阅读说明：本技术 一种无σ相析出倾向的沉淀强化型高熵合金及其制备方法 (Precipitation strengthening type high-entropy alloy without sigma phase precipitation tendency and preparation method thereof ) 是由 刘鑫旺 高腾飞 刘鹏 涂泽立 蒋文明 樊自田 于 2020-06-29 设计创作，主要内容包括：本发明公开了一种无σ相析出倾向的沉淀强化型高熵合金及其制备方法,属于高熵合金领域。所述高熵合金由Fe、Ni、Mn、Cu四种元素采用等摩尔的配比组成。该高熵合金的优选制备方法为：将配好的原料先在真空氩气保护下的电弧炉熔炼,后经过滴铸、均匀化退火、冷轧、时效步骤即得到所述无σ相析出倾向的沉淀强化型高熵合金。所述无σ相析出倾向的沉淀强化型高熵合金室温屈服强度和拉伸强度最优值分别能达到825MPa和933MPa,延伸率大于15％,且其力学性能指标可利用时效参数进行调节。本申请的无σ相析出倾向的沉淀强化型高熵合金在室温下具有优异的综合力学性能。(The invention discloses a precipitation strengthening type high-entropy alloy without sigma phase precipitation tendency and a preparation method thereof, belonging to the field of high-entropy alloys. The high-entropy alloy is composed of four elements of Fe, Ni, Mn and Cu according to an equimolar proportion. The preferred preparation method of the high-entropy alloy comprises the following steps: firstly, smelting the prepared raw materials in an electric arc furnace under the protection of vacuum argon, and then carrying out drop casting, homogenizing annealing, cold rolling and aging to obtain the precipitation strengthening type high-entropy alloy without the sigma phase precipitation tendency. The optimal values of the room-temperature yield strength and the tensile strength of the precipitation-strengthened high-entropy alloy without the sigma phase precipitation tendency can reach 825MPa and 933MPa respectively, the elongation is more than 15%, and the mechanical property index of the precipitation-strengthened high-entropy alloy can be adjusted by using aging parameters. The precipitation strengthening type high-entropy alloy without the sigma phase precipitation tendency has excellent comprehensive mechanical properties at room temperature.)

1. A preparation method of a precipitation strengthening type high-entropy alloy without sigma phase precipitation tendency is characterized in that four pure metal materials of Fe, Ni, Mn and Cu in equal molar ratio are sequentially subjected to smelting, drop casting, homogenizing annealing, cold rolling and aging annealing to obtain the precipitation strengthening type high-entropy alloy without sigma phase precipitation tendency; wherein the content of the first and second substances,

the parameter range of the homogenizing annealing is 910-1050 ℃, and the temperature is kept for 12-48 h; the temperature range of the aging annealing is 800-900 ℃, and the time range is 0.5-1 h.

2. The preparation method of claim 1, wherein Mn is placed at the bottommost layer of the crucible during smelting, and Fe, Ni and Cu are stacked layer by layer from bottom to top in the sequence of melting points from low to high above Mn.

3. The method of claim 2, wherein the smelting process is: smelting in an electric arc smelting furnace under the protection of negative pressure and argon atmosphere.

4. The method of claim 3, wherein the arc melting furnace is evacuated and backfilled with argon to 5 x 10⁴And Pa, repeatedly vacuumizing and backfilling argon twice, and then smelting.

5. The method of claim 1, wherein the cold rolling is performed for a deformation amount of 80% to 90%.

6. The method of claim 5, wherein the cold rolling is performed at a strain level of 85%.

7. The method according to claim 6, wherein the parameters of the homogenizing anneal are 1000 ℃, 12 h; the parameters of the aging annealing are that the temperature is kept for 1h at 800 ℃ or 1h at 850 ℃.

8. The method according to any one of claims 1 to 7, wherein the homogenizing annealing and the aging annealing are both followed by rapid cooling by water-cooling quenching.

