阅读说明：本技术 一系列FeCoCrNiW(VC)X高熵合金的制备及其沉淀强化工艺 (A series of FeCoCrNiW (VC)XPreparation of high-entropy alloy and precipitation strengthening process thereof ) 是由 张乾坤 唐俊 肖逸锋 吴靓 钱锦文 李苏望 陈泽民 陈豫章 于 2020-06-23 设计创作，主要内容包括：本发明属于高熵合金技术领域,具体涉及到一系列FeCoCrNiW(VC)<Sub>x</Sub>高熵合金的制备及其沉淀强化工艺。高熵合金的材料的成分为(FeCoCrNiW)<Sub>100-x</Sub>(VC)<Sub>x</Sub>,(x＝0,0.5,1at％)。具体的制备步骤：1)分别称取原材料粉末,对称取的原料进行湿磨、混合与干燥处理；2)通过粉末压样机用长条形模具压成条形粉块；3)然后采用非自耗真空熔炼炉对材料进行多次熔炼；4)依次对铸锭进行全固溶处理和半固溶与沉淀强化处理。相比于其他传统高熵合金,本发明制备的FeCoCrNiW(VC)<Sub>x</Sub>高熵合金,通过双固溶处理后析出大量纳米级沉淀相,得到了组织均匀细小,且强硬度高、塑韧性好的高熵合金。弥补了传统合金的不足,可应用于机械加工领域。(The invention belongs to the technical field of high-entropy alloy, and particularly relates to a series of FeCoCrNiW (VC) x Preparation of high-entropy alloy and precipitation strengthening process thereof. The material of the high-entropy alloy comprises the following components (FeCoCrNiW) 100‑x (VC) x (x ═ 0,0.5,1 at%). The preparation method comprises the following specific steps: 1) respectively weighing raw material powder, and carrying out wet grinding, mixing and drying treatment on the weighed raw materials; 2) pressing into strip-shaped powder blocks by a strip-shaped die through a powder sample press; 3) then, smelting the material for multiple times by adopting a non-consumable vacuum smelting furnace; 4) and carrying out full solid solution treatment and semi-solid solution and precipitation strengthening treatment on the cast ingot in sequence. Compared with other traditional high-entropy alloys, FeCoCrNiW (VC) prepared by the invention) x The high-entropy alloy is subjected to double solid solution treatment to precipitate a large amount of nanoscale precipitated phases, so that the high-entropy alloy with uniform and fine structure, high hardness and good ductility and toughness is obtained. Makes up the defects of the traditional alloy and can be applied to the field of machining.)

1. A series of FeCoCrNiW (VC)_xThe preparation method of the high-entropy alloy is characterized by comprising the following steps of: firstly, ball-milling and mechanically mixing the raw material powder of the high-entropy alloy, and pressing the mixture into powder blocks after vacuum drying; step two, smelting the mixture into an ingot in a vacuum smelting furnace according to a certain smelting process; step three, carrying out full solid solution treatment on the high-entropy alloy cast ingot; and step four, carrying out semi-solid solution treatment and aging precipitation strengthening treatment on the high-entropy alloy obtained in the step three.

2. According to claim 1The method is characterized in that the high-entropy alloy component is (FeCoCrNiW)_100-x(VC)_xThe element components (mass percent) are respectively as follows: 10 to 35 parts of iron, 10 to 30 parts of cobalt, 5 to 20 parts of chromium, 5 to 20 parts of nickel, 5 to 20 parts of tungsten and 0 to 25 parts of vanadium carbide.

3. The method as claimed in claim 1, wherein the raw material powder in the first step is one or more of elemental powder or pre-alloyed powder, the particle size of the powder is less than 500 μm, and the purity is greater than or equal to 99%.

4. The method of claim 1, wherein the ball milling parameters in step one are: the grinding balls are made of zirconia balls or hard alloy balls, the ball milling medium is alcohol or n-propane, the ball milling ratio is 2: 1-5: 1, and the ball milling time is 8-16 h.

5. The method of claim 1, wherein the smelting process in step two is: argon low-pressure washing the furnace, vacuumizing until the pressure in the furnace is reduced to 1 multiplied by 10^-3Pa, then introducing high-purity argon to reach 1atm, smelting at a voltage of 30-50V and a current of 250-350 mA, and repeatedly smelting for 3-5 times to obtain the ingot.

6. The method of claim 1, wherein the full solution treatment temperature in step three is 1300 ℃, the temperature is maintained for 2 hours, and then the steel is rapidly quenched to room temperature. The quenching medium is air, distilled water or quenching oil.

