Solute refined alloy structure designed based on mixing enthalpy and solidification interval and preparation method

Abstract

The invention provides a solute refined alloy structure designed based on mixing enthalpy and solidification interval and a preparation method, the alloy is a ternary alloy Ti100-2x-Ax-Dx, x is 0.1-0.5, A and D are a metal refined element and a non-metal refined element; the mixing enthalpy of the element A and the element D is-45 to-65 kJ / mol, the mixing enthalpy of the element Ti and the element A is-120 to 15 kJ / mol, and the mixing enthalpy of the element Ti and the element D is-50 to 15 kJ / mol; the solidification interval of the alloy structure is greater than 50 DEG C; the solute distribution coefficients of the A element and the D element are both smaller than 1. According to the method, grain refinement solute component design is carried out according to the dual principles of mixing enthalpy and solidification interval, the solute element pairs suitable for refining the Ti alloy with the high affinity characteristic can be more effectively screened out, and proper interaction exists between the solute element pairs.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy refined grain structure regulation, and particularly to a method for refining alloy structure by solute based on mixing enthalpy and solidification range design and a preparation method thereof. Background Art

[0002] Structural materials such as titanium alloys, high-temperature alloys, and aluminum-magnesium alloys have become important basic materials in the fields of aerospace, ocean engineering, and biomedicine due to their excellent comprehensive properties, and are widely used in major national projects and strategic emerging industries.

[0003] However, the alloy structures obtained by casting and additive manufacturing usually exhibit the characteristics of coarse columnar grains, with significant anisotropic mechanical properties, which limits their application in structural materials. Research shows that refining grains is an effective way to improve their anisotropy. Although traditional grain refinement methods have been widely applied in the casting process, they face challenges in the additive manufacturing process. For example, inoculation / modification methods are difficult to implement, and external field methods such as ultrasonic and electromagnetic stirring are limited by the rapid solidification characteristics, and their refinement effects are far less than those in casting, especially difficult to achieve in an industrial environment. Therefore, there is an urgent need to propose a grain refinement method that is universal for casting and additive manufacturing. Summary of the Invention

[0004] In view of this, the present invention proposes a method for refining alloy structure by solute based on mixing enthalpy and solidification range design and a preparation method thereof. The purpose of the present invention is to design the type and content of solute addition to refine the alloy solidification structure based on the microalloying method according to the dual principles of the mixing enthalpy between solute elements and the solidification range of the solute-added alloy. This principle is applicable to various alloys such as titanium alloys, superalloys, and stainless steels. By utilizing the segregation of two elements at the solid-liquid interface front and their mutual attraction during the solidification process to inhibit grain growth, the purpose of promoting columnar grain-equiaxed grain transformation and grain refinement through microalloying is achieved. This method effectively solves the problem that the solute effect is insufficient during the grain refinement process of current alloy materials and it is difficult to effectively induce the formation of finer equiaxed grains.

[0005] The technical solution of the present invention is realized as follows: In the first aspect, the present invention provides an alloy structure refined by solute based on mixing enthalpy and solidification range design, and the alloy is a ternary alloy Ti 100-2x -A x -D x , where x is 0.1 to 0.5, and A and D are metal refining elements and non-metal refining elements;

[0006] The mixing enthalpy of element A and element D is -45 to -65 kJ / mol, the mixing enthalpy of element Ti and element A is -120 to 15 kJ / mol, and the mixing enthalpy of element Ti and element D is -50 to 15 kJ / mol; the solidification range of the alloy structure is greater than 50 °C; the solute distribution coefficients of element A and element D are both less than 1.

[0007] Based on the above technical solutions, preferably, element A is boron, element D is terbium, and the alloy is Ti 100-2x -B x -Tb x 。

[0008] Based on the above technical solutions, preferably, the alloy is an equiaxed crystal ingot with isotropy.

[0009] In a second aspect, the present invention also provides a preparation method for designing a solute-refined alloy structure based on the mixing enthalpy and solidification range, including the following steps:

[0010] S1, Weigh Ti 100-2x -A x -D x raw materials, Ti raw material, A raw material, and D raw material according to the stoichiometric ratio, and then put these raw materials into a melting crucible;

[0011] S2, Arc melt the alloy raw materials under an argon atmosphere, stir during the melting process to make the distribution of each element uniform, and let it stand after melting to cool and solidify the melt to obtain a button ingot;

[0012] S3, Drop-cast the button ingot under its own gravity to obtain a Ti alloy.

