Alloying-method-based refined chromium-iron-cobalt-nickel-based high-entropy alloy crystal grain and preparation method thereof
阅读说明：本技术 基于合金化法细化铬铁钴镍基高熵合金晶粒及制备方法 (Alloying-method-based refined chromium-iron-cobalt-nickel-based high-entropy alloy crystal grain and preparation method thereof ) 是由 刘鑫旺 谢伦杰 刘磊 蒋文明 樊自田 于 2020-06-30 设计创作，主要内容包括：本发明属于金属材料领域,并具体公开了基于合金化法细化铬铁钴镍基高熵合金晶粒及其制备方法。该高熵合金晶粒由摩尔量之比为<Image he="110" wi="161" file="DDA0002563012530000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image><Image he="111" wi="523" file="DDA0002563012530000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>x的铬、铁、钴、镍以及细化元素组成,其中细化元素为碳、钛或铌,x的取值为2～7。本发明提供的基于合金化法细化铬铁钴镍基高熵合金晶粒由Cr、Co、Fe、Ni四种元素及细化元素(C、Ti或Nb)组成,基体为面心立方结构,其强度较基体CrCoFeNi高熵合金提升超过一倍,屈服强度≥350MPa,抗拉强度≥650Mpa,塑性应变≥35％,展现了极好的塑性强度结合较高的强度,并且具有各向同性的特点。(The invention belongs to the field of metal materials, and particularly discloses a high-entropy alloy grain of chromium, iron, cobalt and nickel base refined based on an alloying method and a preparation method thereof. The ratio of the molar weight of the high-entropy alloy grains is The material comprises x and refined elements, wherein the refined elements are carbon, titanium or niobium, and the value of x is 2-7. The high-entropy alloy grain of the invention consists of four elements of Cr, Co, Fe and Ni and refining element (C, Ti or Nb) based on alloying method refinement, the matrix is of face-centered cubic structure, the strength of the high-entropy alloy grain is improved by more than one time compared with the matrix CrCoFeNi high-entropy alloy, the yield strength is more than or equal to 350MPa, the tensile strength is more than or equal to 650MPa, and the plastic stress isThe transformation ratio is more than or equal to 35 percent, the excellent plastic strength is shown, the higher strength is combined, and the isotropy is realized.)
1. An alloying method based refined chromium-iron-cobalt-nickel-based high-entropy alloy grain is characterized in that the high-entropy alloy grain consists of the following components in molar ratio
2. The alloying-based refined CrFeCoNi-based high-entropy alloy grain of claim 1, wherein when the refining element is carbon, the value of x is 2-3; when the refining element is titanium, the value of x is 5-7; and when the refining element is niobium, the value of x is 4-6.
3. A preparation method for refining Cr-Fe-Co-Ni-based high-entropy alloy grains based on an alloying method is characterized by comprising the following steps:
s1 the molar weight ratio isSequentially putting the chromium, the iron, the cobalt, the nickel and the refining elements of x into the reactor from low to high in melting point order, so as to ensure that the elements with the lowest melting point are arranged at the lowest part, wherein the refining elements are carbon, titanium or niobium, and the value of x is 2-7;
s2, carrying out arc melting in an argon atmosphere, keeping stirring in the melting process to uniformly mix the raw materials, and cooling to obtain a prefabricated ingot;
s3, performing drop casting on the precast ingot to obtain the refined Cr-Fe-Co-Ni-based high-entropy alloy grains based on the alloying method.
4. The alloying-method-based preparation method for refining the Cr-Fe-Co-Ni-based high-entropy alloy grains according to claim 3, wherein when the refining element is carbon, the value of x is 2-3; when the refining element is titanium, the value of x is 5-7; and when the refining element is niobium, the value of x is 4-6.
5. The preparation method for refining Cr-Fe-Co-Ni-based high-entropy alloy grains based on alloying method as claimed in claim 3, wherein when the refining element is carbon, it is added in the form of Cr carbide powder and embedded in other metals.
6. The preparation method for refining the Cr-Fe-Co-Ni-based high-entropy alloy grains based on the alloying method as claimed in claim 3, wherein in step S2, the maximum smelting current is not more than 600A, the single smelting time is not less than 2 minutes, and the smelting times are not less than 5 times.
7. The method for preparing the cr-fe-co-ni-based high-entropy alloy grains refined based on the alloying method as claimed in claim 3, wherein in step S2, a transverse eddy magnetic field is applied during smelting, and then the raw materials are uniformly mixed by electromagnetic stirring, wherein the current intensity of the transverse eddy magnetic field is not more than 20A.