7. The method according to claim 1, wherein the high-entropy alloy in the fourth step is subjected to full solid solution treatment, then semi-solid solution treatment is carried out, the temperature is 1100-1200 ℃, the temperature is kept for 1 hour, and then the high-entropy alloy is subjected to oil cooling to room temperature; and then carrying out precipitation strengthening treatment, wherein the precipitation strengthening process comprises the following steps: annealing at 570-650 ℃ for 2-3 times, each for 2-6 hours.

Background

High Entropy Alloy (High Entropy Alloy) is a new Alloy design concept proposed in 90 s of the 20 th century, is also called High chaos Alloy, is different from traditional unit or multi-element Alloy, and is a novel Alloy with five or more main elements, and the content of each main element is 5% -35%. The composite material breaks through the design limitation of the traditional metal material, can obtain the composite material with high strength, high hardness, good wear resistance, corrosion resistance and fatigue resistance, excellent low-temperature and high-temperature mechanical properties and the like through reasonable component design, and has remarkable application potential and development potential. However, it is highly desirable to further improve the toughness and broaden the application range. The high-entropy alloy has four main effects, which are respectively: high entropy effect, lattice distortion effect, slow diffusion effect, cocktail effect. The characteristics are high entropy effect in thermodynamics, lattice distortion effect in structure, slow diffusion effect in kinetics and cocktail effect in performance. The method is easy to obtain a solid solution phase and a nano structure or even an amorphous structure with simple structure and high thermal stability.

Meanwhile, the conventional high-entropy alloy has a large gap in performance, such as: difficult processing, poor toughness, insufficient strong hardness, poor high-temperature performance, no wear resistance and the like. In view of the above problems, in recent years, the properties of high-entropy alloys have been adjusted and improved by solid-solution strengthening, work hardening, precipitation strengthening, and second-phase strengthening. For example, in CN110592457A, a high-entropy alloy with a hexagonal close-packed structure is formed by 14 rare earth elements, although the addition of the rare earth elements promotes the solid solution strengthening effect of the matrix and improves the performance to a certain extent, the hardness and tensile properties of the alloy are far inferior to those of the conventional high-entropy alloy. Further examples are CN110983114A addition The performance of the high-entropy alloy is improved by the nitride, the technological processes of homogenizing annealing, forging and heat treatment are added, the simultaneous implementation of solid solution strengthening, fine grain strengthening and dislocation strengthening is guaranteed, the precipitated nano-nitride also realizes the excellent combination of strength and toughness, but the possibility of oxidative cracking caused by segregation of the alloy is easy to occur due to long-time high-temperature treatment, and the performance is influenced. CN110284042A (Fe)₅₀Mn₂₅Co₁₀Cr₁₅)_0.98The CMo high-entropy alloy plate realizes the high plasticity of the high-entropy alloy by utilizing smelting, hot rolling, solution treatment and cold rolling, the plasticity is superior to that of all the traditional high-entropy alloys on the market, and meanwhile, the corrosion resistance and the wear resistance are correspondingly improved. However, the application range of the high-entropy alloy is limited due to the insufficient strength and hardness of the alloy.

The invention provides a series of FeCoCrNiW (VC)_xThe performance of the high-entropy alloy is further optimized by using double-solid-solution precipitation strengthening treatment, the whole process flow comprises the steps of powder preparation, ball milling, drying, pressing, smelting, full-solid-solution treatment, semi-solid-solution precipitation strengthening treatment and the like, the refining of a material structure can be realized without hot working deformation, and the high-entropy alloy has the characteristics of short flow, low pollution, low energy consumption, high production efficiency and the like. Meanwhile, the high-entropy alloy subjected to full solid solution treatment and semi-solid solution-precipitation strengthening treatment has a uniform and fine structure, a large amount of nanoscale precipitation strengthening phases are precipitated, the toughness of the material is greatly improved, and the high-temperature oxidation resistance and wear resistance are excellent, so that the high-entropy alloy has great development potential and research value.

Disclosure of Invention

The invention aims to develop a series of FeCoCrNiW (VC) with uniform and fine tissues, high strength and hardness and good plasticity and toughness_xHigh entropy alloy.

The invention is realized by the following steps:

step 1: preparation of mixed powder

Series (FeCoCrNiW)_100-x(VC)_xThe high-entropy alloy is characterized in that: (FeCoCrNiW)_100-x(VC)_xPercentage of elements used in high entropy alloyThe ratio is respectively as follows: 10 to 35 parts of iron, 10 to 30 parts of cobalt, 5 to 20 parts of chromium, 5 to 20 parts of nickel, 5 to 20 parts of tungsten and 0 to 25 parts of vanadium carbide. Preferably, x is 0, x is 0.5, and x is 1 as an experimental group, and the elemental raw material powder or the pre-alloyed powder is weighed according to the atomic ratio by using an electronic balance. And putting the weighed powder into a planetary ball mill for mechanical mixing and stirring, and putting the powder slurry prepared after high-energy ball milling into a vacuum drying oven for drying to obtain the mixed powder.