[0013] Based on the above technical solutions, preferably, when element A and element D are non-metallic elements, they are added in powder form, and when placing the powder raw materials, they are surrounded by metal grains corresponding to other metal elements.

[0014] Based on the above technical solutions, preferably, the Ti raw material is Ti metal grains, the A raw material is boride powder or boron powder, and the D raw material is terbium powder.

[0015] Based on the above technical solutions, preferably, the stirring is achieved by applying an eddy current magnetic field to the molten metal during the melting process, and the current used to generate the eddy current magnetic field does not exceed 15 A.

[0016] Based on the above technical solutions, preferably, the melting current applied for the arc melting does not exceed 450 A.

[0017] Based on the above technical solutions, preferably, the arc melting and the subsequent cooling and solidification are carried out in multiple cycles, with at least 5 cycles.

[0018] Based on the above technical solutions, preferably, the melting time for each melting is not less than 3 min.

[0019] In a third aspect, the present invention also provides a design method for refining alloy microstructure by solutes, which is achieved by controlling the following conditions:

[0020] The alloy is a ternary alloy Ti 100-2x -A x -D x , where x is 0.1 - 0.5, and A and D are metal refining elements and non-metal refining elements;

[0021] The mixing enthalpy of element A and element D is -45 to -65 kJ / mol, the mixing enthalpy of Ti element and A element is -120 to 15 kJ / mol, and the mixing enthalpy of Ti element and D element is -50 to 15 kJ / mol; the solidification range of the alloy microstructure is greater than 50 °C; the solute distribution coefficients of both element A and element D are less than 1.

[0022] The design method for refining alloy microstructure by solutes and the preparation method based on mixing enthalpy and solidification range according to the present invention have the following beneficial effects compared with the prior art:

[0023] (1) The present invention designs the solute components for grain refinement by using the dual principles of mixing enthalpy and solidification range. This method can more effectively screen out solute element pairs suitable for refining Ti alloys with strong affinity characteristics, and there is a suitable interaction between the solute element pairs.

[0024] (2) By using the present invention, by co-adding two grain refinement elements with solute interaction at the solidification front (i.e., element A and element D, whose mixing enthalpy is in the range of -45 to -65 kJ / mol, and these two elements are two refinement elements with suitable binding force), the goal of promoting the columnar - equiaxed grain transformation and refining grains can be achieved, so that the cast or additive manufactured Ti alloy obtains an equiaxed grain structure, and the tissue distribution is uniform, the grains are fine and isotropic.

[0025] (3) The preparation method of the present invention has the characteristic of less element addition amount. Using microalloying to achieve the columnar - equiaxed grain transformation and grain refinement helps to reduce the excessive precipitation of harmful phases. Description of the Drawings

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0027] Figure 1 For the Ti in Example 1 99.8 -B 0.1 -Tb 0.1 Solidification microstructure diagram of the alloy (Ti-0.1B-0.1Tb);

[0028] Figure 2 For the Ti in Example 2 99.7 -B 0.15 -Tb 0.15 Solidification microstructure diagram of the alloy (Ti-0.15B-0.15Tb);

[0029] Figure 3 For the Ti in Example 3 99.4 -B 0.2 -Tb 0.2 Solidification microstructure diagram of the alloy (Ti-0.2B-0.2Tb);

[0030] Figure 4 Solidification microstructure diagram of Ti in Comparative Example 1. Specific embodiments

[0031] The following will describe clearly and completely the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0032] The present invention provides a method for designing a solute-refined alloy microstructure based on the mixing enthalpy and solidification range. The alloy is a ternary alloy Ti 100-2x -A x -D x , where x is 0.1 to 0.5.

