CN110629059A - A kind of heterogeneous high entropy alloy material and preparation method thereof - Google Patents

Abstract

The invention discloses a heterogeneous high-entropy alloy material and a preparation method thereof, comprising four steps of chip making, chip mixing and pre-compaction, plastic deformation treatment, and annealing treatment, and selecting two or more types with different crystal grains Single-phase and dual-phase structure high-entropy alloys with refinement effect, plastic deformation after fully mixing their debris, and complete mechanical alloying of debris through high temperature and high strain, to obtain dense, multi-component mixed heterogeneous high-entropy alloys block blanks. After subsequent annealing heat treatment, a heterogeneous structure with mixed multi-scale grains is formed. The soft-hard combined heterogeneous structure of the present invention can form significant back stress strengthening during the deformation process, thereby preparing a heterogeneous high-entropy alloy with high strength and toughness.

Description

A kind of heterogeneous high entropy alloy material and preparation method thereof

technical field

The invention relates to a heterogeneous high-entropy alloy material and a preparation method thereof, belonging to the field of metal material preparation.

Background technique

A high-entropy alloy is a new type of metal material that is mixed with five or more elements in an equiatomic or approximately equiatomic ratio, where the atomic content of each element is between 5% and 35%. By rationally optimizing the types and proportions of elements, high-entropy alloys can form solid solution structures such as body-centered cubic, face-centered cubic, and two-phase mixtures, thereby exhibiting some excellent properties, such as good corrosion resistance and radiation resistance. , thermal stability, and high strength, hardness and wear resistance. However, like traditional metal materials, the contradiction between strength and toughness of high-entropy alloys still exists, and its characteristics are hard and brittle, or soft and tough. How to simultaneously improve the strength and toughness of high-entropy alloys and prepare high-strength and tough materials is currently a research hotspot in the field of metal materials.

Through literature search to prior art, X.L.Wu et al published "Heterogeneous lamella" in "Proceedings of the National Academy of Science of the United States of America" Proceedings of the American Academy of Sciences, 2015, 112 (47): 14501-14505 In the article "structure units ultrafine-grain strength with coarse-grain ductility" (high-strength, high-toughness coarse-fine-grain mixed layer sheet structure material), through rolling deformation technology and heat treatment process, the strength is close to 1GPa, and the uniform elongation is about 10%. High-strength and high-toughness pure titanium plate. This pure titanium material has a hard ultra-fine grain and soft coarse-grain mixed layer lamellar structure, and the back stress strengthening induced by the coordination of deformation of the soft-hard phase heterogeneous structure can achieve both the high strength of the ultra-fine grain to a certain extent. And the high toughness of coarse grains, thus greatly improving the mechanical properties of pure titanium. However, the mixed crystal pure titanium material prepared by this technology has relatively single components and poor thermal stability.

The pressure processing composite method is another effective method for preparing high-strength and tough metal composite materials. Further search found that Chinese invention patent CN106064504A introduced a preparation method of high-strength and toughness magnesium-lithium alloy layered composite materials. and annealing process, the α-Mg single-phase magnesium-lithium alloy sheet with high strength and the β-Li single-phase magnesium-lithium alloy sheet with good plasticity and toughness are combined to prepare an α/β alternating magnesium-lithium alloy layer Composite materials, composite panels have both high strength and good plasticity. At the same time, the difference in plastic deformation ability between the α-Mg phase and the β-Li phase is used to realize the formation of the "rolling zone", and the interface bonding effect of the composite plate is good. However, the limitation of this method is that the preparation process of the composite sheet is relatively cumbersome, and the sheet for rolling needs to be cut, polished, fixed, and heated multiple times, and the production efficiency is low.

Contents of the invention

The object of the present invention is to provide a heterogeneous high-entropy alloy material and a preparation method thereof in view of the above-mentioned deficiencies in the prior art.

The present invention is achieved through the following technical solutions, comprising the following steps:

The first step, shavings: According to the difference in mechanical properties of high-entropy alloys, at least each of the high-entropy alloys with FCC (face-centered cubic) single-phase structure and FCC+BCC (face-centered cubic + body-centered cubic) dual-phase structure is selected. One: the high-entropy alloy has different grain refinement effects in subsequent deformation and heat treatment processes.

Chip milling is carried out on high-entropy alloy ingots, and the feed rate of chips is controlled between 0.01 and 0.5mm; the coarse chips after milling are finely broken, so as to further reduce the size of chips and make the size of chips more accurate. uniform.

Further, a micro vertical milling machine is used for chip milling, and then a micro crusher is used for fine crushing.

