WO2021261609A1 - Alliage à entropie élevée et procédé de traitement thermique de celui-ci - Google Patents

Alliage à entropie élevée et procédé de traitement thermique de celui-ci Download PDF

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WO2021261609A1
WO2021261609A1 PCT/KR2020/008188 KR2020008188W WO2021261609A1 WO 2021261609 A1 WO2021261609 A1 WO 2021261609A1 KR 2020008188 W KR2020008188 W KR 2020008188W WO 2021261609 A1 WO2021261609 A1 WO 2021261609A1
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phase
entropy alloy
heat treatment
metal
high entropy
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PCT/KR2020/008188
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English (en)
Korean (ko)
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신현권
강남석
오진목
최진혁
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엘지전자 주식회사
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Priority to US18/011,915 priority Critical patent/US20230304111A1/en
Priority to PCT/KR2020/008188 priority patent/WO2021261609A1/fr
Priority to DE112020007343.2T priority patent/DE112020007343T5/de
Publication of WO2021261609A1 publication Critical patent/WO2021261609A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1031—Alloys containing non-metals starting from gaseous compounds or vapours of at least one of the constituents
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C22C30/02—Alloys containing less than 50% by weight of each constituent containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/24—Nitriding

Definitions

  • the present embodiment relates to a high entropy alloy and a heat treatment method thereof, and more particularly, to a high entropy alloy having an improved structure and process and a heat treatment method thereof.
  • a high entropy alloy is an alloy having a single-phase structure of a face-centered cubic structure (FCC) or a body-centered cubic structure (BCC) having a high mixed entropy by including a plurality of elements in a predetermined amount or more.
  • High entropy alloys having a face-centered cubic structure mainly include titanium (Ti), vanadium (V), zirconium, niobium (Nb), molybdenum (Mo), hafnium (Hf), tantalum (Ta), tungsten (W), etc. It has excellent high-temperature strength and is used in the aerospace field, engine gas turbine, and the like.
  • a high-entropy alloy having a body-centered cubic structure mainly contains iron (Fe), manganese (Mn), chromium (Cr), nickel (Ni), cobalt (Co), etc., and has excellent cryogenic strength and toughness and low thermal conductivity It is used in liquefied natural gas (LNG) storage tanks and polar structures.
  • LNG liquefied natural gas
  • the high-entropy alloy having such a body-centered cubic structure has high strength and high toughness, so it is being applied in various fields, but it is more expensive than general alloy materials. Accordingly, research on high-entropy alloys in which copper (Cu) and aluminum (Al) are added instead of nickel and cobalt, which are expensive, are being studied.
  • Aluminum is a representative lightweight element and can be applied to various fields to improve the efficiency of equipment. Copper and iron exhibit a metastable liquid phase separate (MLPS) phenomenon, so a copper-rich phase and an iron-rich phase are mixed on the matrix. In each phase, the unique properties of individual elements are mixed to exhibit complex properties, and excellent strength and excellent elongation properties can be simultaneously realized by using the excellent mechanical properties of iron and the ductility of copper. However, a treatment for improving wear resistance is required because a phenomenon in which abrasion resistance is deteriorated due to the influence of copper occurs.
  • An object of the present disclosure is to provide a high entropy alloy having excellent ductility, strength, hardness and wear resistance and a heat treatment method thereof.
  • the present disclosure provides a high-entropy alloy capable of improving strength, hardness and wear resistance while maintaining excellent ductility by a second phase by selectively forming a reinforcing compound in a first phase having a relatively high strength, and
  • An object of the present invention is to provide a heat treatment method thereof.
  • the present disclosure provides a high-entropy alloy including an iron-rich phase and a copper-rich phase and selectively forming a reinforcing compound in the iron-rich phase to have excellent ductility, strength, hardness and wear resistance, and a heat treatment method thereof .
  • the high entropy alloy according to the present embodiment includes first and second phases each including iron and copper, and a first metal other than iron and copper, but having different compositions.
  • a reinforcing compound formed by chemically bonding the first metal and the non-metal is selectively provided on the first phase.
  • the reinforcing compound may be provided in the form of internal precipitates located inside the first phase.
  • the reinforcing compound comprises: a first reinforcing precipitate located near the surface of the first phase and having a first size; and a second reinforcing precipitate located in an inner portion of the first phase and having a second size greater than the first size; may include
  • the strength or hardness of the first phase may be greater than the strength or hardness of the second phase, and the reinforcing compound may not be provided on the second phase.
  • the hardness of the first phase may be more than twice the hardness of the second phase.
  • the first phase may be an iron-rich phase
  • the second phase may be a copper-rich phase
  • the first metal may include aluminum.
  • the non-metal may have a solubility in the first phase that is higher than a solubility in the second phase, and a diffusion rate in the first phase is greater than a diffusion rate in the second phase.
  • the non-metal may include nitrogen or oxygen.
  • the reinforcing compound may be composed of aluminum nitride (AlN).
  • the high-entropy alloy heat treatment method prepares a high-entropy alloy material including a first phase and a second phase each including iron and copper, and a first metal other than iron and copper, but having different compositions to, preparatory stage; and a selective strengthening step of selectively forming a strengthening compound on the first phase by chemically reacting the first metal included in the first phase with a non-metal by performing a heat treatment using a non-metal.
  • the first metal may include aluminum.
  • the non-metal may have a solubility in the first phase that is higher than a solubility in the second phase, and a diffusion rate in the first phase is greater than a diffusion rate in the second phase. Since the non-metal contains nitrogen or oxygen, the selective strengthening step may be performed by a nitridation treatment or an oxidation treatment.
  • the selective strengthening step may be performed at a heat treatment temperature of 500 °C to 1500 °C.
  • the selective strengthening step may be performed by nitridation using a reaction gas containing ammonia gas and hydrogen gas, and the first metal may include aluminum, so that the strengthening compound may be composed of aluminum nitride (AlN).
  • the hydrogen gas may be included in an amount of 10 vol% or less with respect to 100 vol% of the total reaction gas.
  • the first phase may be an iron-rich phase
  • the second phase may be a copper-rich phase
  • the reinforcing compound may be provided in the form of internal precipitates located inside the first phase.
  • the strength or hardness of the first phase may be greater than the strength or hardness of the second phase, and the reinforcing compound may not be provided on the second phase.
  • the first phase having relatively high strength and hardness is selectively provided with the reinforcing compound, and the second phase having relatively excellent ductility is not provided with the reinforcing compound, which has relatively high strength.
  • the strength of the first phase can be greatly improved.