[0033] Among them, A and D are metal refining elements and non-metal refining elements. The mixing enthalpy of element A and element D is -45 to -65 kJ / mol, the mixing enthalpy of Ti element and A element is -120 to -15 kJ / mol, the mixing enthalpy of Ti element and D element is -50 to -15 kJ / mol. The solidification range of the alloy microstructure is greater than 50 °C; the solute distribution coefficients of both A element and D element are less than 1.

[0034] Preferably, in one embodiment, the A element is boron, the D element is terbium, and the alloy is Ti 100-2x -B x -Tb x , where x is from 0.1 to 0.5.

[0035] In another embodiment, the A element is boron, the D element is lutetium, and the alloy is Ti 100-2x -B x -Lu x , where x is from 0.1 to 0.5.

[0036] In other embodiments, the method for designing a solute-refined alloy microstructure based on mixing enthalpy and solidification range of the present invention is also suitable for other materials such as high-temperature, high-entropy alloys, aluminum-magnesium alloys, etc. Just replace Ti with materials such as Ni, Fe, Al, Mg, etc., and the A element and D element are screened according to appropriate mixing enthalpy and solidification range, and a uniform tissue distribution, fine grains, and isotropic equiaxed crystal structure can also be achieved.

[0037] The alloy is an equiaxed crystal ingot and has isotropy.

[0038] The alloy is Ti 100-2x -B x -Tb x The preparation method includes the following steps:

[0039] S1, Weigh the Ti raw material, A raw material, and D raw material according to the stoichiometric ratio of Ti 100-2x -A x -D x , and then put these raw materials into a melting crucible.

[0040] When the A element and D element are non-metallic elements, they are added in the form of powder, and when placing the powder raw materials, they are surrounded by metal grains corresponding to other metal elements.

[0041] The Ti raw material is Ti metal grains, the A raw material is boride powder or boron powder, and the D raw material is terbium powder.

[0042] S2, Arc-melt the alloy raw materials under an argon atmosphere, stir during the melting process to make the distribution of each element uniform, and let the melt cool and solidify after melting is completed to obtain a button ingot.

[0043] The stirring is achieved by applying an eddy current magnetic field to the molten metal during the melting process, and the current used to generate the eddy current magnetic field does not exceed 15 A.

[0044] The melting current applied for the arc melting does not exceed 450 A.

[0045] The arc melting and the subsequent cooling and solidification are carried out in multiple cycles, with at least 5 cycles; the melting time for each melting is not less than 3 minutes.

[0046] S3. Drop-casting the button ingot under its own gravity to obtain the Ti alloy.

[0047] The following further details the Ti alloy and its preparation method based on the design of solute-refined grains using mixing enthalpy and solidification range, in combination with examples and comparative examples.

[0048] Example 1

[0049] This example provides a Ti alloy and its preparation method based on the design of solute-refined grains using mixing enthalpy and solidification range. The alloy is Ti 99.8 -B 0.1 -Tb 0.1 , and the specific preparation method includes the following steps:

[0050] Step 1: Design and select the solute pair elements and their addition contents for refining the grains of the Ti alloy according to the dual principles of mixing enthalpy and solidification range. Element A is boron, with an addition content of 0.1 at.%, and the addition form is TiB 2 powder; Element D is terbium, with an addition content of 0.1 at.%, and the addition form is Tb powder.

[0051] Among them, the mixing enthalpy of boron and terbium is -51 kJ / mol, the mixing enthalpy of titanium and boron is -58 kJ / mol, and the mixing enthalpy of titanium and terbium is 14 kJ / mol. The solidification range for adding 0.1 at.% boron to titanium is 63 °C, and the solidification range for adding 0.1 at.% terbium to titanium is 52 °C.

[0052] Step 2: Weigh the corresponding masses of Ti raw materials, TiB 99.8 -B 0.1 -Tb 0.1 (at.%, atomic percentage) components, and then place them in a melting crucible. Among them, the powder raw materials are placed in the middle of the Ti metal particles to prevent them from being blown away by the arc during melting. 2 The alloy raw materials are continuously subjected to multiple arc meltings under an argon atmosphere, and stirring is carried out during the melting process to achieve uniform distribution of each element. After the melt solidifies, a button ingot is obtained.

