining Ni-Fe-Cr-Ru-Mo-W composite powder after the ball milling is finished;

step three: spark plasma sintering

And (2) filling the Ni-Fe-Cr-Ru-Mo-W composite powder into a graphite mold, putting the mold into a discharge plasma sintering furnace, vacuumizing the sintering furnace, heating from room temperature to 600 ℃ at a heating rate of 100K/min, preserving heat, heating to 950-1050 ℃ at a heating rate of 100K/min, sintering, and cooling to room temperature along with the furnace after sintering is finished to obtain the NiFeCrRuMoW corrosion-resistant high-entropy alloy.

3. The method for preparing the high-corrosion-resistance non-equimolar high-entropy alloy as claimed in claim 2, wherein: ni, Fe, Cr, Ru, Mo and W in the first step are added in the form of elementary powder.

4. The method for preparing the high-corrosion-resistance non-equimolar high-entropy alloy as claimed in claim 3, wherein: in the first step, the granularity of the elementary substance powder Ru is 100 microns, and the granularity of the rest Ni, Fe, Cr, Mo and W is 35-45 microns.

5. The method for preparing the high-corrosion-resistance non-equimolar high-entropy alloy as claimed in claim 2, wherein: and the ball milling in the second step is carried out by using a planetary ball mill, the ball milling rotating speed is 300r/min, the ball-material ratio is 10:1, the ball milling mode is forward and reverse rotation operation, the ball milling is stopped for 10 minutes every 20 minutes, and the ball milling time is 30-50 hours.

6. The method for preparing the high-corrosion-resistance non-equimolar high-entropy alloy as claimed in claim 2, wherein: and step three, keeping the temperature at 600 ℃ for 1 minute.

7. The method for preparing the high-corrosion-resistance non-equimolar high-entropy alloy as claimed in claim 2, wherein: the sintering pressure in the third step is 20-60 Mpa, and the sintering time is 10 min.

Technical Field

The invention relates to a high-corrosion-resistance high-entropy alloy and a preparation method thereof, in particular to a high-corrosion-resistance non-equimolar high-entropy alloy and a preparation method thereof.

Background

The high-entropy alloy is a novel material prepared by adopting a novel alloy design concept, is different from the traditional alloy design concept that only one element is taken as a main body and other elements are added to improve the performance of the high-entropy alloy, and has the characteristics that: the main component types are five or more, the content of each main component is between 5% and 35%, and no main component is dominant. The high-entropy alloy has the advantages of high strength, high hardness, high corrosion resistance, high wear resistance, high temperature resistance, good soft magnetism and the like, and is widely applied to a plurality of fields of chemical pipelines, high-speed cutting tools, golf ball head striking surfaces, oil pressure air pressure rods, motor magnetic cores, turbine blades and the like.

The high-entropy alloy has better corrosion resistance, because in a corrosive working condition, a thicker passive film can be quickly formed on the HEA surface, the current density of corrosion reaction is reduced, a lower corrosion rate is shown, and the high-entropy alloy is particularly suitable for severe working conditions such as strong acid, high salt and the like. With the rapid development of the nuclear power field, the problem of storing nuclear waste is becoming more serious, and because the nuclear waste releases heat in the fission process to cause temperature rise, alloy materials with excellent corrosion resistance are generally adopted as corresponding storage containers. The requirements on the corrosion resistance and the mechanical property related to a container for storing nuclear waste are higher and higher, and other service requirements such as strong wear resistance and the like are also considered, so that the high-entropy alloy with high corrosion resistance and high mechanical property has a better application prospect in the future.

Compared with the traditional corrosion-resistant alloy, for example, SS316L stainless steel which is currently widely applied to structural materials in the field of acid resistance and corrosion resistance has the following components: 0.08 wt.%, Mn: 2.0 wt.%, Si: 0.75 wt.%, Cr: 16-18 wt.%, Ni: 10-14 wt.%, P: 0.045 wt.%, S: 0.03 wt.%, the remainder being Fe. Under the same experimental conditions, the corrosion resistance rate of SS316L stainless steel is 1837mm/year, which is much higher than that of the high-entropy alloy prepared by the method. The traditional single-principal-element corrosion-resistant alloy represented by the alloy obviously cannot meet the working condition requirement of a nuclear waste container in the nuclear power industry. Therefore, it is urgent to invent a new corrosion-resistant alloy material with superior corrosion resistance and strength.