In order to avoid problems such as poor material interface bonding caused by the oxidation of high-entropy alloy debris, the high-entropy alloy chip-making process is carried out in an oxygen-insulated inert gas (argon) atmosphere and in an inert gas (argon) protective box.

The second step, chip mixing and pre-compacting: in an oxygen-barrier inert gas (argon) atmosphere, the dissimilar high-entropy alloy chips are fully stirred and mixed by a ball mill; the chip mixing time is controlled between 0.5 and 2 hours, The frequency of vibration and agitation of the ball mill is set at 10-300 Hz; after the chip mixing process is completed, the mixed fine chips are put into a mold and placed on a press to be pressed into an initial mixed fine chip prefabricated block.

Further, the working pressure of the press is 100-3000 MPa, the pressing temperature is 25-300° C., the holding time is controlled between 10 and 60 minutes, and the density of the obtained prefabricated blocks is between 80% and 98%.

Further, after the prefabricated block is pressed, the sample is vacuum-packaged, and then taken out of the argon gas protection box for use.

Further, a high-energy ball mill is used to fully stir and mix the dissimilar high-entropy alloy chips.

The third step is plastic deformation treatment: the deformation treatment is divided into two steps: conventional extrusion and room temperature rolling; The control is between 10 and 60 minutes; then the pre-pressed billet is extruded and deformed, and the extrusion ratio is 5:1 to 50:1; finally, the extruded sheet is rolled at room temperature, and the rolling deformation is 50%- 90%.

The fourth step, annealing treatment: perform annealing treatment on the rolled sample, the annealing temperature is set at 700-750° C., and the annealing time is 60-90 minutes. Eliminate the defects generated during the deformation process, and at the same time form a soft and hard phase heterogeneous structure with different fine-grain strengthening effects in the bulk material.

Compared with the prior art, the present invention has significant advantages:

1. The patent of the present invention adopts the double-alloy or multi-alloy debris mixed mechanical alloying technology, which has great microstructure design directionality and control flexibility. The alloy selection can be adjusted according to the demand, and a series of soft and hard alloys are prepared. High-entropy alloys are constructed, and the prepared alloys have both the high strength of the hard phase and the high toughness of the soft phase to a certain extent, so as to obtain high-strength and toughness dual-system or multi-system heterogeneous high-entropy alloys with excellent comprehensive properties.

2. The heterogeneous high-entropy alloy with a combination of soft and hard prepared in the present invention has good thermal stability, and the mixed multi-grain-scale microstructure has no obvious directionality, and is suitable for application on multi-directional stress-bearing parts.

3. The present invention can prepare large-sized high-entropy alloy plates, and has relatively low requirements for equipment and molds.

4. The raw material used in the present invention can be industrial waste, the preparation process is simple, the cost is low, the recovery rate is high, the safety is high, energy saving and environmental protection. Compared with traditional industrial waste recycling, the present invention has greater adaptability to common problems such as waste purification and classification.

Description of drawings

Fig. 1 is a schematic diagram of chip making, chip mixing and flow chart of the present invention, respectively.

Fig. 2 is a schematic diagram of the pre-compaction process of the present invention.

Fig. 3 is the schematic flow chart of plastic deformation processing of the present invention.

Fig. 4 is a schematic diagram of the microstructure of the material prepared in the present invention.

Figure 5 is a diagram of the mechanical properties of the prepared heterogeneous high-entropy alloy material.

Detailed ways

The following is a detailed description of the examples.

Example 1

As shown in Figures 1-4, the following embodiments include a four-step process, namely: chip making, chip mixing and pre-compaction, plastic deformation treatment, and annealing treatment, wherein:

As shown in Figure 1, in a vacuum glove box 1 filled with argon protection, a micro vertical milling machine 2 is used to pair CoCrFeNiMn (face-centered cubic single-phase structure) and Al _0.3 CoCrFeNi (face-centered cubic + body-centered cubic dual-phase structure) ) Two high-entropy alloys were used for chip preparation, and the milling feed rate was 0.2 mm, and coarse chips with a thickness of about 0.2 mm were obtained. Then use the micro-crusher 3 to finely crush the milled coarse chips, reduce and uniform the length of the chips to 0.2-0.3mm for later use.

As shown in Figure 2, in the vacuum glove box 1 filled with argon protection, the CoCrFeNiMn and Al _0.3 CoCrFeNi high-entropy alloy chips are mechanically alloyed and mixed by using a micro ball mill 4, such as vibration, stirring, and shaking, and the mixing time is For 60 minutes, the vibration frequency of the ball mill was 100 Hz. After the mixed chips are fully completed, the chips are filled into the steel pressing mold 5, and the cavity size is a square of 50×50mm. Use the micro-press 6 to pre-press the debris. The working pressure of the press is 300 MPa, the pressing temperature is 250° C., and the holding time is 30 minutes to obtain a prefabricated block 7 with a density of about 80%. After the pressing is completed, vacuum seal the prefabricated samples and take them out of the glove box for later use.