[0053] Step 3: Evacuate the arc furnace to less than 2×10

[0054] Pa, and then backfill argon to about 5×10 -2 Pa, and then backfill argon to about 5×10 4Pa, repeat the operation 2 times. Then, under an argon atmosphere, the alloy raw materials are continuously subjected to arc melting 5 times, and electromagnetic stirring is carried out during the melting process to obtain a melt with uniform composition. After the metal melt is completely solidified, an alloy button ingot is obtained.

[0055] Among them, the melting current of the arc melting is 350 A, and the arc melting time is 3 minutes each time.

[0056] During arc melting, an eddy current magnetic field is applied for electromagnetic stirring, and the current intensity of the eddy current magnetic field is 10 A.

[0057] Step 4: Under the argon atmosphere in the arc furnace, after moving the alloy button ingot to the pouring station, arc is struck and the current is slowly increased to melt the button ingot. When the bottom alloy is completely melted and quickly drops into the mold directly below the station, a Ti alloy ingot is obtained.

[0058] The solidification microstructure diagram of the Ti-0.1B-0.1Tb alloy prepared in Example 1 is as Figure 1 shown. A stereomicroscope is used for metallographic structure observation. Small cubes with dimensions of 15 mm×10 mm×5 mm are cut from the sample by wire cutting, and are polished brightly successively with SiC sandpapers of 80#, 120#, 240#, 500#, 800#, 1000#, 1200# and 2000#, then mechanically polished, and the surface of the sample is etched with an etching solution for microstructure observation. After testing, the average size of the equiaxed crystal grains of the alloy obtained in Example 1 is 820 μm.

[0059] Example 2

[0060] This example provides a Ti alloy for refining grains of solute based on mixing enthalpy and solidification range and a preparation method thereof. The alloy is Ti 99.7 -B 0.15 -Tb 0.15 , and the specific preparation method includes the following steps:

[0061] Step 1: Design and select the solute pair elements and their addition contents for refining the grains of the Ti alloy according to the dual principles of mixing enthalpy and solidification range. Element A is boron, the addition content is 0.15 at.%, and the addition form is TiB 2 powder; Element D is terbium, the addition content is 0.15 at.%, and the addition form is Tb powder.

[0062] Among them, the mixing enthalpy of boron element and terbium element is -51 kJ / mol, the mixing enthalpy of titanium element and boron element is -58 kJ / mol, and the mixing enthalpy of titanium element and terbium element is 14 kJ / mol. The solidification range of adding 0.15 at.% boron element to titanium is 89 °C, and the solidification range of adding 0.15 at.% terbium element to titanium is 56 °C.

[0063] Step 2: According to the Ti 99.7 -B 0.15 -Tb 0.15 (at.%, atomic percentage), weigh the corresponding masses of Ti raw materials, TiB 2 raw materials, and Tb raw materials, and then put them into the melting crucible. Among them, the powder raw materials are placed in the middle of the Ti metal particles to prevent them from being blown away by the electric arc during melting.

[0064] Under an argon atmosphere, the alloy raw materials are continuously subjected to multiple arc melting processes, and stirring is carried out during the melting process to achieve uniform distribution of each element. After the melt solidifies, a button ingot is obtained.

[0065] Step 3: Vacuum the arc furnace to less than 2×10 -2 Pa, and then backfill argon to about 5×10 4 Pa, and repeat the operation 2 times. Then, under an argon atmosphere, the alloy raw materials are continuously subjected to 5 arc melting processes, and electromagnetic stirring is carried out during the melting process to obtain a melt with uniform composition. After the metal melt is completely solidified, an alloy button ingot is obtained.

[0066] Among them, the melting current of the arc melting is 350 A, and the arc melting time is 3 minutes each time.

[0067] During arc melting, an eddy current magnetic field is applied for electromagnetic stirring, and the current intensity of the eddy current magnetic field is 10 A.

[0068] Step 4: Under the argon atmosphere in the arc furnace, after moving the alloy button ingot to the pouring station, arc ignition is carried out and the current is slowly increased to melt the button ingot. When the bottom alloy is completely melted and quickly drips into the mold directly below the station, a Ti alloy ingot is prepared.