In the current research, the most widely used method in the research of high-entropy alloys is a vacuum arc melting method, and the specific method is as follows: in the protective atmosphere, the metal elements are completely melted by plasma arc heating of the electrode, and then the alloy is solidified into the alloy by rapid cooling through water cooling temperature. The method has the advantages of high purity of the prepared alloy, high yield of the alloy, prevention of influence of foreign impurities and the like, but also has the defects of difficult control of volatile elements and the like, and simultaneously, the cast alloy has a series of problems of internal stress, shrinkage cavity and the like due to expansion with heat and contraction with cold in the casting process, so that the finally prepared alloy has poor performance.

As a powder metallurgy method, the mechanical alloying-discharge plasma sintering method is increasingly widely applied to the preparation of high-entropy alloy, and the specific flow is as follows: the powder is refined and homogenized by high-energy ball milling, and then the metal powder is subjected to pressure sintering by direct electrification of direct-current pulse current. Compared with a vacuum arc melting method, the mechanical alloying-discharge plasma sintering method has the remarkable advantages of high temperature rise speed, short sintering time, low sintering temperature, uniform crystal grains, convenience in controlling the microstructure of a sintered body, high density of obtained materials and the like, and is simple and convenient to operate and low in cost, so that the mechanical alloying-discharge plasma sintering method is selected as a preparation method.

Disclosure of Invention

The invention aims to provide a high-corrosion-resistance non-equimolar high-entropy alloy and a preparation method thereof, wherein the preparation process is simple, and the high-corrosion-resistance non-equimolar high-entropy alloy is easy to carry out industrial production.

In order to achieve the aim, the high-corrosion-resistance non-equimolar high-entropy alloy comprises the following components in percentage by mass: ni: 33-34%, Fe: 16-17%, Cr: 16-17%, Ru: 19-20%, Mo: 8-9%, W: 5-6 percent.

The preparation method comprises the following steps:

the method comprises the following steps: ingredients

Taking Ni: 33-34%, Fe: 16-17%, Cr: 16-17%, Ru: 19-20%, Mo: 8-9%, W: 5-6% of powder ingredients;

step two: ball mill

Putting the proportioned powder into a ball milling tank with a polytetrafluoroethylene lining for dry ball milling to obtain Ni-Fe-Cr-Ru-Mo-W composite powder after ball milling is finished;

step three: spark plasma sintering

And (2) filling the Ni-Fe-Cr-Ru-Mo-W composite powder into a graphite mold, putting the mold into a discharge plasma sintering furnace, vacuumizing the sintering furnace, heating from room temperature to 600 ℃ at a heating rate of 100K/min, preserving heat, heating to 950-1050 ℃ at a heating rate of 100K/min, sintering, and cooling to room temperature along with the furnace after sintering is finished to obtain the NiFeCrRuMoW corrosion-resistant high-entropy alloy.

Ni, Fe, Cr, Ru, Mo and W in the first step are added in the form of elementary powder.

In the first step, the granularity of the elementary substance powder Ru is 100 microns, and the granularity of the rest Ni, Fe, Cr, Mo and W is 35-45 microns.

And the ball milling in the second step is carried out by using a planetary ball mill, the ball milling rotating speed is 300r/min, the ball-material ratio is 10:1, the ball milling mode is forward and reverse rotation operation, the ball milling is stopped for 10 minutes every 20 minutes, and the ball milling time is 30-50 hours.

And step three, keeping the temperature at 600 ℃ for 1 minute.

The sintering pressure in the third step is 20-60 Mpa, and the sintering time is 10 min.

Compared with the existing corrosion-resistant alloy and other high-entropy alloys, the invention has the following beneficial effects:

the discharge plasma sintering method for preparing the NiFeCrRuMoW corrosion-resistant high-entropy alloy has the characteristics of high temperature rise speed and simplicity in operation, the total time consumption in the process of sintering the single alloy is no more than one hour, and the efficiency is high.

The corrosion-resistant high-entropy alloy prepared by the method has a BCC-FCC structure, uniform metallographic structure, sample porosity of less than 1%, microhardness value of 450-550HV, room-temperature compressive strength up to 2000Mpa, excellent corrosion resistance and corrosion resistance rate of only 0.1-0.2 mm/year.

Drawings

FIG. 1 shows the X-ray diffraction pattern of the Ni-Fe-Cr-Ru-Mo-W high corrosion resistant non-equimolar high entropy alloy prepared in example 1 of the present invention, indicating that the alloy phases prepared by the present invention are Body Centered Cubic (BCC) and Face Centered Cubic (FCC).