9. A precipitation-strengthened high-entropy alloy free from a tendency to precipitate a sigma phase, which is obtained by the production method according to any one of claims 1 to 8.

Technical Field

The invention belongs to the field of high-entropy alloy preparation, and particularly relates to a precipitation-strengthened high-entropy alloy without a sigma phase precipitation tendency and a preparation method thereof.

Background

High-entropy alloys (HEAs) have been proposed to subvert the understanding of traditional alloys. Due to the cocktail effect of high entropy alloys, one can need to blend the alloy components to achieve the desired properties, which greatly opens the way researchers design new materials. High entropy alloys generally refer to alloy systems in which five or more alloying elements are combined in (near) equal atomic ratios, on the basis of which a number of new alloy systems with unique properties have been proposed. Wherein the alloy system with a face-centered cubic structure (FCC) has excellent toughness/plasticity and is considered to have great application potential. However, the alloy systems are widely added with strengthening element Cr, such as a very representative CrMnFeCoNi high-entropy alloy.

A large number of researches show that in the medium-temperature aging process of the CrMnFeCoNi high-entropy alloy, Cr element is easy to induce and separate out a brittle sigma (sigma) phase and/or other compounds, so that the comprehensive mechanical property is reduced. If the precipitation tendency of brittle phases and compounds can be eliminated, the method is greatly helpful for improving the comprehensive mechanical properties of the material.

How to ensure the strength and/or plasticity of the material while eliminating the precipitation tendency of brittle phases and compounds becomes a problem to be solved at present.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a precipitation strengthening type high-entropy alloy without sigma phase precipitation tendency and a preparation method thereof, aiming at only taking four pure metal materials of Fe, Ni, Mn and Cu as raw materials on the premise of not adding Cr, and realizing the purposes of eliminating the precipitation tendency of a brittle (sigma) phase and other compounds and ensuring the strength and/or toughness of the material through the improvement of process steps and process parameters.

In order to achieve the above object, according to one aspect of the present invention, a method for preparing a precipitation-strengthened high-entropy alloy without a sigma phase precipitation tendency is provided, wherein four pure metal materials of Fe, Ni, Mn, and Cu in equal molar ratio are subjected to smelting, drop casting, homogenizing annealing, cold rolling, and aging annealing in sequence to obtain the precipitation-strengthened high-entropy alloy without a sigma phase precipitation tendency; wherein the content of the first and second substances,

the parameter range of the homogenizing annealing is 910-1050 ℃, and the temperature is kept for 12-48 h; the temperature range of the aging annealing is 800-900 ℃, and the time range is 0.5-1 h.

Further, Mn is placed at the bottommost layer of the crucible during smelting, and Fe, Ni and Cu are stacked above Mn layer by layer from bottom to top according to the sequence of melting points from low to high.

Further, the smelting method comprises the following steps: smelting in an electric arc smelting furnace under the protection of negative pressure and argon atmosphere.

Further, the electric arc melting furnace is vacuumized and then backfilled with argon to 5 multiplied by 10⁴And Pa, repeatedly vacuumizing and backfilling argon twice, and then smelting.

Further, cold rolling 80-90% of deformation.

Further, the steel sheet was cold-rolled by 85% deformation.

Further, the parameters of homogenizing annealing are 1000 ℃ and 12 hours; the parameters of the aging annealing are that the temperature is kept for 1h at 800 ℃ or 1h at 850 ℃.

Further, after homogenizing and aging annealing, the steel is rapidly cooled in a water-cooling quenching mode.

In order to achieve the above object, according to another aspect of the present invention, there is provided a precipitation-strengthened high-entropy alloy free from a tendency to precipitate a sigma phase, obtained by the production method as described in any one of the foregoing.