[0069] The solidification microstructure diagram of the Ti-0.15B-0.15Tb alloy prepared in Example 2 is as Figure 2 shown. A stereomicroscope is used for metallographic microstructure observation. A small cube with dimensions of 15 mm×10 mm×5 mm is cut from the sample by wire cutting, and is polished brightly successively with 80#, 120#, 240#, 500#, 800#, 1000#, 1200#, and 2000# SiC sandpapers, and then mechanically polished. The surface of the sample is corroded with the etching solution for microstructure observation.

[0070] After testing, the average size of the equiaxed crystal grains of the alloy obtained in Example 2 is 550 μm.

[0071] Example 3

[0072] This example provides a Ti alloy and a preparation method for refining grains of solutes based on mixing enthalpy and solidification range. The alloy is Ti 99.6 -B0.2 -Tb 0.2 , the specific preparation method includes the following steps:

[0073] Step 1: Design and select the solute pair elements and their addition contents for refining the Ti alloy grains according to the double principles of mixing enthalpy and solidification range. Element A is boron, the addition content is 0.2 at.%, and the addition form is TiB 2 powder; Element D is terbium, the addition content is 0.2 at.%, and the addition form is Tb powder.

[0074] Among them, the mixing enthalpy of boron element and terbium element is -51 kJ / mol, the mixing enthalpy of titanium element and boron element is -58 kJ / mol, and the mixing enthalpy of titanium element and terbium element is 14 kJ / mol. The solidification range of adding 0.2 at.% boron element to titanium is 113 °C, and the solidification range of adding 0.2 at.% terbium element to titanium is 124 °C.

[0075] Step 2: Weigh the corresponding masses of Ti 99.6 -B 0.2 -Tb 0.2 (at.%, atomic percentage) components of Ti raw materials, TiB 2 raw materials, and Tb raw materials, and then put them into the melting crucible. Among them, the powder raw materials are placed in the middle of the Ti metal particles to prevent being blown away by the arc during melting.

[0076] Under the argon atmosphere, the alloy raw materials are continuously subjected to multiple arc melting, and stirring is carried out during the melting process to achieve uniform distribution of each element. After the melt solidifies, a button ingot is obtained.

[0077] Step 3: Vacuum the arc furnace to less than 2×10 -2 Pa, and then backfill argon to about 5×10 4 Pa, and repeat the operation 2 times. Then, under the argon atmosphere, the alloy raw materials are continuously subjected to 5 times of arc melting, and electromagnetic stirring is carried out during the melting process to obtain a melt with uniform composition. After the metal melt is completely solidified, an alloy button ingot is obtained.

[0078] Among them, the melting current of the arc melting is 350 A, and the arc melting time is 3 minutes each time.

[0079] During arc melting, an eddy current magnetic field is applied for electromagnetic stirring, and the current intensity of the eddy current magnetic field is 10 A.

[0080] Step 4: Under the argon atmosphere in the arc furnace, after moving the alloy button ingot to the pouring station, arc is struck and the current is slowly increased to melt the button ingot. When the bottom alloy is completely melted and quickly drips into the mold directly below the station, a Ti alloy ingot is prepared.

[0081] The solidification microstructure diagram of the Ti-0.2B-0.2Tb alloy obtained in Example 3 is as follows Figure 3 shown. Metallographic microstructure observation was carried out using a stereomicroscope. Small cubes with dimensions of 15 mm×10 mm×5 mm were cut from the specimens using wire cutting, and then polished successively with 80#, 120#, 240#, 500#, 800#, 1000#, 1200# and 2000# SiC sandpapers until they were shiny. Subsequently, mechanical polishing was carried out, and the surface of the samples was etched using an etching solution for microstructure observation.

[0082] After testing, the average size of the equiaxed crystal grains of the alloy obtained in Example 3 was 340 μm.

[0083] Example 4

[0084] This example provides a Ti alloy for refining grains of solutes based on mixing enthalpy and solidification range and a preparation method thereof. The alloy is Ti 99 -B 0.5 -Tb 0.5 , and the specific preparation method includes the following steps:

[0085] Step 1: Design and select the solute pair elements for refining the grains of the Ti alloy and their addition contents according to the dual principles of mixing enthalpy and solidification range. Element A is boron, the addition content is 0.5 at.%, and the addition form is TiB 2 powder; Element D is terbium, the addition content is 0.5 at.%, and the addition form is Tb powder.