8. The method for preparing the Cr-Fe-Co-Ni-based high-entropy alloy grain refined based on the alloying method as claimed in claim 3, wherein in step S2, the melting is performed by using a non-consumable high-vacuum electric arc furnace.
9. The method for preparing the cr-fe-co-ni-based high-entropy alloy grain refined based on the alloying method as claimed in claim 3, wherein the maximum current at the time of drop casting is not more than 1000A at step S3.
10. The method for preparing the cr-fe-co-ni-based high-entropy alloy grains refined based on the alloying method as defined in any one of claims 3 to 9, wherein in step S3, a copper mold, a steel mold, or an oxide mold is used for drop casting.
Technical Field
The invention belongs to the field of metal materials, and particularly relates to a chromium-iron-cobalt-nickel-based high-entropy alloy grain refined based on an alloying method and a preparation method thereof.
Background
The high-entropy alloy is a novel alloy design concept which is provided by Taiwan scholars in 20 th century and 90 s in advance, is different from the traditional alloy, greatly enriches the research content of alloy materials, and is also called multi-principal-element high-entropy alloy because the mole percentage of each alloy element atom in the alloy is required to be more than 5%.
At present, the main research in the prior art is the preparation method, microstructure, performance and influence of elements on the alloy structure and mechanical performance, the change of the structure and performance under heat treatment, and the like of the high-entropy alloy. However, in general, the current research on high-entropy alloys is still in the preliminary stage.
Ferrochromium cobalt nickel high-entropy alloy has excellent plasticity, but cast alloy thereof consists of coarse columnar crystals, so that the strength is low and obvious anisotropy exists, and the practical application of the ferrochromium cobalt nickel high-entropy alloy as a structural material is hindered.
Disclosure of Invention
Aiming at the defects and/or improvement requirements of the prior art, the invention provides an alloying-based refined chromium-iron-cobalt-nickel-based high-entropy alloy grain and a preparation method thereof, wherein the high-entropy alloy grain is composed of four elements of Cr, Co, Fe and Ni and a refining element (C, Ti or Nb), a matrix is of a face-centered cubic structure, the strength of the high-entropy alloy grain is improved by more than one time compared with that of a matrix CrCoFeNi high-entropy alloy, the yield strength is more than or equal to 350MPa, the tensile strength is more than or equal to 650MPa, and the plastic strain is more than or equal to 35%.
In order to achieve the above object, according to one aspect of the present invention, there is provided an alloying-based method for refining ferrochromium-cobalt-nickel-based alloyEntropy alloy grains having a molar mass ratio of The alloy consists of chromium, iron, cobalt, nickel and refining elements, wherein the refining elements are carbon, titanium or niobium, and the value of x is 2-7.
Preferably, when the refining element is carbon, the value of x is 2-3; when the refining element is titanium, the value of x is 5-7; and when the refining element is niobium, the value of x is 4-6.
According to another aspect of the invention, a preparation method for refining Cr-Fe-Co-Ni-based high-entropy alloy grains based on an alloying method is provided, and the method comprises the following steps:
s1 the molar weight ratio is
s2, carrying out arc melting in an argon atmosphere, keeping stirring in the melting process to uniformly mix the raw materials, and cooling to obtain a prefabricated ingot;
s3, performing drop casting on the precast ingot to obtain the refined Cr-Fe-Co-Ni-based high-entropy alloy grains based on the alloying method.
Preferably, when the refining element is carbon, the value of x is 2-3; when the refining element is titanium, the value of x is 5-7; and when the refining element is niobium, the value of x is 4-6.
As a further preference, when the refining element is carbon, it is added in the form of a chromium carbide powder and embedded in the other metal.
More preferably, in the step S2, the maximum smelting current is not more than 600A, the single smelting time is not less than 2 minutes, and the smelting times are not less than 5 times.
More preferably, in step S2, a transverse eddy magnetic field is applied during melting, and the raw materials are mixed uniformly by electromagnetic stirring, wherein the current intensity of the transverse eddy magnetic field is not more than 20A.
Further preferably, in step S2, the smelting is performed in a non-consumable high vacuum arc furnace.
Further preferably, in step S3, the maximum current at the time of drip casting does not exceed 1000A.
