CN-116358962-B - Preparation method of CoFeNi medium-entropy alloy tensile sample under deep supercooling condition

CN116358962BCN 116358962 BCN116358962 BCN 116358962BCN-116358962-B

Abstract

The invention provides a preparation method of a CoFeNi medium entropy alloy tensile sample under a deep supercooling condition, wherein the alloy deep supercooling process of the preparation method is carried out by a high-frequency induction heating device and a mode of combining a melt dipping method and a circulating overheat method, the smelting process firstly sequentially places single substances of all alloy raw materials into a quartz crucible from bottom to top according to a sequence from high melting point to low melting point, and adds glass purifying agents into the lowest layer and the uppermost layer of the alloy raw materials, and during smelting, the glass purifying agents are sequentially melted and coated on the alloy surface, the melting of Ni metal raw materials and the melting of other metal raw materials by controlling the vertical movement of the quartz crucible in the central axis direction of a high-frequency induction coil and the heating temperature of the high-frequency induction coil, the alloy liquid is sufficiently mixed, cooled and solidified, and repeatedly heated, cooled and solidified until 205K supercooling degree is obtained, so that a CoFeNi medium entropy alloy ingot meeting the tensile test size is prepared. The invention has the advantages of easy control of the solidification process, mature process and small component loss.

Inventors

WANG WEILI
LI WENHUI
LI NAN
DING SHUJIAN

Assignees

西北工业大学

Dates

Publication Date: 20260505
Application Date: 20230403

Claims (6)

1. A preparation method of an entropy alloy tensile sample in CoFeNi under a deep supercooling condition is characterized in that an alloy deep supercooling process of the preparation method is carried out by a high-frequency induction heating device and adopting a mode of combining a melt dipping method and a circulating overheat method, single substances of all alloy raw materials are sequentially put into a quartz crucible from bottom to top according to a sequence from high melting point to low melting point, glass purifying agents are added into the lowest layer and the uppermost layer of the alloy raw materials, during smelting, the glass purifying agents are sequentially melted and coated on the alloy surface, the melting of Ni metal raw materials and the melting of other metal raw materials through controlling the vertical movement of the quartz crucible in the central axis direction of a high-frequency induction coil and the heating temperature of the high-frequency induction coil, cooling solidification is carried out after the alloy liquid is fully mixed, and heating and cooling solidification are repeated until 205K supercooling degree is obtained, so that an entropy alloy ingot in CoFeNi meeting a tensile test size is prepared, and the preparation method specifically comprises the following steps: Step 1, burdening, namely weighing each metal simple substance according to the mole percentage Co: fe: ni=1:1:1 of each element of the entropy alloy in CoFeNi by taking each element simple substance as a raw material, and configuring the raw material; Step 2, discharging, namely selecting a quartz crucible with a cylindrical upper end opening, and sequentially placing the prepared raw materials into the quartz crucible, wherein the raw materials are placed into the quartz crucible from bottom to top according to the sequence of glass purifying agents, fe, co, ni and glass purifying agents according to the melting point; Step 3, adjusting the position of the crucible, namely controlling the quartz crucible to vertically move up and down along the central axis direction of the high-frequency induction coil by adopting an electric push rod device, so that the contact surface of the glass purifying agent at the upper middle part of the quartz crucible and the Ni simple substance is positioned at an effective heating position in the vertical direction of the high-frequency induction coil; Step 4, vacuumizing, namely after the vacuum cavity door is closed, opening a cold water machine, vacuumizing the vacuum arc cavity to 10 -3 Pa or more, closing an air extraction valve, opening an air inlet valve, reversely filling high-purity argon into the cavity to 0.5 standard atmospheric pressure, and closing the air inlet valve; Step 5, heating the alloy to 1073-1173 ℃ through a high-frequency induction coil, observing the softening condition of the glass purifying agent through a high-speed CCD, and preserving heat for 1min to enable the glass purifying agent to be fused and coated on the surface of the alloy; Step 6, heating to 1400-1500 ℃, and then preserving heat for 1min to ensure that the Ni metal simple substance is completely melted; Step 7, heating to 1650-1850 ℃, controlling an electric push rod device to enable the quartz crucible to move upwards, melting Co and Fe metal simple substances through high-frequency induction heating and heat conduction between metals, stopping moving the quartz crucible after complete melting, preserving heat for 2min, fully mixing alloy liquid by virtue of electromagnetic stirring, and closing high frequency for cooling and solidification; step 8, observing a temperature curve acquired by an infrared probe, and opening high frequency to continue heating when the temperature is reduced to 850-900 ℃; step 9, rapidly heating to 1650-1850 ℃ and preserving heat for 1min, and closing high frequency to cool and solidify; And 10, repeating the step 8 and the step 9 until the supercooling degree of 205K is obtained, cooling for 3 hours, and taking out a cylindrical CoFeNi alloy sample with uniform components.
2. The method for preparing a tensile sample of an entropy alloy in CoFeNi under the condition of deep supercooling as claimed in claim 1, wherein the quartz crucible used has the specification of 16mm in inner diameter, 20mm in outer diameter and 100mm in height, and the addition height of the alloy raw material is 4/5 of the height of the quartz crucible.
3. The method for preparing a tensile sample of an entropy alloy in CoFeNi under the condition of deep supercooling according to claim 1, wherein the total amount of the alloy raw material is 60g, and the total amount of the glass purifying agent is 9-10g.
4. The method for preparing the tensile sample of the entropy alloy in CoFeNi under the condition of deep supercooling as claimed in claim 1, wherein one end of an electric push rod of the electric push rod device is connected with a crucible base made of boron nitride, a quartz crucible is placed on the crucible base, and the electric push rod device is electrically connected with an external control switch for controlling the quartz crucible to move up and down along the central axis direction of the high-frequency induction coil.
5. The method for preparing a tensile sample of an entropy alloy in CoFeNi under the condition of deep supercooling as claimed in claim 1, wherein the length of the obtained cylindrical CoFeNi alloy sample is up to 30mm or more.
6. The method for preparing a tensile sample of an entropy alloy in CoFeNi under the condition of deep supercooling as claimed in any one of claims 1 to 5, wherein the glass purifying agent is glass having a main component Na 2 O·CaO·6SiO 2 .