In general, compared with the prior art, the above technical solution contemplated by the present invention can obtain the following beneficial effects:

1. the precipitation strengthening type high-entropy alloy prepared by the method does not contain Cr, and the precipitation tendency of a brittle sigma phase is eliminated; meanwhile, through the combination of a homogenization process and an aging annealing process, the yield strength of the obtained high-entropy alloy at room temperature reaches 474 MPa-825 MPa, the tensile strength reaches 730 MPa-933 MPa, and the elongation rate can reach 15% -29%, so that the high-entropy alloy belongs to the high-entropy alloy with good comprehensive mechanical properties and has a good application prospect.

2. The homogenization parameter range is 910-1050 ℃, the heat preservation is carried out for 12-48 h, the alloy components can be uniformly distributed, and meanwhile, the alloy components have proper grain sizes, so that the elongation is improved, the uniformity of the subsequent aging annealing treatment phase formation is improved, and the integral strength is improved. Too low a homogenization temperature or too short a time results in insufficient homogenization of the components, while too high a homogenization temperature or too long a time results in too large grains, making it difficult to obtain a suitable grain size by cold rolling, resulting in a reduction in elongation and a weakening of the overall strength after the aging annealing treatment. On the basis of ensuring the homogenization of alloy components and the proper particle size, the comprehensive performance of the product can be regulated and controlled through an aging annealing process, the temperature range of the aging annealing process is 800-900 ℃, and the comprehensive mechanical performance of the product obtained by matching with the homogenization treatment process is the best when the time range is 0.5-1 h.

3. Mn is placed at the bottommost layer of the crucible during smelting, Fe, Ni and Cu are stacked layer by layer from bottom to top above the Mn according to the sequence of melting points from low to high, so that materials with low melting points can be preferentially and rapidly melted to cover the Mn, the evaporation capacity of the Mn is reduced to the maximum extent, and the Mn loss is reduced.

4. The argon gas reaction atmosphere of negative pressure not only can provide protective atmosphere, and argon gas can also arouse electric arc, helps the electric arc to smelt to go on, and the negative pressure can also form self-sealing effect, ensures that whole reaction environment is isolated with external, avoids the material oxidation.

5. And (3) cold rolling 80-90% of deformation on the basis of homogenizing annealing treatment, which is beneficial to refining crystal grains and improving the comprehensive mechanical property after aging annealing.

6. The parameters of homogenizing annealing are 1000 ℃, 12h and 85% of deformation of cold rolling, the parameters of aging annealing are that the strength of the product obtained when the product is kept at 800 ℃ for 1h is the highest, the yield strength at room temperature is 825MPa, the tensile strength is 933MPa, and the elongation at break is 15%; the parameters of homogenizing annealing are 1000 ℃, 12h and 85% of cold rolling deformation, the parameters of aging annealing are that the elongation of the product is highest when the temperature is kept at 850 ℃ for 1h, the yield strength at room temperature is 474MPa, the tensile strength is 730MPa, and the elongation at break is 29%.

7. After homogenization and aging annealing, the steel is rapidly cooled in a water-cooling quenching mode, so that the precipitation of brittle phases and compounds can be further inhibited, and the reduction of comprehensive mechanical properties can be further avoided.

Drawings

FIG. 1 is a graph comparing the stress-strain relationship in tensile tests for precipitation-strengthened high-entropy alloys without the tendency to precipitate the sigma phase prepared in examples 1 and 2;

FIG. 2 is an XRD diffractogram of the precipitation-strengthened high-entropy alloy having no tendency to precipitate the sigma phase prepared in example 1;

FIG. 3 is a room temperature tensile fracture morphology map of the precipitation-strengthened high-entropy alloy without the tendency of sigma phase precipitation prepared in example 1, wherein (a) is a fracture map, and (b) is an enlarged view of the fracture morphology;

fig. 4 is an SE SEM image of the precipitation-strengthened high-entropy alloy having no tendency to precipitate the σ phase, which was obtained in example 1, wherein (a) is an SE SEM image at 0.5h, and (b) is an SE SEM image at 1 h.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.