  • the reinforcing compound is formed on the first phase, which is a part of the high-entropy alloy, the amount of change is small, so that the distortion phenomenon does not occur, and thus it can be applied to casting parts requiring precision.
  • the heat treatment method of the high entropy alloy according to the present embodiment it is possible to form a high entropy alloy in which the strengthening compound is selectively formed in the first phase by a simple process that specifically defines the process conditions of the selective strengthening step. And by applying the heat treatment method of the high-entropy alloy according to the present embodiment to various materials or compositions, it is possible to easily manufacture a high-entropy alloy having desired properties. Thereby, it is possible to manufacture a high-entropy alloy having excellent ductility, strength, hardness and wear resistance through a simple process.
  • FIG. 1 is a diagram schematically showing the structure of a high-entropy alloy according to an embodiment of the present invention.
  • FIG. 2 is a flowchart illustrating a heat treatment method of a high entropy alloy according to the present embodiment.
  • 3A and 3B are cross-sectional views illustrating a heat treatment method of the high entropy alloy shown in FIG. 2 .
  • FIG. 4 is a view for explaining the optimum heat treatment temperature of the heat treatment method of a high entropy alloy according to an embodiment of the present invention.
  • FIG. 5 is a view for explaining the principle of forming a strengthening compound according to the diffusion rate in the heat treatment method of a high entropy alloy according to an embodiment of the present invention.
  • FE-SEM field emission scanning electron microscope
  • ESD energy dispersive spectroscopy
  • FIG. 7 is an optical micrograph of a cross-section of the high entropy alloy according to Example 1.
  • Example 8 is an optical micrograph of a cross-section of the high-entropy alloy according to Example 2.
  • FIG. 9 is an optical micrograph of a cross-section of the high-entropy alloy according to Example 3.
  • FIG. 9 is an optical micrograph of a cross-section of the high-entropy alloy according to Example 3.
  • Example 10 is a FE-SEM / EDS photograph of the high entropy alloy according to Example 1.
  • Example 11 is a FE-SEM/EDS photograph of the high entropy alloy according to Example 2.
  • FIG. 13 is a graph showing the nitrogen content according to the depth from the surface in the high entropy alloy material (comparative example) and the high entropy alloy according to Examples 1 to 3;
  • Example 14 is a graph showing the content of each element according to the depth from the surface in the high entropy alloy according to Example 1.
  • Example 15 is a graph showing the content of each element according to the depth from the surface in the high entropy alloy according to Example 2.
  • 16 is a graph showing the content of each element according to the depth from the surface in the high entropy alloy according to Example 3.
  • 17 is a graph showing the hardness of the high-entropy alloy material (comparative example) and the high-entropy alloy according to Examples 1 to 3;
  • Example 19 is an optical micrograph of a cross-section of the high-entropy alloy according to Example 2.
  • FIG. 1 is a diagram schematically showing the structure of a high entropy alloy 10 according to an embodiment of the present invention.
  • 1 shows various examples of the structure of the high entropy alloy 10 according to the present embodiment.
  • each of the first phase 20 and the second phase 20 is provided one by one and has a rectangular shape having the same size as each other. that was shown.
  • the present invention is not limited thereto, and in the present embodiment, the first phase 20 and the second phase 30 included in the high entropy alloy 10 may have different sizes.
  • the high entropy alloy 10 may include a plurality of the first phase 20 and/or the second phase 30 , and the size and shape thereof may be variously modified.
  • the first phase 20 and the second phase 30 may have an irregular shape and a mixed shape with each other.
  • the high-entropy alloy 10 is a term used to distinguish it from a low-entropy alloy, and may collectively refer to an alloy having an entropy of a certain level or higher.
  • the high-entropy alloy 10 has an entropy of 1.5R or more and generally has an entropy of 1.0R or more, as well as an alloy called a high entropy alloy (high entropy alloy). ) may include an alloy called That is, the high-entropy alloy 10 according to the present embodiment may have an entropy of 1.0R or more.
  • the high entropy alloy 10 includes a first phase 20 and a first metal having different compositions including iron and copper, and a first metal that is a metal other than iron and copper, respectively. It includes two phases (30).
  • the reinforcing compound 22 formed by chemically bonding the first metal and the non-metal may be selectively provided on the first phase 20 , but may not be provided on the second phase 30 .
  • the high-entropy alloy 10 may be composed of a dual phase including a first phase 20 and a second phase 20 having different materials or compositions.
  • the first phase 20 and the second phase 30 may be an alloy containing iron and copper
  • the first phase 20 may be an iron-rich phase
  • the second phase 30 may be a copper- may be lychee. Since iron and copper exhibit metastable liquid phase separation, the iron-rich first phase 20 and the copper-rich second phase 30 are mixed in the high entropy alloy 10 .
  • the first metal included in each of the first phase 20 and the second phase 30 may include aluminum, and is combined with the first metal in the first phase 20 to form the reinforcing compound 22 .
  • the base metal may be nitrogen or oxygen.
  • the reinforcing compound 22 may include aluminum nitride (AlN) or aluminum oxide (AlOx). This will be described in more detail later.
  • the iron-rich phase may mean a phase having the highest iron content (eg, at%) among a plurality of materials (eg, elements) constituting the same, and the copper-rich phase is a plurality of materials constituting the same. It may refer to a phase having the highest copper content (eg, at%) among (eg, elements).
  • a phase having a relatively high iron content or a relatively low copper content is selected as an iron-rich phase, a relatively low iron content, or It can be said that the copper-rich phase has a relatively high copper content. That is, the iron-rich phase and the copper-rich phase may be a relative concept rather than an absolute concept.
  • the high-entropy alloy according to the present embodiment may further include at least one of manganese, chromium, nickel, carbon, silicon, and phosphorus in consideration of various characteristics.
  • it may further include a melting point lowering element (melting point lowering material) for lowering the melting point of the high entropy alloy, the melting point lowering element may include carbon, silicon, phosphorus, manganese, and the like.
  • Iron is inexpensive, has excellent strength and ductility, and the strength and hardness vary greatly depending on the phase structure, so it can be easily adjusted so that the high-entropy alloy has the desired properties.
  • Copper has a low melting point and has good electrical and thermal conductivity.
  • copper is not mixed with iron and forms a double-phase structure of an iron-rich phase and a copper-rich phase, which is suitable for forming a high-entropy alloy capable of improving both iron and copper properties.