Description

Preparation method of CoFeNi medium-entropy alloy tensile sample under deep supercooling condition Technical Field The application belongs to the technical field of alloy preparation, and particularly relates to a preparation method of a CoFeNi medium entropy alloy tensile sample under a deep supercooling condition. Background The medium entropy alloy is an alloy composed of three elements in equimolar or nearly equimolar ratio, and the composition characteristics of the medium entropy alloy lead the medium entropy alloy to have high strength, high hardness, good wear resistance, high resistivity, excellent corrosion resistance, excellent magnetic property, good hydrogen storage property and the like, so that the medium entropy alloy has great interest in the alloy systems. Of these, coFeNi is a single-phase disordered solid solution alloy with FCC crystal structure, exhibiting lower yield strength. At present, most of researches adopt an arc melting device to prepare CoFeNi alloy ingots, coarse grains are easy to form, the mechanical properties of the alloy and the like are adversely affected, and the application of the alloy as a structural material is limited. Compared with the equilibrium solidification process such as arc melting, the rapid solidification process can obviously reduce the generation of structural defects and refine grains. The dendrite growth and solidification mechanism of alloys under deep supercooling conditions has been receiving extensive attention from researchers for many years, and the thermodynamic and kinetic theory of metal melts under deep supercooling rapid solidification conditions has been matured. According to the research and retrieval of the literature, the patent name of the solidification method for obtaining the stable supercooling degree of 210-430K by the multi-element alloy is found in the Chinese patent office publication No. CN 103643063A, the deep supercooling solidification of the multi-element alloy is realized by adopting a method combining molten glass purification, temperature control and glass purifying agent cleaning, and a button alloy ingot with the mass of 30/120g is obtained, and the size still cannot meet the tensile mechanical test size. The patent name of China patent office publication No. CN1552544A, the method for preparing the directional alloy material by in-situ deep supercooling, the method for preparing the directional alloy by combining molten glass purification and cyclic overheating is proposed, and the alloy in the first quartz tube is leaked into the second quartz tube after reaching the softening point in the preparation process, so that the method has a certain rejection rate. Disclosure of Invention The invention aims to overcome the defects in the prior art, and provides a preparation method of an entropy alloy tensile sample in CoFeNi under a deep supercooling condition, so that the difficult problem of insufficient height of the tensile sample is solved. The invention is realized by the method, the alloy deep supercooling process of the preparation method is carried out by a high-frequency induction heating device and adopting a mode of combining a melt dipping and floating method and a circulating overheat method, the smelting process firstly sequentially puts the elementary substances of all alloy raw materials into a quartz crucible from bottom to top according to the sequence of melting points, and adds glass purifying agents into the lowest layer and the uppermost layer of the alloy raw materials, and the glass purifying agents are sequentially melted and coated on the alloy surface, the melting of Ni metal raw materials and the melting of other metal raw materials by controlling the vertical movement of the quartz crucible in the central axis direction of a high-frequency induction coil and the heating temperature of the high-frequency induction coil during smelting, the alloy liquid is cooled and solidified after being fully mixed, and the heating and the cooling solidification are repeated until 205K supercooling degree is obtained, so that the alloy ingot in CoFeNi meeting the stretching test size is prepared. The invention is also characterized in that the preparation method comprises the following steps: step 1, burdening, namely weighing each metal simple substance according to the mole percentage Co: fe: ni=1:1:1 of each element of the entropy alloy in CoFeNi by taking each element simple substance as a raw material, and configuring the raw material; Step 2, discharging, namely selecting a quartz crucible with a cylindrical upper end opening, sequentially placing the prepared raw materials into the quartz crucible, and laying the raw materials into the quartz crucible from bottom to top according to the sequence of glass purifying agents, fe, co, ni and glass purifying agents according to the melting point when the raw materials are placed; Step 3, adjusting the position of the crucible, namely controlling the quar