FIG. 2 shows a scanning electron microscope image of a Ni-Fe-Cr-Ru-Mo-W high corrosion resistant non-equimolar high entropy alloy prepared in example 1 of the present invention, indicating that the alloy prepared in the present invention comprises three different structures.

FIG. 3 shows the room temperature compression curve of the Ni-Fe-Cr-Ru-Mo-W high corrosion resistant non-equimolar high entropy alloy prepared in example 1 of this invention. The strength of the material is obviously improved, the compression strength is 2040MPa at room temperature, and the elongation at break is 20.6%.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.

Example 1:

in the embodiment, the Ni-Fe-Cr-Ru-Mo-W corrosion-resistant high-entropy alloy comprises the following components in percentage by mass: ni: 33.3 wt.%, Fe: 16.31 wt.%, Cr: 16.68 wt.%, Ru: 19.62 wt.%, Mo: 8.6 wt.%, W: 5.49 wt.%.

The original powder particle size was: except that the particle diameter of Ru powder is 100 micrometers, the particle sizes of the rest Ni powder, Fe powder, Cr powder, Mo powder and W powder are 35-45 micrometers.

In this embodiment, the method for preparing the corrosion-resistant high-entropy alloy of 30 to 40 to 1050 (the number indicates that the ball milling is performed for 30 hours, the sintering pressure is 40Mpa, and the sintering temperature is 1050 ℃), includes the following steps:

step 1: ingredients

Weighing six metal powders of Ni, Fe, Cr, Ru, Mo and W according to the mass ratio, and transferring the metal powders into a ball milling tank with a 500mL capacity and a polytetrafluoroethylene lining;

step 2: ball mill

And after the proportioned powder is transferred, a planetary ball mill is used, a dry milling mode is selected for ball milling, the ball milling is carried out according to the rotation speed of 300r/min and the ball-material ratio of 10:1 in a manner that the ball mill rotates in a positive and negative direction, the ball mill stops 10 minutes every 20 minutes of operation to prevent overheating, and the ball milling time is selected to be 30 hours. After the ball milling is finished, Ni-Fe-Cr-Ru-Mo-W composite powder is obtained.

And step 3: spark plasma sintering

And (3) loading the Ni-Fe-Cr-Ru-Mo-W composite powder prepared in the step (II) into a graphite mold with the diameter of 10mm, putting the mold into a discharge plasma sintering furnace, vacuumizing the sintering furnace, heating to 600 ℃ at the heating rate of 100K/min, preserving heat at 600 ℃ for 1 minute, heating to 1050 ℃ at the heating rate of 100K/min, preserving heat for 10 minutes, and cooling to room temperature after heat preservation is finished to obtain the NiFeCrRuMoW corrosion-resistant high-entropy alloy. The pressure during sintering was set at a constant 40 MPa. And during sintering, the temperature rising speed is selected to be 100K/min, and after sintering is finished, the cooling mode is furnace cooling.

It can be seen from FIG. 1 that the alloy structure prepared by the present invention is a body centered cubic-face centered cubic (BCC-FCC) structure.

From fig. 2, it can be seen that the alloy prepared by the invention has a more uniform structure and a smaller porosity of only 0.874%.

As can be seen from FIG. 3, the hardness average value of the high-entropy alloy prepared by the invention is 454Hv, which is superior to that of the conventional stainless steel material (the microhardness is 220-300 Hv). The strength of the material is obviously improved, the compressive yield strength at room temperature is 1150MPa, the compressive strength at room temperature is 2040MPa, and the elongation at break is 20.6%.

Example 2:

in the embodiment, the Ni-Fe-Cr-Ru-Mo-W corrosion-resistant high-entropy alloy comprises the following components in percentage by mass: ni: 33.3 wt.%, Fe: 16.31 wt.%, Cr: 16.68 wt.%, Ru: 19.62 wt.%, Mo: 8.6 wt.%, W: 5.49 wt.%.

The original powder particle size was: except that the particle diameter of Ru powder is 100 micrometers, the particle sizes of the rest Ni powder, Fe powder, Cr powder, Mo powder and W powder are 35-45 micrometers.