  • the high-entropy alloy according to the present embodiment contains iron and copper that do not mix well with each other, unless other metals are included, they do not mix with each other, making it difficult to form an alloy. Accordingly, in order to prevent phase separation of iron and copper, an alloy including aluminum, manganese, nickel, etc. having a predetermined or higher solubility in each of iron and copper may be formed. Accordingly, the high-entropy alloy has an iron-rich phase and a copper-rich phase, but the ratio of the iron-rich phase and the copper-rich phase may vary depending on the content of iron and copper.
  • the high entropy alloy according to the present embodiment has a dual-phase structure including an iron-rich phase and a copper-rich phase, but the iron-rich phase is included in a larger volume ratio than the copper-rich phase, so that the main phase (main phase) ) and the copper-rich phase may be partially present. Then, segregation can be prevented, so that the high-entropy alloy can have a uniform composition with high strength, workability, castability, and wettability.
  • aluminum is a lightweight element (hard material) and is mixed with iron as a low melting point element (low melting point material) to form a body-centered cubic structure.
  • Aluminum can improve hardness, abrasion resistance, strength, etc. while reducing ductility.
  • manganese When manganese is included in iron, strength and ductility can be improved at the same time.
  • it may be selectively nitridized or oxidized in the first phase 20 to selectively form the reinforcing compound 22 . This will be described in more detail later.
  • Manganese has a lower melting point than iron and can act as a kind of melting point lowering element that lowers the melting point of a high entropy alloy.
  • the fluidity and castability of the high entropy alloy can be improved.
  • chromium When chromium is included in iron, it is possible to additionally improve corrosion resistance by forming a chromium oxide film on iron or iron-rich. Chromium may or may not be included in the high entropy alloy. Nickel increases the solubility of copper in the iron-rich phase, thereby reducing the copper content in the high entropy alloy as a whole. Accordingly, it is possible to reduce the material cost by lowering the relatively expensive copper content and increasing the relatively inexpensive iron content. In addition, it is possible to lower the melting temperature in the process of manufacturing a high entropy alloy and improve corrosion resistance.
  • silicon, carbon, phosphorus, manganese, etc. may lower the melting point of the high-entropy alloy to have excellent fluidity and wettability, and low high-temperature viscosity during the manufacturing process of the high-entropy alloy.
  • castability can be improved.
  • silicon is included as a low melting point element
  • castability can be improved and corrosion resistance can be improved by forming an oxide.
  • carbon is included as a low-melting-point element
  • the melting point can be effectively lowered.
  • Phosphorus is included as a low melting point element, and the melting point can be effectively lowered even with a small amount.
  • the high entropy alloy material excluding the non-metal (nitrogen or oxygen) included in the reinforcing compound 22 is 15 to 80 at% iron, 1 to 30 at% copper, 5 to 20 at% aluminum, 0-20 at% nickel, 0-30 at% (eg 0.1-30 at%, eg 5-30 at%) manganese, 0-15 at% (eg For example, 2 to 15 at%) of chromium, 0 to 5 at% (eg, 3 to 5 at%) of carbon, 0 to 2 at% of silicon (eg, 1 to 2 at%), 0 to 2 at% (eg, 0 to 1 at%) of phosphorus, other elements, or unavoidable impurities may be included.
  • This range is limited to improve the ductility, strength, hardness, wear resistance, castability, etc. of the high entropy alloy.
  • the present invention is not limited to the elements and contents described above. Accordingly, elements or materials other than the above-described elements or materials may be further included, and the content of each element or material may be variously modified in consideration of the characteristics of a desired high-entropy alloy.
  • the first phase 20 is composed of an iron-rich phase containing more iron than copper and may have greater strength, hardness, and abrasion resistance than the second phase 30 , and the second phase 30 is greater than iron. It may have excellent ductility as it is composed of a copper-rich phase containing a lot of copper.
  • the first phase 20 having a relatively large strength or hardness may optionally further include a reinforcing compound 22 to selectively further strengthen the first phase 20 having a large strength or hardness.
  • the hardness of the first phase 20 may have a value greater than or equal to twice the hardness of the second phase 30 . Thereby, the strength, hardness, and abrasion resistance of the first phase 20 can be effectively improved.
  • the reinforcing compound 22 may not be provided in the second phase 30 . Accordingly, while maintaining the excellent ductility of the second phase 30 as it is, a decrease in strength and abrasion resistance caused by the second phase 30 can be prevented by selectively strengthening the first phase 20 .
  • the second phase 30 may be provided with the reinforcing compound 22 . Even in this case, the amount of the reinforcing compound 22 provided in the second phase 30 is provided in the first phase 20 . It may be smaller than the amount of the reinforcing compound 22, and in fact, it may be provided in a very small amount.
  • the selective provision of the reinforcing compound 22 in the first phase 20 specifies the heat treatment of the high entropy alloy 10 in consideration of the characteristic difference between the first phase 20 and the second phase 30 . Because it was carried out under the conditions. This will be described in more detail later in the heat treatment method of the high entropy alloy 10 .
  • aluminum may be used as the first metal constituting the reinforcing compound 22, and nitrogen or oxygen may be used as the non-metal.
  • selective chemical treatment eg, nitridation or oxidation treatment
  • aluminum is an element that is selectively nitridated or oxidized in the first phase 10 composed of the iron-rich phase and is not nitridized or oxidized in the second phase 20 composed of the copper-rich phase.
  • the solubility in the first phase 20 is greater than the solubility in the second phase 30 and the diffusion rate in the first phase 20 is greater than the diffusion rate in the second phase 30 It can be used, but nitrogen or oxygen is an element that satisfies these properties. Accordingly, more nitrogen or oxygen is provided in the first phase 20 and diffuses faster, so that the reinforcing compound 22 can be more easily formed in the first phase 20 .
  • the reinforcing compound 22 may be formed of an oxide or a nitride. More specifically, the reinforcing compound 22 may be composed of aluminum nitride or aluminum oxide. The reinforcing compound 22 may be made of ceramic to effectively improve strength, hardness, and abrasion resistance. As an example, when the reinforcing compound 22 is made of aluminum nitride, the reinforcing compound 22 is selectively formed in the first phase 20 stably while minimizing the change in undesired properties by nitriding to improve strength, hardness and Abrasion resistance can be improved.
  • the reinforcing compound 22 may have a form of a plurality of internal precipitates scattered while having a uniform and even distribution and size in the interior of the first phase 20 .
  • the strength and hardness of the first phase 20 can be effectively improved and maintained on the reinforcing side. That is, when the reinforcing compound 22 is uniformly and evenly formed to the deep inside of the first phase 20 by diffusing oxygen or nitrogen to the deep inside of the first phase 20, the high entropy alloy 10 Abrasion resistance can be greatly improved.