As shown in Figure 3, the pre-compressed high-entropy alloy ingot 7 is preheated under an argon atmosphere by using a vacuum furnace 8, the heating temperature is 550 ° C, and the heating time is 30 minutes; The compacted material is subjected to conventional extrusion deformation of 50×50mm to 30×30mm; finally, the extruded plate is rolled at room temperature on the rolling mill 10, and the rolling deformation is 90%, thereby significantly increasing the material density to more than 99%.

As shown in Figure 4, the rolled high-entropy alloy sample is annealed at 700°C in an argon protective atmosphere using a high-temperature vacuum furnace 11 for 60 minutes to obtain a heterogeneous high-entropy alloy with a combination of soft and hard. The schematic diagram of the microstructure of the entropy alloy material is shown in Fig. 4b. Due to the different grain refinement effects of CoCrFeNiMn and Al _0.3 CoCrFeNi high-entropy alloys annealed at 700 °C, such a microstructure with mixed multi-scale grains is formed.

Example 2

As shown in Figures 1-4, the following embodiments include a four-step process, namely: chip making, chip mixing and pre-compaction, plastic deformation treatment, and annealing treatment, wherein:

As shown in Figure 1, in a vacuum glove box 1 filled with argon protection, a micro vertical milling machine 2 is used to pair CoCrFeNiMn (face-centered cubic single-phase structure) and Al _0.3 CoCrFeNi (face-centered cubic + body-centered cubic dual-phase structure) ) two high-entropy alloys were used for chip preparation, and the milling feed rate was 0.1 mm, and coarse chips with a thickness of about 0.1 mm were obtained. Then use the micro-crusher 3 to finely crush the milled coarse chips, reduce and uniform the length of the chips to 0.1-0.2mm for later use.

As shown in Figure 2, in the vacuum glove box 1 filled with argon protection, the CoCrFeNiMn and Al _0.3 CoCrFeNi high-entropy alloy chips are mechanically alloyed and mixed by using a micro ball mill 4, such as vibration, stirring, and shaking, and the mixing time is For 90 minutes, the vibration frequency of the ball mill was 200 Hz. After the mixed chips are fully completed, the chips are filled into the steel pressing mold 5, and the cavity size is a square of 50×50mm. Use the micro press 6 to pre-press the chips. The working pressure of the press is 500 MPa, the pressing temperature is 250° C., and the holding time is 60 minutes to obtain a prefabricated block 7 with a density of about 85%. After the pressing is completed, vacuum seal the prefabricated samples and take them out of the glove box for later use.

As shown in Figure 3, the pre-compressed high-entropy alloy ingot 7 is preheated under an argon atmosphere by using a vacuum furnace 8, the heating temperature is 550 ° C, and the heating time is 60 minutes; The compacted material is subjected to conventional extrusion deformation of 50×50mm to 30×30mm; finally, the extruded plate is rolled at room temperature on the rolling mill 10, and the rolling deformation is 90%, thereby significantly increasing the material density to more than 99%.

As shown in Figure 4, the rolled high-entropy alloy sample is annealed at 700°C in an argon protective atmosphere using a high-temperature vacuum furnace 11, and the annealing time is 90 minutes to prepare a high-strength alloy with mixed multi-scale grains. Ductile heterogeneous high-entropy alloys.

Example 3

As shown in Figures 1-4, the following embodiments include a four-step process, namely: chip making, chip mixing and pre-compaction, plastic deformation treatment, and annealing treatment, wherein:

As shown in Figure 1, in a vacuum glove box 1 filled with argon protection, a micro vertical milling machine 2 is used to pair CoCrFeNiMn (face-centered cubic single-phase structure) and Al _0.3 CoCrFeNi (face-centered cubic + body-centered cubic dual-phase structure) ) two high-entropy alloys were used for chip preparation, and the milling feed rate was 0.1 mm, and coarse chips with a thickness of about 0.1 mm were obtained. Then use the micro-crusher 3 to finely crush the milled coarse chips, reduce and uniform the length of the chips to 0.1-0.2mm for later use.