In this embodiment, a method for preparing a corrosion-resistant high-entropy alloy of 40-40-1050 (where the number indicates ball milling for 40 hours, sintering pressure is 40Mpa, and sintering temperature is 1050 ℃), includes the following steps:

step 1: ingredients

Weighing six metal powders of Ni, Fe, Cr, Ru, Mo and W according to the mass ratio, and transferring the metal powders into a ball milling tank with a 500mL capacity and a polytetrafluoroethylene lining;

step 2: ball mill

And after the proportioned powder is transferred, a planetary ball mill is used, a dry milling mode is selected for ball milling, the ball milling is carried out according to the rotation speed of 300r/min and the ball-material ratio of 10:1 in a manner that the ball mill rotates in a positive and negative direction, the ball mill stops 10 minutes every 20 minutes of operation to prevent overheating, and the ball milling time is selected to be 40 hours. After the ball milling is finished, Ni-Fe-Cr-Ru-Mo-W composite powder is obtained.

And step 3: spark plasma sintering

And (3) loading the Ni-Fe-Cr-Ru-Mo-W composite powder prepared in the step (II) into a graphite mold with the diameter of 10mm, putting the mold into a discharge plasma sintering furnace, vacuumizing the sintering furnace, heating to 600 ℃ at the heating rate of 100K/min, preserving heat at 600 ℃ for 1 minute, heating to 1050 ℃ at the heating rate of 100K/min, preserving heat for 10 minutes, and cooling to room temperature after heat preservation is finished to obtain the NiFeCrRuMoW corrosion-resistant high-entropy alloy. The pressure during sintering was set at a constant 40 MPa. And during sintering, the temperature rising speed is selected to be 100K/min, and after sintering is finished, the cooling mode is furnace cooling.

The crystal structure of the sintered high-entropy alloy is a body centered cubic-face centered cubic (BCC-FCC) structure, the structure is relatively uniform, and the porosity is relatively low and is only 0.423%. The hardness mean value 545Hv of the high-entropy alloy is superior to that of a conventional stainless steel material (microhardness 220-300 Hv). The strength of the material is high, the compressive yield strength is 870MPa at room temperature, and the compressive strength is 1920 MPa.

Example 3:

in the embodiment, the Ni-Fe-Cr-Ru-Mo-W corrosion-resistant high-entropy alloy comprises the following components in percentage by mass: ni: 33.3 wt.%, Fe: 16.31 wt.%, Cr: 16.68 wt.%, Ru: 19.62 wt.%, Mo: 8.6 wt.%, W: 5.49 wt.%.

The original powder particle size was: except that the particle diameter of Ru powder is 100 micrometers, the particle sizes of the rest Ni powder, Fe powder, Cr powder, Mo powder and W powder are 35-45 micrometers.

In the embodiment, the preparation method of the corrosion-resistant high-entropy alloy with the temperature of 50-40-1050 (the number indicates that the ball milling is carried out for 40 hours, the sintering pressure is 40Mpa, and the sintering temperature is 1050 ℃) comprises the following steps:

step 1: ingredients

Weighing six metal powders of Ni, Fe, Cr, Ru, Mo and W according to the mass ratio, and transferring the metal powders into a ball milling tank with a 500mL capacity and a polytetrafluoroethylene lining;

step 2: ball mill

And after the proportioned powder is transferred, a planetary ball mill is used, a dry milling mode is selected for ball milling, the ball milling is carried out according to the rotation speed of 300r/min and the ball-material ratio of 10:1 in a manner that the ball mill rotates in a positive and negative direction, the ball mill stops 10 minutes every 20 minutes of operation to prevent overheating, and the ball milling time is selected to be 50 hours. After the ball milling is finished, Ni-Fe-Cr-Ru-Mo-W composite powder is obtained.

And step 3: spark plasma sintering

And (3) loading the Ni-Fe-Cr-Ru-Mo-W composite powder prepared in the step (II) into a graphite mold with the diameter of 10mm, putting the mold into a discharge plasma sintering furnace, vacuumizing the sintering furnace, heating to 600 ℃ at the heating rate of 100K/min, preserving heat at 600 ℃ for 1 minute, heating to 1050 ℃ at the heating rate of 100K/min, preserving heat for 10 minutes, and cooling to room temperature after heat preservation is finished to obtain the NiFeCrRuMoW corrosion-resistant high-entropy alloy. The pressure during sintering was set at a constant 40 MPa. And during sintering, the temperature rising speed is selected to be 100K/min, and after sintering is finished, the cooling mode is furnace cooling.

The crystal structure of the sintered high-entropy alloy is a body centered cubic-face centered cubic (BCC-FCC) structure, the structure is relatively uniform, and the porosity is relatively low and is only 0.478%. The average value of the hardness of the high-entropy alloy is 451Hv, which is superior to that of a conventional stainless steel material (the microhardness is 220-300 Hv). The material has higher strength, the compressive yield strength is 700MPa at room temperature, and the compressive strength is 1290 MPa.