  • the reinforcing compound 22 when the reinforcing compound 22 is located on the surface or inside the thin depth of the first phase 20 , a portion not provided with the reinforcing compound 22 is exposed due to wear, so it may be difficult to expect improvement in abrasion resistance.
  • the present invention is not limited thereto, and the reinforcing compound 22 may be formed in various forms in the first phase 20 .
  • the reinforcing compound 22 is located near the surface of the first phase 20 and a first reinforcing precipitate having a first size (eg, a first average size) ( 22a), and a second reinforcing precipitate 22b positioned in the inner portion of the first phase 20 and having a second size (eg, a first average size) larger than the first size.
  • a first size eg, a first average size
  • a second reinforcing precipitate 22b positioned in the inner portion of the first phase 20 and having a second size (eg, a first average size) larger than the first size.
  • the reinforcing compound 22 may be partially located near the surface of the first phase 20 .
  • the reinforcing compound 22 is also formed in the inner portion, but the amount or number formed in the inner portion is small, so that the reinforcing compound 22 may be more densely formed near the surface than in the inner portion of the first phase 20 have. This is due to the process conditions in the heat treatment method for forming the reinforcing compound 22, and the difference in the diffusion degree of the non-metal. Even in this case, the strengthening precipitates 22 are formed near the surface of the high entropy alloy 10 to improve the hardness and wear resistance of the high entropy alloy 10 in the vicinity of the surface.
  • the reinforcing compound 22 has a precipitation shape 221 having the form of an internal precipitate, and a layered form formed on the surface of the first phase 20 (eg, For example, it may include a layered shape 222 configured in the form of a film).
  • the reinforcing compound 22 includes the precipitation features 221 and the layered features 222 . It is possible. And in (d) of FIG. 1 , the layered shape part 222 is illustrated as being formed entirely on the surface of the first phase 20 , but as in FIG. 1(e), the layered shape part 222 is the first phase It may be partially formed on the surface of (20). And in (a) to (d) of FIG. 1 , it was exemplified that the additional compound layer 32 is not formed on the surface of the second phase 30 , but as in FIG. An additional compound layer 32 having a layered shape may be formed on the surface.
  • This additional compound layer 32 includes a metal and a non-metal (ie, nitrogen or oxygen) other than the first metal (ie, aluminum) among the metals included in the second phase 30 during the heat treatment to form the reinforcing compound 22 .
  • It may be a material formed by chemical bonding (eg, manganese nitride, etc.).
  • the additional compound 32 may be located only on the surface of the second phase without being formed in the form of internal precipitates.
  • the additional compound layer 32 may slightly improve hardness and abrasion resistance on the surface of the second phase 30 .
  • the additional compound layer 32 is partially formed on the surface of the second phase 30, but as in FIG. 1(e), the additional compound layer 32 is formed on the second phase 30 ) may be formed entirely on the surface of the
  • the reinforcing compound 22 and the additional compound layer 32 may be variously modified.
  • the reinforcing compound 22 may be provided in the form of internal precipitates dispersed inside or on the surface of the first phase 20 or in a layered shape.
  • the reinforcing compound 22 may have various shapes such as a spherical shape, a flake shape, a needle shape, an irregular shape, a layer shape, and the like.
  • the presence, shape, size, etc. of the strengthening compound 22 can be easily detected or discriminated by component analysis, micrograph, or the like.
  • the reinforcing compound 22 may have a size of 1 nm or more (eg, average size), and may have a size of 1 mm or less (eg, average size). This is because if the size or thickness of the reinforcing compound 22 is less than 1 nm, the effect of the reinforcing compound 22 may not be sufficient, and if the size or thickness of the reinforcing compound 22 exceeds 1 mm, brittleness may increase.
  • the size of the reinforcing compound 22 may mean the length of the major axis.
  • the size of the reinforcing compound 22 may mean the thickness of the layered shape.
  • the present invention is not limited thereto, and the size, shape, density, distribution, etc. of the reinforcing compound 22 may be variously modified.
  • the first phase 20 having relatively high strength and hardness in the high entropy alloy 10 including the first phase 20 and the second phase 30 having different compositions or properties is
  • the second phase 30 having the reinforcing compound 22 and having relatively excellent ductility does not include the reinforcing compound.
  • the strength, hardness and abrasion resistance of the single phase 20 can be greatly improved.
  • the high entropy alloy 10 may have excellent ductility, strength, hardness, and wear resistance.
  • the reinforcing compound 22 is formed only in a part of the high entropy alloy 10 (that is, the first phase 22), and the amount of change is small, distortion does not occur, so it can be applied to casting parts requiring precision. .
  • the high-entropy alloy 10 described above is a multi-composition alloy including a plurality of metals and including a first phase 20 and a second phase 30.
  • the multi-composition alloy is heat-treated as a whole under general conditions, the surface roughness is reduced. Even if an oxide film or a nitride film is formed on the surface, problems such as peeling may occur. Accordingly, the high-entropy alloy 10, which is a multicomponent alloy, must be heat-treated under specific process conditions (eg, selective strengthening heat treatment) so that the desired strengthening compound 22 is selectively formed only in the first phase 20 .
  • FIG. 2 is a flowchart illustrating a heat treatment method of the high entropy alloy 10 according to the present embodiment.
  • 3A and 3B are cross-sectional views illustrating a heat treatment method of the high entropy alloy 10 shown in FIG. 2 .
  • the heat treatment method of the high entropy alloy 10 according to the present embodiment will be described in more detail with reference to FIGS. 3A and 3B .
  • the manufacturing of the high-entropy alloy 10 shown in FIG. 1A is illustrated in FIGS. 3A and 3B , but the present invention is not limited thereto.
  • the heat treatment method of the high entropy alloy 10 includes a preparation step (ST10) of preparing the high entropy alloy material 10a and optionally the reinforcing compound 22 ) may include a selective strengthening step (ST20) to form.
  • the high-entropy alloy material 10a may include a first phase 20a and a second phase 30 each including iron, copper, and a first metal and having different compositions. have.
  • the selective strengthening step ST20 the first metal included in the first phase 20a may be chemically reacted with a non-metal to selectively form the strengthening compound 22 in the first phase 20a.
  • the first phase 20 in which the reinforcing compound 22 is provided may be formed by the selective reinforcing step ST20.
  • the first phase 20a and the high-entropy alloy material 10a have a first phase (preliminary first phase) before strengthening without the strengthening compound 22 because the selective strengthening step ST20 is not performed, respectively, and It may refer to a high-entropy alloy before strengthening, and the first phase 20 and the high-entropy alloy 10 are first phase and after strengthening after strengthening with a strengthening compound 22 by performing a selective strengthening step (ST20) It may mean a high entropy alloy.