As shown in Figure 2, in the vacuum glove box 1 filled with argon protection, the CoCrFeNiMn and Al _0.3 CoCrFeNi high-entropy alloy chips are mechanically alloyed and mixed by using a micro ball mill 4, such as vibration, stirring, and shaking, and the mixing time is 120 minutes, the vibration frequency of the ball mill is 300 Hz. After the mixed chips are fully completed, the chips are filled into the steel pressing mold 5, and the cavity size is a square of 50×50mm. Use the micro press 6 to pre-press the debris. The working pressure of the press is 500 MPa, the pressing temperature is 300° C., and the holding time is 60 minutes to obtain a prefabricated block 7 with a density of about 90%. After the pressing is completed, vacuum seal the prefabricated samples and take them out of the glove box for later use.

As shown in Figure 3, the pre-compressed high-entropy alloy ingot 7 is preheated under an argon atmosphere by using a vacuum furnace 8, the heating temperature is 550 ° C, and the heating time is 60 minutes; The compacted material is subjected to conventional extrusion deformation of 50×50mm to 30×30mm; finally, the extruded plate is rolled at room temperature on the rolling mill 10, and the rolling deformation is 90%, thereby significantly increasing the material density to more than 99%.

As shown in Figure 4, the rolled high-entropy alloy sample is annealed at 725°C in an argon protective atmosphere using a high-temperature vacuum furnace 11, and the annealing time is 90 minutes to prepare a high-strength alloy with mixed multi-scale grains. Ductile heterogeneous high-entropy alloys.

The tensile strength and elongation at break of the original CoCrFeNiMn high-entropy alloy are 650MPa and 40%, respectively, which are characterized by low strength and good tensile plasticity; while the original Al _0.3 CoCrFeNi high-entropy alloy is characterized by hard and brittle texture, and its tensile strength Up to 1000MPa, but the elongation at break is only 8%. The high-strength toughness heterogeneous high-entropy alloy prepared by the invention fully combines the advantages of the above two materials, the tensile strength is as high as 950MPa, and the fracture elongation is 35%.

Claims (7)

1. a preparation method of heterogeneous high-entropy alloy material, is characterized in that, the method is The first step, shavings: According to the difference in mechanical properties of high-entropy alloys, at least one of the high-entropy alloys with FCC single-phase structure and FCC+BCC dual-phase structure is selected; chip milling is performed on high-entropy alloy ingots , the feed rate of chips is controlled between 0.01 and 0.5mm; the coarse chips after milling are finely broken; The second step, chip mixing and pre-compaction: In an oxygen-barrier inert gas atmosphere, the dissimilar high-entropy alloy chips are fully stirred and mixed by a ball mill; the chip mixing time is controlled between 0.5 and 2 hours, and the ball mill vibrates and stirs The frequency is set at 10-300 Hz; after the chip mixing process is completed, the mixed chips are put into the mold and placed on the press, and pressed into the initial mixed chips prefabricated blocks; The third step, plastic deformation treatment: first preheat the pre-pressed billet in a vacuum furnace, the pre-heating temperature is set at 400-600 ° C, and the pre-heating time is controlled between 10 and 60 minutes; then the pre-pressed billet is pre-heated extrusion deformation, the extrusion ratio is 5:1 to 50:1; finally, room temperature rolling is carried out on the extruded plate, and the rolling deformation is 50%-90%; The fourth step, annealing treatment: annealing treatment is carried out on the rolled sample, the annealing temperature is set at 700-750°C, and the annealing time is 60-90 minutes; the defects generated during the deformation process are eliminated, and different Soft and hard phase heterogeneous structure with fine grain strengthening effect. 2. The preparation method of heterogeneous high-entropy alloy material according to claim 1, characterized in that, adopting a miniature vertical milling machine to carry out chip milling, and adopting a micro-crusher to carry out fine crushing. 3. The method for preparing the heterogeneous high-entropy alloy material according to claim 1, wherein the shavings are carried out in an oxygen-barrier inert gas atmosphere. 4. The preparation method of heterogeneous high-entropy alloy material according to claim 1, characterized in that, the working pressure of the press is 100-3000 MPa, the pressing temperature is 25-300°C, and the holding time is controlled Between 10 and 60 minutes, a prefabricated block density between 80% and 98% is obtained. 5. The preparation method of heterogeneous high-entropy alloy material according to claim 1, characterized in that, after the prefabricated block is pressed, the sample is vacuum-packaged, and then taken out from the argon gas protection box for later use. 6. The preparation method of heterogeneous high-entropy alloy material according to claim 1, characterized in that, the heterogeneous high-entropy alloy chips are fully stirred and mixed by using a high-energy ball mill. 7. A heterogeneous high-entropy alloy material, characterized in that the high-entropy alloy material is prepared by the preparation method described in any one of claims 1-6.