Example 4:

in the embodiment, the Ni-Fe-Cr-Ru-Mo-W corrosion-resistant high-entropy alloy comprises the following components in percentage by mass: ni: 34%, Fe: 16%, Cr: 16%, Ru: 19%, Mo: 9%, W: 6 percent.

The original powder particle size was: except that the particle diameter of Ru powder is 100 micrometers, the particle sizes of the rest Ni powder, Fe powder, Cr powder, Mo powder and W powder are 35-45 micrometers.

In this embodiment, the preparation method of the corrosion-resistant high-entropy alloy of 30-20-950 (the number indicates that the ball milling is performed for 30 hours, the sintering pressure is 20Mpa, and the sintering temperature is 950 ℃), includes the following steps:

step 1: ingredients

Weighing six metal powders of Ni, Fe, Cr, Ru, Mo and W according to the mass ratio, and transferring the metal powders into a ball milling tank with a 500mL capacity and a polytetrafluoroethylene lining;

step 2: ball mill

And after the proportioned powder is transferred, a planetary ball mill is used, a dry milling mode is selected for ball milling, the ball milling is carried out according to the rotation speed of 300r/min and the ball-material ratio of 10:1 in a manner that the ball mill rotates in a positive and negative direction, the ball mill stops 10 minutes every 20 minutes of operation to prevent overheating, and the ball milling time is selected to be 30 hours. After the ball milling is finished, Ni-Fe-Cr-Ru-Mo-W composite powder is obtained.

And step 3: spark plasma sintering

And (3) loading the Ni-Fe-Cr-Ru-Mo-W composite powder prepared in the step (II) into a graphite mold with the diameter of 10mm, putting the mold into a discharge plasma sintering furnace, vacuumizing the sintering furnace, heating to 600 ℃ at the heating rate of 100K/min, preserving heat at 600 ℃ for 1 minute, heating to 950 ℃ at the heating rate of 100K/min, preserving heat for 10 minutes, and cooling to room temperature after the heat preservation is finished to obtain the NiFeCrRuMoW corrosion-resistant high-entropy alloy. The pressure during sintering was set at a constant 20 MPa. And during sintering, the temperature rising speed is selected to be 100K/min, and after sintering is finished, the cooling mode is furnace cooling.

Example 5:

in the embodiment, the Ni-Fe-Cr-Ru-Mo-W corrosion-resistant high-entropy alloy comprises the following components in percentage by mass: ni: 33%, Fe: 17%, Cr: 17%, Ru: 20%, Mo: 8%, W: 5 percent.

The original powder particle size was: except that the particle diameter of Ru powder is 100 micrometers, the particle sizes of the rest Ni powder, Fe powder, Cr powder, Mo powder and W powder are 35-45 micrometers.

In this embodiment, the method for preparing a corrosion-resistant high-entropy alloy of 50 to 60 to 1000 (the number indicates that the ball milling is performed for 50 hours, the sintering pressure is 60Mpa, and the sintering temperature is 1000 ℃), includes the following steps:

step 1: ingredients

Weighing six metal powders of Ni, Fe, Cr, Ru, Mo and W according to the mass ratio, and transferring the metal powders into a ball milling tank with a 500mL capacity and a polytetrafluoroethylene lining;

step 2: ball mill

And after the proportioned powder is transferred, a planetary ball mill is used, a dry milling mode is selected for ball milling, the ball milling is carried out according to the rotation speed of 300r/min and the ball-material ratio of 10:1 in a manner that the ball mill rotates in a positive and negative direction, the ball mill stops 10 minutes every 20 minutes of operation to prevent overheating, and the ball milling time is selected to be 50 hours. After the ball milling is finished, Ni-Fe-Cr-Ru-Mo-W composite powder is obtained.

And step 3: spark plasma sintering

And (3) loading the Ni-Fe-Cr-Ru-Mo-W composite powder prepared in the step (II) into a graphite mold with the diameter of 10mm, putting the mold into a discharge plasma sintering furnace, vacuumizing the sintering furnace, heating to 600 ℃ at the heating rate of 100K/min, preserving heat at 600 ℃ for 1 minute, heating to 1000 ℃ at the heating rate of 100K/min, preserving heat for 10 minutes, and cooling to room temperature after heat preservation is finished to obtain the NiFeCrRuMoW corrosion-resistant high-entropy alloy. The pressure during sintering was set at a constant 60 MPa. And during sintering, the temperature rising speed is selected to be 100K/min, and after sintering is finished, the cooling mode is furnace cooling.