  • a high-entropy alloy material 10a having a first phase 20a and a second phase 30 is prepared.
  • the first phase 20a and the second phase 30 may be an alloy including iron and copper
  • the first phase 20a may be an iron-rich phase
  • the second phase 30 may be a copper- may be lychee.
  • the first phase 20a or the second phase 30 may further include manganese, nickel, chromium, carbon, silicon, phosphorus, or the like.
  • the composition of the first phase 20a and the second phase 30 or the composition of the high entropy alloy material 10a may be variously modified.
  • the selective strengthening step ST20 heat treatment using a non-metal may be performed on the high entropy alloy material 10a.
  • the selective strengthening step (ST20) of performing a heat treatment using a non-metal the first metal included in the first phase 20 is chemically combined with the non-metal to form the strengthening compound 22, and the second phase ( The first metal included in 30) may not be chemically combined with a non-metal, so that the reinforcing compound 22 may not be formed.
  • the first metal may be aluminum.
  • the non-metal chemically bonded to the first metal has a higher solubility in the first phase 20 than the solubility in the second phase 30, and the diffusion rate in the first phase 20 is higher in the second phase (30). may be higher than the diffusion rate in Accordingly, during the heat treatment, the non-metal diffuses easily in the first phase 20 and is easily chemically combined with the first metal, thereby improving the possibility that the reinforcing compound is formed only in the first phase 20 .
  • the non-metal may be nitrogen or oxygen, and accordingly, the selective strengthening step ST20 may be performed as a nitridation treatment or an oxidation treatment.
  • the nonmetal chemically bonded to the first metal is nitrogen will be described as an example.
  • the solubility of nitrogen in iron is 250 ppm, which is much higher than the solubility of nitrogen in copper of 1 to 4 ppm. Accordingly, the solubility of nitrogen in the first phase 20 containing relatively more iron may be greater than the solubility of nitrogen in the second phase 30 containing relatively more copper.
  • the diffusion rate of nitrogen is proportional to the concentration of nitrogen, the diffusion rate of nitrogen in iron is faster than that in copper. Since the diffusion rate of nitrogen is the fastest in iron, nitrogen can be easily diffused, and in copper, a metal having a faster diffusion rate than that of nitrogen (ie, manganese) is provided, so that diffusion of nitrogen may not occur well. . Accordingly, in the first phase 20 containing a lot of iron, nitrogen can easily diffuse to form the reinforcing compound 22 , and in the second phase 30 containing a lot of copper, diffusion of nitrogen is inhibited to form the reinforcing compound (22) may not be formed or the reinforcing compound (22) may be formed in an amount less than that of the first phase (20).
  • the selective nitridation heat treatment may be performed using a nitrogen-containing gas including nitrogen at a heat treatment temperature higher than room temperature.
  • reaction gas used in the selective nitridation heat treatment may include a nitrogen-containing gas.
  • the reaction gas may use ammonia gas (eg, NH 3 ) as the nitrogen-containing gas, hydrogen gas (eg, single hydrogen gas, H 2 ) and/or single nitrogen gas (eg, N 2 ) ) may be further included.
  • Ammonia gas has a relatively low binding energy and can be easily dissociated into ions to stably provide nitrogen and also provide hydrogen.
  • the effect of hydrogen provided by ammonia gas is the same as or similar to the effect by hydrogen gas, which will be described later.
  • the reaction gas may provide an atmosphere suitable for the nitridation treatment or the nitridation reaction, including hydrogen gas forming a reducing atmosphere. That is, if hydrogen or hydrogen gas is not used in the selective nitridation heat treatment, the nitridation rate is very slow even if the nitridation reaction occurs, and iron nitride may be present during nitridation.
  • the nitridation driving force is very strong, causing a nitridation reaction with an unwanted metal to form an unwanted surface film, thereby preventing nitrogen from penetrating into the interior.
  • the nitridation rate is increased and the nitrogen potential is controlled to prevent or minimize the occurrence of undesirable nitrides or surface coatings.
  • it is possible to prevent or minimize the gas phase decomposition of ammonia gas by forming a condition that prevents the decomposition of ammonia gas in the gas phase to lower the reaction coefficient of ammonia gas decomposition.
  • ammonia gas can be decomposed only on the surface of the high entropy alloy material 10a, and the nitrogen decomposed on the surface in this way can effectively penetrate into the high entropy alloy material 10a. Accordingly, it is possible to evenly form the reinforcing compound 22 in the form of an internal precipitate to the deep inside while minimizing the occurrence of a surface film.
  • hydrogen gas may be included in an amount of 10 vol% or less (for example, 0.1 vol% or more, more specifically 1 vol% or more) with respect to 100 vol% of the total reaction gas. If hydrogen gas is included in less than 10 vol%, the nitridation rate may be lowered due to lack of ammonia gas, and in severe cases, the nitridation rate is very slow, and the strengthening compound 22 is generated even after a long time (eg, 10 hours) it may not be And when hydrogen gas is included in less than 0.1 vol% (for example, less than 1 vol%), the increase in the nitridation rate may not be sufficient, and an unwanted nitridation reaction with metals to form an undesired surface film causes nitrogen to be internally may impede penetration.
  • the present invention is not limited thereto, and the volume ratio of hydrogen gas may be variously modified.
  • the single nitrogen gas may be provided so that the reaction gas is supplied in a volume suitable for the selective nitridation heat treatment process, and in some cases, may also serve to additionally supply nitrogen. Accordingly, the selective nitriding heat treatment process may be stably performed.
  • the amount of a single nitrogen gas may be greater than each of the ammonia gas and the hydrogen gas, so that a stable process may be performed.
  • ammonia gas may be included in an amount of 5 to 20 vol% based on 100 vol% of the total sum of ammonia gas and a single nitrogen gas.
  • this is only an example of the volume ratio of ammonia gas for a stable process, and the present invention is not limited thereto.
  • the heat treatment temperature at which the selective nitriding heat treatment is performed in this embodiment has a range at which the strengthening compound 22 can be stably formed by thermodynamic calculation and kinetic calculation based on thermodynamic information (Gibbs free energy), in particular, nitrogen
  • thermodynamic information Gabbs free energy
  • nitrogen there is an optimal range for forming the reinforcing compound 22 to the deep inside of the first phase 20a by diffusing to the deep inside. That is, there is a certain temperature range by thermodynamic calculation for the selective nitriding heat treatment, and the formation of a surface film is suppressed through the calculation of the diffusion rate of nitrogen and metal elements, and the formation of precipitates in the interior of the first phase 20a
  • There is a certain temperature range for forming the reinforcing compound 22 There is a certain temperature range for forming the reinforcing compound 22 .