[0086] Among them, the mixing enthalpy of boron element and terbium element is -51 kJ / mol, the mixing enthalpy of titanium element and boron element is -58 kJ / mol, and the mixing enthalpy of titanium element and terbium element is 14 kJ / mol. The solidification range of adding 0.5 at.% boron element to titanium is 116 °C, and the solidification range of adding 0.5 at.% terbium element to titanium is 244 °C.

[0087] Step 2: Weigh the corresponding masses of Ti raw materials, TiB 99 -B 0.5 -Tb 0.5 (at.%, atomic percentage) components, and then put them into a melting crucible. Among them, the powder raw materials are placed in the middle of the Ti metal particles to prevent them from being blown away by the arc during melting. 2 The alloy raw materials were continuously subjected to multiple arc melting in an argon atmosphere, and stirring was carried out during the melting process to achieve uniform distribution of each element. After the melt solidified, a button ingot was obtained.

[0088] In the argon atmosphere, the alloy raw materials were continuously subjected to multiple arc melting, and stirring was carried out during the melting process to achieve uniform distribution of each element. After the melt solidified, a button ingot was obtained.

[0089] Step 3: Evacuate the arc furnace to less than 2×10 -2 Pa, and then backfill argon to about 5×104 Pa, repeat the operation 2 times. Then, under an argon atmosphere, the alloy raw materials are continuously subjected to arc melting 5 times. During the melting process, electromagnetic stirring is carried out to obtain a melt with uniform composition. After the metal melt is completely solidified, an alloy button ingot is obtained.

[0090] Among them, the melting current of the arc melting is 350 A, and the arc melting time is 3 minutes each time.

[0091] During arc melting, an eddy current magnetic field is applied for electromagnetic stirring, and the current intensity of the eddy current magnetic field is 10 A.

[0092] Step 4: Under the argon atmosphere in the arc furnace, after moving the alloy button ingot to the pouring station, arc is struck and the current is slowly increased to melt the button ingot. When the bottom alloy is completely melted and quickly drops into the mold directly below the station, a Ti alloy ingot is obtained.

[0093] A stereomicroscope is used for metallographic structure observation. A small cube with dimensions of 15 mm×10 mm×5 mm is cut from the sample by wire cutting, and is polished brightly in sequence with SiC sandpapers of 80#, 120#, 240#, 500#, 800#, 1000#, 1200# and 2000#. Subsequently, mechanical polishing is carried out, and the surface of the sample is corroded with the etching solution for structure observation.

[0094] After testing, the average size of the equiaxed crystal grains of the alloy obtained in Example 4 is 105 μm.

[0095] Comparative Example 1

[0096] This comparative example provides a preparation method of Ti, including the following steps:

[0097] In this comparative example, step 1 of Example 1 "Design and select solute pair elements and their addition contents for refining Ti alloy grains based on the dual principles of mixing enthalpy and solidification range" is changed to not adding solute elements A and D, and then a Ti alloy ingot is obtained according to the arc melting and drop casting processes of Example 1.

[0098] The solidification structure diagram of the obtained Ti alloy is as Figure 4 shown.

[0099] A stereomicroscope is used for metallographic structure observation. A small cube with dimensions of 15 mm×10 mm×5 mm is cut from the sample by wire cutting, and is polished brightly in sequence with SiC sandpapers of 80#, 120#, 240#, 500#, 800#, 1000#, 1200# and 2000#. Subsequently, mechanical polishing is carried out, and the surface of the sample is corroded with the etching solution for structure observation.

[0100] After testing, the average width and length of the columnar crystal grains of the alloy obtained in Comparative Example 1 were approximately 520 μm and 1760 μm, respectively.