Step 2: press forming

And placing the obtained mixed powder in a long strip-shaped die, and pressing the mixed powder into strip-shaped powder blocks by using a powder sample press.

And step 3: vacuum melting

Cleaning a hearth, dipping the absolute ethyl alcohol by gauze to wipe a workbench of the electric arc furnace and other positions in the furnace, and polishing the tungsten electrode by abrasive paper until the tungsten electrode has a tip. And then, carrying out low-vacuum pre-pumping on the non-consumable vacuum smelting furnace, and introducing argon to wash the furnace. And sequentially placing the strip-shaped powder blocks into sample grooves of a water-cooled copper crucible of a vacuum smelting furnace, and placing titanium ingots into the rest sample grooves. Then, the vacuum is pumped up until the pressure in the furnace is reduced to 1 × 10 ^-3Pa, then introducing high-purity argon to reach 1 atm. And (3) arc striking is carried out at the position of the titanium sheet, so that the raw materials in the sample tank become liquid beads with fluidity, the current is turned off, the alloy ingot is solidified into an alloy ingot, and the alloy ingot is obtained after repeated smelting.

And 4, step 4: full solid solution treatment and semi-solid solution precipitation strengthening treatment

And placing the obtained high-entropy alloy ingot in a well-type resistance furnace for full solid solution treatment and semi-solid solution treatment, and rapidly quenching to room temperature. And then, placing the quenched sample in a tempering furnace for precipitation strengthening treatment, and tempering for 2-3 times.

Furthermore, in the step 1, the raw material powder is one or more of element powder or pre-alloy powder, the particle size of the powder is less than 500 mu m, and the purity is more than or equal to 99%.

Furthermore, in the step 1, the grinding balls are made of zirconia balls or hard alloy balls, the ball milling medium is alcohol or n-propane, the ball milling ratio is 2: 1-5: 1, and the ball milling time is 8-16 h.

Further, the pressing pressure of the powder sample pressing machine in the step 2 is 50-100 MPa, and the pressure maintaining time is 1-2 min.

Further, the setting parameters of the non-consumable vacuum melting furnace in the step 3 are as follows: the voltage is 30-50V, the current is 250-350 mA, the smelting time is 2-3 min, and the smelting times are 3-5.

Further, in the step 4, the temperature of the full solution treatment is 1300 ℃, the time is 2 hours, and the quenching medium is gas or quenching oil.

Further, in the step 4, the semi-solid solution treatment temperature is 1100-1200 ℃, the time is 1 hour, and the quenching medium is distilled water or quenching oil; the tempering temperature required by the precipitation strengthening treatment is 570-650 ℃, and the heat preservation time is 2-6 hours.

The invention has the beneficial effects that:

1. the invention utilizes double solid solution precipitation strengthening treatment to further optimize the performance of the high-entropy alloy, the whole process flow comprises the steps of powder preparation, ball milling, drying, pressing, smelting, full solid solution treatment, semi-solid solution precipitation strengthening treatment and the like, the refinement of the material structure can be realized without hot working deformation, and the invention has the characteristics of short flow, little pollution, less energy consumption, high production efficiency and the like.

2. The high-entropy alloy through full solid solution treatment and semi-solid solution-precipitation strengthening treatment has uniform and fine structure, and simultaneously precipitates a large amount of nano-scale precipitation strengthening phases, thereby greatly improving the toughness of the material and having excellent high-temperature oxidation resistance and wear resistance.

3. Based on the advantages, the new material has a very wide development prospect in the industries of cutters and molds and the field of high-temperature wear resistance.

Drawings

FIG. 1 is FeCoCrNiW (VC) prepared in examples 1-3_xHigh-entropy alloy microhardness test result graph

FIG. 2 is FeCoCrNiW (VC) prepared in example 1_xSEM image of high-entropy alloy microstructure

FIG. 3 is FeCoCrNiW (VC) prepared in example 3_xSEM image of high-entropy alloy microstructure

The specific implementation mode is as follows:

in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention are further illustrated in the following drawings in the specific embodiments. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which are extended without inventive step based on the embodiments of the present invention, and obtained by the person of ordinary skill in the art, are within the scope of the present invention.