  • the nitriding heat treatment must be performed under process conditions such as a temperature that satisfies all of these temperature ranges, preventing or minimizing the formation of the reinforcing compound 22 in a layered form on the surface of the first phase 20a while preventing or minimizing the inside of the first phase 20a , a specific element (ie, the first metal) may be selectively nitrided to form the reinforced compound 22 in the form of an internal precipitate. According to this, strength, hardness and abrasion resistance can be effectively improved. This will be described with reference to FIG. 4 .
  • FIG 4 is a view for explaining the optimum heat treatment temperature in the heat treatment method (for example, selective nitriding heat treatment) of the high entropy alloy 10 according to an embodiment of the present invention.
  • the optimum heat treatment temperature may be limited to a temperature satisfying the following three conditions.
  • gas phase decomposition of the reaction gas eg, ammonia gas, which is a nitrogen-containing gas
  • gas phase decomposition of the reaction gas eg, ammonia gas, which is a nitrogen-containing gas
  • a temperature for example, a temperature below the first temperature (T1) at which the diffusion rate of metal atoms is low to prevent or delay the formation of an unwanted surface film by reacting the metal and nitrogen by external diffusion of the unwanted metal ) should be heat-treated.
  • the selective nitridation heat treatment should be performed at a certain temperature or higher (for example, the second temperature T2 or higher) so that the nitrogen diffusion rate in the first phase 20 has a value of a certain level or higher, and the reaction gas (for example, the second temperature T2 or higher) , should be carried out at a temperature below a temperature at which the concentration of ammonia gas, which is a gas containing nitrogen, is sufficiently constant (for example, below the third temperature T3).
  • the heat treatment temperature of the selective nitriding heat treatment may be in the range of 500 to 1500 degrees C (for example, 600 degrees to 1100 degrees C).
  • the heat treatment temperature when the heat treatment temperature is less than 500°C, the decomposition rate of the nitrogen-containing gas including nitrogen decreases and the nitrogen diffusion rate decreases, so it may be difficult to form the reinforcing compound 22 at a sufficient rate or amount.
  • the heat treatment temperature when the heat treatment temperature exceeds 1500 ° C, the alloy may undesirably melt beyond the melting point of the alloy, and the external diffusion of the metal increases, so it may be difficult to properly form the reinforcing compound 22 in the form of internal precipitates. .
  • partial aggregation of nitrides may occur on the surface, or initial nitridation may be non-uniform, and the form of the reinforcing compound 22 may also be non-uniform after nitriding. That is, in this embodiment, the initial nitridation is uniform by setting the heat treatment temperature of the selective nitridation heat treatment to 1500 degrees C (for example, 1100 degrees C) or less, and the aggregation of nitrides on the surface during selective nitriding heat treatment can be prevented. have.
  • the heat treatment temperature is 650 ° C. or higher, less than 900 ° C. (eg, 700 to 850 ° C, for example, 750 to 850 ° C)
  • temperature conditions that can efficiently form the reinforcing compound 22 becomes this That is, in the above-described temperature range, the surface diffusion of the metal is prevented and only nitrogen penetrates the first phase 20a so that the reinforcing compound 22 is selectively formed only in the first phase 20 , and the inside of the first phase 20 is formed. It can be evenly distributed to the depths.
  • the treatment temperature is less than 650 °C (for example, less than 700 °C)
  • the internal diffusion rate of nitrogen is lowered and it may be difficult to penetrate deep inside, and 900 °C or more (for example, more than 850 °C) )
  • the amount, thickness, density, etc. of the reinforcing compound 22 having an internal precipitate form formed inside the first phase 20 by forming a surface film by external diffusion of the metal may be reduced.
  • the present invention is not limited thereto, and the heat treatment temperature in the selective nitriding heat treatment may be variously changed in consideration of other process conditions.
  • the process time of the selective nitriding heat treatment may vary depending on the size and thickness of the reinforcing compound 22 , and the internal depth of the reinforcing compound 22 formed in the first phase 20 .
  • the process time of the selective nitriding heat treatment may be performed for about 1 minute to 10 hours, and for example, at 700 to 850 degrees Celsius, may be performed for about 1 hour to 3 hours. If the process time of the selective nitriding heat treatment is less than the above range, it may be difficult to sufficiently form the reinforcing compound 22, and if it is larger than the above range, the process may be complicated and the process cost may increase.
  • the present invention is not limited thereto, and the process time may be variously changed in consideration of other process conditions and the like.
  • the selective oxidation heat treatment may be performed using an oxygen-containing gas including oxygen at a heat treatment temperature higher than room temperature.
  • the heat treatment temperature of the selective oxidation heat treatment may be 500 °C to 1500 °C.
  • the heat treatment temperature may be less than 1100 °C (eg, 700 to 850 °C, for example, 750 to 850 °C).
  • the reinforcing compound 22 may be evenly formed to the deep inside in the form of internal precipitates, and may be formed in a sufficient amount, thickness, density, and the like.
  • the range of the heat treatment temperature is substantially limited for the same reason as the selective nitriding heat treatment, except that an oxide is formed instead of a nitride by using oxygen instead of nitrogen, and a detailed description thereof will be omitted.
  • the present invention is not limited thereto, and the heat treatment temperature in the selective oxidation heat treatment may be variously changed in consideration of other process conditions and the like.
  • the reactive gas used in the selective oxidation heat treatment may include an oxygen-containing gas.
  • the reactant gas may use a single oxygen gas (eg, O 2 ) as the main oxygen-containing gas to provide oxygen, and an oxygen-containing compound gas (eg, carbon monoxide gas (CO), carbon dioxide gas (eg, carbon monoxide gas (CO)) as an additional gas ( CO 2 ), or a mixture thereof ( a mixed gas of CO and CO 2 ) and/or a gas containing hydrogen (eg, moisture (H 2 O), a single hydrogen gas, H 2 , or of H 2 O and H 2 ) mixed gas) may be further used.
  • a single oxygen gas eg, O 2
  • an oxygen-containing compound gas eg, carbon monoxide gas (CO), carbon dioxide gas (eg, carbon monoxide gas (CO)
  • CO 2 additional gas
  • a gas containing hydrogen eg, moisture (H 2 O)
  • H 2 O a single hydrogen gas, H 2 , or of H 2 O and H
  • an oxygen-containing compound gas such as carbon monoxide or carbon dioxide or a hydrogen-containing gas such as moisture or a single hydrogen gas may be further used as an additional gas to broaden the oxygen partial pressure range causing selective oxidation.