Further preferably, in step S3, a copper mold, a steel mold, or an oxide mold is used for the drop casting.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. the invention provides a Cr-Fe-Co-Ni-based high-entropy alloy grain refined based on an alloying method, which consists of four elements of Cr, Co, Fe and Ni and a refining element (C, Ti or Nb), wherein a matrix is of a face-centered cubic structure, the strength of the alloy grain is improved by more than one time compared with that of a matrix CrCoFeNi high-entropy alloy, the yield strength is more than or equal to 350MPa, the tensile strength is more than or equal to 650MPa, and the plastic strain is more than or equal to 35 percent;
2. meanwhile, in the preparation method for refining the Cr-Fe-Co-Ni-based high-entropy alloy grains based on the alloying method, the distribution of matrix metal elements can be more uniform by adopting an electric arc melting and stirring mode, so that the obtained structure grains are fine and uniform and the segregation is reduced, and the comprehensive performance of the high-entropy alloy grains is effectively improved;
3. in addition, by optimizing various parameters in the preparation process, the invention can increase the tensile strength and keep higher plasticity while refining the Cr-Fe-Co-Ni-based high-entropy alloy grains.
Drawings
FIG. 1 is an SEM image of a (CrFeCoNi) -3 at.% C high entropy alloy made by example 1 of the present invention;
FIG. 2 is an SEM image of a (CrFeCoNi) -5 at.% Nb high entropy alloy made by example 2 of this invention;
FIG. 3 is an SEM image of a (CrFeCoNi) -5 at.% Ti high entropy alloy made by example 3 of this invention.
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.
The embodiment of the invention provides an alloying method based refined chromium-iron-cobalt-nickel-based high-entropy alloy grain, and the high-entropy alloy grain comprises the following components in molar ratio
further, when the refining element is carbon, the value of x is 2-3; when the refining element is titanium, the value of x is 5-7; when the refining element is niobium, the value of x is 4-6, so that the tensile strength is increased and higher plasticity is kept while the Cr-Fe-Co-Ni-based high-entropy alloy grains are refined.
According to another aspect of the invention, a preparation method for refining Cr-Fe-Co-Ni-based high-entropy alloy grains based on an alloying method is provided, and the method comprises the following steps:
s1 the molar weight ratio isThe chromium, iron, cobalt, nickel and refining elements are selected fromSequentially putting the melting points into a water-cooled metal copper crucible from low to high, thereby ensuring that the element with the lowest melting point is arranged at the lowest part and the element with the highest melting point is arranged at the top, wherein the refining element is carbon, titanium or niobium, and the value of x is 2-7;
s2 vacuumizing to less than 2 × 10-2Pa, then argon gas was introduced to about 5 × 104Pa, repeating the operation for 2 times, and smelting a pure titanium block to absorb residual air before arc striking so as to obtain a high-purity smelting atmosphere; then arc melting is carried out under argon atmosphere, stirring is kept during the melting process to ensure that the raw materials are uniformly mixed, and a prefabricated ingot is obtained after cooling;
s3 drop casting the precast ingot to obtain the refined Cr-Fe-Co-Ni-based high-entropy alloy grains based on the alloying method.
Further, when the refining element is carbon, the value of x is 2-3; when the refining element is titanium, the value of x is 5-7; when the refining element is niobium, the value of x is 4-6, so that the tensile strength is increased and higher plasticity is kept while the Cr-Fe-Co-Ni-based high-entropy alloy grains are refined. When the refining element is carbon, the refining element is added in the form of chromium carbide powder and is embedded in other metals to prevent the refining element from being blown away by airflow.
Further, in step S2, a non-consumable high vacuum arc furnace is used for melting, the maximum melting current during melting does not exceed 600A, so as to avoid burning loss of elements; the single smelting time is not less than 2 minutes, the smelting times are not less than 5 times, and the components are uniformly mixed; and a transverse eddy magnetic field is applied during smelting, so that the raw materials are uniformly mixed through electromagnetic stirring, and meanwhile, the current intensity of the transverse eddy magnetic field is not more than 20A, and the raw materials are prevented from splashing.
Further, in step S3, the maximum current during drop casting does not exceed 1000A; the drop casting process uses a copper mold casting mold, a steel mold casting mold or an oxide casting mold, the types of the mold materials are diverse, small ingots (parts) with various required sizes can be prepared, and the drop casting process has the characteristics of convenience, rapidness and easiness in implementation.
The invention is further illustrated by the following examples.
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