[0101] Comparative Example 2

[0102] This comparative example provides a Ti alloy and a preparation method thereof. The alloy is Ti 99.7 -B 0.3 , and the specific preparation method includes the following steps:

[0103] Step 1: Weigh the corresponding masses of Ti raw materials and TiB 99.7 -B 0.3 (at.%, atomic percentage) components, and then place them in a melting crucible. Among them, the powder raw materials are placed in the middle of Ti metal particles to prevent them from being blown away by the arc during melting. 2

[0104] Among them, the mixing enthalpy of titanium element and boron element is -58 kJ / mol, and the solidification range of adding 0.3 at.% boron element to titanium is 120 °C.

[0105] Under an argon atmosphere, continuously carry out multiple arc melting on the alloy raw materials, and stir during the melting process to achieve uniform distribution of each element. After the melt solidifies, a button ingot is obtained.

[0106] Step 2: Evacuate the arc furnace to less than 2×10 -2 Pa, then backfill argon to about 5×10 4 Pa, and repeat the operation 2 times. Then, under an argon atmosphere, continuously carry out 5 arc melting on the alloy raw materials, and carry out electromagnetic stirring during the melting process to obtain a melt with uniform composition. After the metal melt is completely solidified, an alloy button ingot is obtained.

[0107] Among them, the melting current of the arc melting is 350 A, and the arc melting time is 3 minutes each time.

[0108] During arc melting, an eddy current magnetic field is applied for electromagnetic stirring, and the current intensity of the eddy current magnetic field is 10 A.

[0109] Step 3: Under the argon atmosphere in the arc furnace, after moving the alloy button ingot to the pouring station, arc ignition is carried out and the current is slowly increased to make the button ingot melt. When the bottom alloy is completely melted and quickly drips into the mold directly below the station, a Ti alloy ingot is obtained.

[0110] ​The metallographic structure was observed using a stereomicroscope. Small cubes with dimensions of 15 mm × 10 mm × 5 mm were cut from the specimens by wire cutting, and then polished brightly successively with 80#, 120#, 240#, 500#, 800#, 1000#, 1200# and 2000# SiC sandpapers. Subsequently, mechanical polishing was carried out, and the surface of the sample was etched with an etching solution for microstructure observation.

[0111] After testing, the average size of the equiaxed crystal grains of the alloy obtained in Comparative Example 2 was 800 μm.

[0112] Comparative Example 3

[0113] This comparative example provides a Ti alloy and its preparation method. The alloy is Ti 99.7 -Tb 0.3 , and the specific preparation method includes the following steps:

[0114] Step 1: Weigh the corresponding masses of Ti raw materials and Tb raw materials according to the Ti 99.7 -Tb 0.3 (at.%, atomic percentage) composition, and then put them into a melting crucible. Among them, the powder raw materials are placed in the middle of the Ti metal particles to prevent being blown away by the arc during melting.

[0115] Among them, the mixing enthalpy of titanium element and terbium element is 14 kJ / mol, and the solidification range of adding 0.3 at.% terbium element to titanium is 140 °C.

[0116] Under an argon atmosphere, the alloy raw materials were continuously subjected to multiple arc melting, and stirring was carried out during the melting process to achieve uniform distribution of each element. After the melt solidified, a button ingot was obtained.

[0117] Step 2: The arc furnace was evacuated to less than 2×10 -2 Pa, and then backfilled with argon to about 5×10 4 Pa, and the operation was repeated 2 times. Then, under an argon atmosphere, the alloy raw materials were continuously subjected to 5 arc melting, and electromagnetic stirring was carried out during the melting process to obtain a melt with uniform composition. After the metal melt was completely solidified, an alloy button ingot was obtained.

[0118] Among them, the melting current of the arc melting is 350 A, and the arc melting time is 3 minutes each time.

[0119] During arc melting, an eddy current magnetic field was applied for electromagnetic stirring, and the current intensity of the eddy current magnetic field is 10 A.

[0120] Step 3: Under the argon atmosphere in the arc furnace, after moving the alloy button ingot to the pouring station, an arc was struck and the current was slowly increased to melt the button ingot. When the alloy at the bottom was completely melted and quickly dripped into the mold directly below the station, a Ti alloy ingot was prepared.

[0121] The metallographic structure was observed using a stereomicroscope. Small cubes with dimensions of 15 mm × 10 mm × 5 mm were cut from the specimens by wire cutting, and then polished successively with 80#, 120#, 240#, 500#, 800#, 1000#, 1200#, and 2000# SiC sandpapers until shiny. Subsequently, mechanical polishing was carried out, and the surface of the sample was etched with an etching solution for microstructure observation.