  • the oxygen-containing compound gas may serve as an oxygen-containing gas that provides oxygen as an auxiliary.
  • a hydrogen-containing gas such as moisture or a single hydrogen gas may also serve to prevent problems such as damage to human life due to leakage of carbon monoxide and carbon dioxide.
  • Conditions under which selective oxidation occurs in selective oxidation heat treatment can be confirmed through an Ellingum diagram or experimentally.
  • the process time of the selective oxidation heat treatment may vary depending on the size and thickness of the reinforcing compound 22 , and the internal depth of the reinforcing compound 22 formed in the first phase 20 .
  • the process time of the selective oxidation heat treatment may be performed for about 1 minute to 10 hours, for example, at 750 to 850 degrees Celsius, it may be performed for about 1 hour to 3 hours. If the process time of the selective oxidation heat treatment is less than the above range, it may be difficult to sufficiently form the reinforcing compound 22, and if it is larger than the above range, the process may be complicated and the process cost may increase.
  • the present invention is not limited thereto, and the process time may be variously changed in consideration of other process conditions and the like.
  • the non-metal NM moves into the interior of the high-entropy alloy material 10a (in particular, the first phase 20a). It can penetrate and form the reinforcing compound 22 in the form of an internal precipitate.
  • a non-metal eg, nitrogen or oxygen
  • the metals M1 and M2 move to the surface and the non-metal NM moves to the surface of the high entropy alloy material 10a.
  • the surface film SF for example, a nitride film or an oxide film, or a layer forming part (reference numeral 222 in FIG. 1 ) is formed on the surface without penetrating into the inside of the first phase 20a).
  • the metal diffusion rate is low, so that the strengthening compound 22 may be non-uniformly formed.
  • the metal diffusion rate is high, so that a surface film may be formed.
  • the reinforcing compound 22 is uniformly formed in the first phase 20 of the high entropy alloy 10, if the process conditions cannot be precisely controlled or the surface film is partially formed, the surface film prevents the diffusion of non-metals. By suppressing it, the reinforcing compound 22 may be formed non-uniformly.
  • the reinforcing compound 22 may be formed at a high density near the surface and the reinforcing compound 22 may not be formed in the inner portion, or the reinforcing compound 22 may have a lower density than at the surface.
  • the heat treatment temperature, the type of the reaction gas (especially, the reaction gas containing hydrogen gas), the volume ratio, etc. are specifically limited, and the formation of the surface film as shown in FIG.
  • the non-metal (NM) By minimizing the effective diffusion of the non-metal (NM) to the inside, it is possible to uniformly form the reinforcing compound 22 in the form of an internal precipitate.
  • the non-metal composed of oxygen or nitrogen diffuses to the deep inside of the first phase 20 and the reinforcing compound 22 is uniformly formed to the deep inside of the first phase 20, the high entropy alloy 10 can greatly improve the wear resistance of
  • the present invention is not limited thereto.
  • the reinforcing compound 22 may have a layered form partially or entirely formed on the surface of the first phase 20 , or may include both the above-described plurality of precipitate forms and a layered form formed on the surface of the first phase 20 .
  • the strengthening compound 22 may be selectively formed in the first phase 20 by a simple process that specifically defines the process conditions of the selective strengthening step ST20.
  • the high entropy alloy 10 having the desired properties can be easily manufactured by performing the heat treatment method of the high entropy alloy 10 according to the present embodiment. have.
  • the reinforcing compound 22 may have an internal precipitate form or a layered form formed on the surface if necessary. Thereby, it is possible to manufacture the high entropy alloy 10 having excellent ductility, strength, hardness and wear resistance through a simple process.
  • the high entropy alloy according to the present embodiment may be used in the manufacture of various products.
  • the high-entropy alloy according to the present embodiment may be used for manufacturing an Oldam Ring that prevents the scroll from rotating in a scroll compressor and enables only left and right revolutions.
  • Oldham ring must have excellent hardness and wear resistance for long-term reliability.
  • Oldham ring having excellent hardness and wear resistance can be manufactured.
  • the present invention is not limited thereto.
  • the high-entropy alloy 10 having the first phase 20 composed of the iron-rich phase and the second phase 30 composed of the copper-rich phase is taken as an example, and while reducing material costs, the iron- It was designed to have both excellent strength by the rich phase and excellent ductility by the copper-rich phase.
  • the present invention is not limited thereto. Therefore, it can be applied to various high entropy alloys 10 having the first phase 20 and the second phase 30 having different compositions.
  • a high-entropy alloy material of Al 15 (FeCuMn) 85 having a first phase and a second phase containing iron, copper, aluminum and manganese in the content (at%) shown in Table 3 was prepared and heated at a heat treatment temperature of 700 ° C.
  • a high-entropy alloy was prepared by providing a reaction gas and performing selective nitriding heat treatment. At this time, a single nitrogen gas, ammonia gas, and hydrogen gas were used as the reaction gas in a volume ratio of 0.855: 0.095: 0.05.
  • a high entropy alloy was prepared by performing selective nitriding heat treatment on the high entropy alloy material in the same manner as in Example 1, except that the heat treatment temperature was 800°C.
  • a high entropy alloy was prepared by performing selective nitriding heat treatment on the high entropy alloy material in the same manner as in Example 1, except that the heat treatment temperature was 900°C.
  • FIG. 6 Field emission scanning electron microscope (FE-SEM) pictures of the high entropy alloy materials used in Examples 1 to 3 are shown in FIG. 6 .
  • the high-entropy alloy material according to Example 1 had a relatively darkly displayed first phase (a portion indicated by number 1 in the upper row of FIG. 6 , the upper left row of FIG. 6 ) and a relatively brightly displayed second phase (upper row of FIG. 6 ). It can be seen that the part indicated by the number 2 in the left drawing) is provided.
  • FIG. 7 An optical micrograph of a cross section of the high entropy alloy according to Example 1 is attached to FIG. 7 .
  • Figure 7 (a) is a photograph of performing the selective nitriding heat treatment for 1 hour
  • Figure 7 (b) is a photograph of performing the selective nitriding heat treatment for 2 hours.
  • a portion that is discolored darker than the relatively darkly displayed first phase in the optical micrograph is a portion in which a nitride or a nitride film constituting the reinforcing compound is formed.
  • FIG. 8 An optical micrograph of a cross section of the high entropy alloy according to Example 2 is attached to FIG. 8 .
  • Fig. 8 (a) is a photograph of performing selective nitriding heat treatment for 1 hour
  • Fig. 8 (b) is a photograph of performing selective nitriding heat treatment for 2 hours.
  • nitride or a nitride film is formed near the surface during selective nitridation heat treatment at 800°C for 1 hour.
  • nitride was formed to a depth of up to 60 ⁇ m during selective nitriding heat treatment at 800° C. for 2 hours.
  • FIG. 9 An optical micrograph of a cross section of the high entropy alloy according to Example 3 is attached to FIG. 9 .
  • Fig. 9 (a) is a photograph of performing selective nitriding heat treatment for 1 hour
  • Fig. 9 (b) is a photograph of performing selective nitriding heat treatment for 2 hours.
  • nitride is formed deep inside and nitridation is made relatively uniformly.
  • the heat treatment temperature is 900°C
  • aggregation of nitrides was found compared to 700°C and 800°C.
  • the nitride is uniformly formed even deeper inside the case where the heat treatment temperature is 800°C than when the heat treatment temperature is 700°C. That is, if the selective nitridation heat treatment is performed at a heat treatment temperature of 750 to 850° C. for a process time of 1 hour to 3 hours, nitride may be uniformly formed even deeper inside.
  • FIGS. 10 to 12 FE-SEM/EDS photos of the high entropy alloys according to Examples 1 to 3 in which selective nitriding heat treatment was performed for 2 hours are shown in FIGS. 10 to 12, respectively.
  • FIG. 10 it can be seen that in the high entropy alloy according to Example 1, manganese and aluminum did not diffuse to the surface, but only nitrogen penetrated into the first phase and nitridation proceeded.
  • FIG. 11 it can be seen that in the high entropy alloy according to Example 2, a phenomenon in which the manganese concentration increases on the surface of the second phase occurs.
  • FIG. 12 it can be seen that in the high entropy alloy according to Example 3, a phenomenon in which the concentrations of manganese and aluminum were increased on the surfaces of the first and second phases occurred.
  • the diffusion temperature of nitrogen and the diffusion rate of the metal are similar in the first phase, so that the manganese and Aluminum can form nitrides at the same time.
  • the high entropy alloy material comparative example
  • the nitrogen content was measured by glow discharge analysis.
  • the resolution of the measuring equipment was ⁇ 0.025 nm and the amount of detectable components was 0.1 ppm.
  • Example 13 it can be seen that the surface nitrogen content is significantly higher in the high entropy alloy according to Example 2, where the heat treatment temperature is 800° C., compared to the high entropy alloy according to Example 3, where the heat treatment temperature is 900° C.
  • the surface nitrogen content was increased, but it was found to be small compared to Examples 2 and 3.
  • the heat treatment temperature is 900 ° C., it is difficult for ammonia to stably exist due to vapor phase decomposition, so it can be predicted that the nitrogen content appears higher in the high entropy content according to Example 2 where the heat treatment temperature is 800 ° C.
  • Example 15 and 16 in the high entropy alloys according to Examples 2 and 3, the content of each element was changed according to depth. In particular, it can be seen that the manganese content greatly increases on the surface and there is a section where the content decreases as it enters the interior. It can be seen that manganese migrated to the surface by diffusion and the nitrogen content also increased at the surface, suggesting that the diffused manganese reacts with nitrogen on the surface to form nitride. In Example 3, the diffusion rate of the metal element was very high, and the content change according to diffusion occurred the most, and it can be seen that the degree of nitridation by vapor phase decomposition of ammonia was lower than in Example 2.
  • the inside of the first phase and the inside of the second phase do not show a significant difference in hardness before and after heat treatment.
  • the hardness is greatly increased to have approximately 2 to 4 times the hardness after the selective nitriding heat treatment on the surface of the first phase.
  • the degree of hardness increase on the surface of the first phase in Example 3 in which the heat treatment temperature was 900 degrees Celsius was not greater than in Examples 1 and 2. This is expected to be small in the degree of hardness increase in Examples 1 and 2 because, in Example 3, the internal manganese and aluminum diffuse more during the selective nitriding heat treatment to form a non-uniform nitride by reacting with nitrogen on the surface. And it is predicted that the nitrogen concentration at the surface is lower than in Example 2, so that nitridation occurs less than in Example 2.
  • Example 2 it can be seen that in Examples 1 to 3, the nitriding treatment was selectively performed on the first phase. In particular, in Example 2, it can be seen that the nitriding treatment was selectively performed to have excellent hardness.
  • the mass change rate of the base material (high entropy alloy) and the counterpart material according to Examples 1 to 3, that is, the loss amount is smaller than the mass change rate of the base material (high entropy alloy material) and the counterpart material according to Comparative Example 1 can And referring to FIG. 18 , it can be seen that the width of the wear track of the high entropy alloy according to Examples 1 to 3 is smaller than the width of the wear track of the high entropy alloy material according to Comparative Example 1. This is expected to be due to the formation of nitrides, ie, hardening compounds, due to the selective nitridation heat treatment.
  • the width of the wear track is the smallest, and the mass change rate is reduced by 90% or more compared to the high entropy alloy material according to the comparative example, so that the wear resistance is 10 times or more It can be seen that increased
  • FIG. 19 (b) and (c) are optical micrographs showing an enlarged part of (a) of FIG. 19 .
  • the cross section of the high entropy alloy according to Example 2 may have a difference in shape density and the like near the surface and in the inner portion. That is, as shown in (b) and (c) of Figure 19, the nitride is formed in the form of fine precipitates near the surface, and in the inner part, the nitride has a larger size, thickness, length, area, etc. than near the surface. . As such, when a finer nitride is distributed near the surface, hardness and wear resistance in the vicinity of the surface can be improved.

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Abstract

Un alliage à entropie élevée, selon le présent mode de réalisation de l'invention, comprend une première phase et une deuxième phase comprenant respectivement du fer et du cuivre, et du fer et un premier métal autre que le cuivre, et ayant des compositions mutuellement différentes. Un composé de renforcement formé par la liaison chimique du premier métal et d'un non-métal peut être sélectivement inclus dans la première phase.
PCT/KR2020/008188 2020-06-23 2020-06-23 Alliage à entropie élevée et procédé de traitement thermique de celui-ci WO2021261609A1 (fr)

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN114956804A (zh) * 2022-06-23 2022-08-30 中国民航大学 一种钙钛矿型高熵陶瓷材料及其制备方法
CN115216677A (zh) * 2022-07-07 2022-10-21 北京理工大学 一种第二相均匀分布强化的高熵合金材料及其制备方法

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