[0122] After testing, the average size of the equiaxed grains of the alloy obtained in Comparative Example 3 was 870 μm.

[0123] From Figures 1-4 It can be seen that compared with the coarse columnar grains obtained in Comparative Example 1, the equiaxed grain structures obtained in Examples 2-4 were significantly refined, and were superior to the refinement effects of Comparative Examples 2 and 3 with the addition of the corresponding solute contents alone, achieving the purpose of refining the grains of Ti alloys with solutes based on the mixing enthalpy and solidification range.

[0124] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for designing solute-refined alloy structure based on mixing enthalpy and solidification range, characterized in that: The alloy is a ternary alloy Ti 100-2x -A x -D x , where x is 0.1 to 0.5, A and D are metal refining elements and non-metal refining elements; The mixing enthalpy of element A and element D is -45 to -65 kJ / mol, the mixing enthalpy of element Ti and element A is -120 to 15 kJ / mol, and the mixing enthalpy of element Ti and element D is -50 to 15 kJ / mol; the solidification range of the alloy structure is greater than 50°C; the solute distribution coefficients of element A and element D are both less than 1.

2. The method for designing solute-refined alloy structure based on mixing enthalpy and solidification range according to claim 1, characterized in that: The element A is boron, the element D is terbium, and the alloy is Ti 100-2x -B x -Tb x .

3. The method for designing solute-refined alloy structure based on mixing enthalpy and solidification range according to claim 1, characterized in that: The alloy is an equiaxed crystal ingot and has isotropy.

4. A preparation method for alloy structure refinement by designing solute based on mixing enthalpy and solidification range according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, according to Ti 100-2x -A x -D x Weigh Ti raw material, A raw material, and D raw material in a stoichiometric ratio, and then put these raw materials into a melting crucible; S2, arc melting the alloy raw materials under an argon atmosphere, stirring the alloy raw materials during the melting process to evenly distribute the elements, and allowing the melt to stand to cool and solidify after the melting is completed to obtain a button ingot; S3, drop-casting the button ingot under its own gravity to obtain a Ti alloy.

5. A preparation method for alloy structure refinement by designing solute based on mixing enthalpy and solidification range as claimed in claim 4, characterized in that: When the A element and the D element are non-metallic elements, they are added in the form of powders, and when placing the powder raw materials, they are surrounded by metal particles corresponding to other metal elements.

6. A method for preparing alloy structure by designing solute refinement based on mixing enthalpy and solidification range as claimed in claim 4, characterized in that: The Ti raw material is Ti metal particles, the A raw material is boride powder or boron powder, and the D raw material is terbium powder.

7. A preparation method for alloy structure refinement by designing solute based on mixing enthalpy and solidification range as claimed in claim 4, characterized in that: The stirring is achieved by applying an eddy current magnetic field to the molten metal during the smelting process, and the current used to generate the eddy current magnetic field does not exceed 15A; the smelting current applied by the arc smelting does not exceed 450A.

8. A method for preparing alloy structure by designing solute refinement based on mixing enthalpy and solidification range as claimed in claim 4, characterized in that: The arc melting and cooling and solidification after the melting are repeated for multiple times, at least 5 times.

9. A method for preparing alloy structure by designing solute refinement based on mixing enthalpy and solidification range as claimed in claim 4, characterized in that: The smelting time of each smelting is not less than 3 minutes.

10. A method for designing a solute-refined alloy structure, characterized in that: This is achieved by controlling the following conditions: The alloy is a ternary alloy Ti 100-2x -A x -D x , where x is 0.1 to 0.5, A and D are metal refining elements and non-metal refining elements; The mixing enthalpy of element A and element D is -45 to -65 kJ / mol, the mixing enthalpy of element Ti and element A is -120 to 15 kJ / mol, and the mixing enthalpy of element Ti and element D is -50 to 15 kJ / mol; the solidification range of the alloy structure is greater than 50°C; the solute distribution coefficients of element A and element D are both less than 1.

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