Wide-temperature-range and low-wear block composite lamellar multi-component alloy and preparation method thereof

Abstract

The invention provides a wide-temperature-range and low-abrasion block composite lamellar multi-element alloy and a preparation method thereof, and aims to solve the technical problems that a common multi-element AlCrCoNi alloy system is insufficient in hardness and poor in abrasion resistance in a high-temperature environment at present. According to the invention, electric arc melting is adopted for preparation, and the block lamellar multi-component alloy combining a hard phase (BCC) and a hard phase (L21) is obtained. And due to the hard-hard combined lamellar structure, the material has excellent high-temperature wear resistance and relatively high yield strength and hardness. Wherein when a load of 20N is applied, the wear rate of the multi-component alloy at 800 DEG C is as low as 4.04 * 10 <-7 > mm < 3 > / N.m.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material preparation, and particularly relates to a bulk composite laminated multi-alloy with wide-temperature range and low wear and a preparation method thereof. Background Art

[0002] Multi-alloy (also known as high-entropy alloy), as a new type of alloy material, has characteristics different from traditional alloys due to its unique composition design, such as high-entropy effect, lattice distortion effect, sluggish diffusion effect, cocktail effect, etc. These effects of multi-alloy enable it to exhibit excellent properties in many fields, including mechanical properties, corrosion resistance, thermal stability, etc., so it has broad application prospects in the fields of aerospace, industrial equipment, energy power, etc.

[0003] Friction and wear of metal materials are one of the important problems affecting the reliability and safety of mechanical equipment. The failure of metal components caused by wear will not only reduce product quality and cause economic losses, but may also cause major accidents. Therefore, the research and improvement of the wear resistance of metal materials are of great significance for industrial development, economic benefits and safety guarantee. Under wide-temperature range conditions, the wear mechanism of multi-alloy generally changes from abrasive wear dominated by mechanical properties to oxidative wear dominated by oxidation as the temperature increases. The common multi-alloy system of AlCrCoNi is difficult to balance its mechanical and oxidation properties under wide-temperature range, resulting in poor wear resistance under wide-temperature range. The specific reason is that at room temperature, due to its low hardness, serious abrasive wear will occur on the alloy surface, resulting in poor wear resistance. As the temperature increases, the hardness of the material further decreases, and in addition, the surface / subsurface microstructure changes due to oxidation, so its wear resistance will further decrease. In view of the complex load requirements under extreme service conditions in different fields, developing multi-alloy with good comprehensive mechanical properties and high-temperature wear resistance is the research focus of the metal material discipline. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problems of the common multi-alloy system of AlCrCoNi at present, such as insufficient hardness and poor wear resistance in high-temperature environment, and provide a bulk composite laminated multi-alloy with wide-temperature range and low wear and a preparation method thereof.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] A bulk composite laminated multi-alloy with wide-temperature range and low wear, characterized in that its expression is AlCr 1.7 Co 0.5 Ni 1.9Ti (i.e., composed of 16.4% Al, 27.9% Cr, 8.2% Co, 31.1% Ni, and 16.4% Ti by atomic percentage), is a two-phase lamellar eutectic multi-alloy composed of a BCC hard phase and an L21 hard phase. The two-phase lamella has a hardness exceeding 600 HV, with a significant increase in hardness. Also, according to the microscopic morphology of the friction test samples, no microcracks are observed, indicating that its hardness meets the requirements for alloy use. Additionally, when tested, the multi-alloy with the above atomic percentages has a wear rate as low as 4.04×10 -7 mm 3 / N·m.

[0007] The preparation method of the above-mentioned bulk composite lamellar multi-alloy with wide temperature range and low wear is characterized in that it includes the following steps:

[0008] S1 Raw material pretreatment:

[0009] S1.1 Grinding and polishing

[0010] The raw materials of Al, Cr, Co, Ni, and Ti are successively ground and polished to remove the oxide scale on the surface of the raw materials, obtaining metal raw materials with a smooth surface.

[0011] S1.2 Cleaning

[0012] The raw materials of Al, Cr, Co, Ni, and Ti after S1.1 grinding and polishing are ultrasonically cleaned using an organic solvent (such as an alcohol solution) (i.e., each raw material is separately placed in a container filled with an organic solvent for ultrasonic cleaning), removing the impurities attached to the surface of the raw materials, and then fully dried and separately placed in different specimen bags for standby.

[0013] S2 Batching:

[0014] According to the atomic percentages of the elements in the alloy, the Al, Cr, Co, Ni, and Ti after S1 pretreatment are weighed as alloy raw materials.

[0015] S3 Melting:

[0016] S3.1 The alloy raw materials weighed in S2 are successively placed from bottom to top into the crucible on the outer ring of the arc melting furnace in the order of Al, Cr, Co, Ni, and Ti (the placement of the metal raw materials here is based on the melting points, and considering the volatility of the elements, the elements that are not easily volatile are used to cover the elements that are easily volatile to maintain the precise ratio of each element in the multi-alloy as much as possible). Then, the pre-prepared titanium ingot is placed into the crucible in the center of the arc melting furnace, and the furnace door is closed.

[0017] S3.2 Turn on the mechanical pump to evacuate the arc melting furnace. After the vacuum degree is less than or equal to 5 MPa, turn on the molecular pump and continue to evacuate to 5×10 -3 MPa, then backfill with inert gas to -0.05 MPa; repeat this operation multiple times to ensure that the air in the arc melting furnace is exhausted. Although the vacuum environment has greatly reduced the oxygen content, filling with inert gas can further ensure that the alloy is not oxidized during the melting process. Argon, as a commonly used inert gas, does not react chemically with molten metal, so argon can be selected for backfilling. At the same time, in the case of filling with inert gas, the melt may be more likely to remain in contact with the electrode, which helps to stabilize the arc and the continuity of the melting process;

[0018] S3.3 Melting titanium ingots

[0019] Set the current to 100 - 200 A, the melting time to 3 - 5 min, and melt the titanium ingot 2 - 3 times repeatedly; since oxides, oils or processing residues may adhere to the surface of the titanium ingot, the first melting volatilizes or decomposes these contaminants through a high-temperature vacuum environment, thereby significantly reducing the impurity content and improving the purity of the titanium ingot, laying a foundation for subsequent melting. Remelting can further remove residual gases and non-metallic inclusions (such as oxides, nitrides);

[0020] After each melting is completed, observe the surface of the titanium ingot to ensure it is bright and free of oxidation. If oxidation occurs, repeat the operation in S3.2. If it is bright and free of oxidation, proceed to S3.4;

[0021] S3.4 Melting alloy raw materials

[0022] Set the current to 120 - 200 A, the melting time to 3 - 5 min. After the sample melting is completed and cooled, turn it over, and repeat melting 5 - 6 times, then cool with the furnace to obtain a composite laminated multi-alloy. If the current is set too large, the molten pool will be too deep, resulting in the crystallization direction tending to be horizontal, increasing the risk of porosity and composition segregation. At the same time, it may cause splashing and too thick ingot crown. If the current is too small, the molten pool will be too shallow, resulting in insufficient volatilization of gases and impurities, and easily generating subcutaneous pores or surface laminations. Therefore, the current is controlled within the aforementioned range;

[0023] During the repeated melting process, electromagnetic stirring is used to assist to ensure the uniformity of the composition and structure of the multi-alloy product. Of course, after the last melting, the molten pool can also be transferred to the suction casting crucible by a robotic arm. When the suction casting valve is started, the pressure in the furnace cavity drops suddenly to form a pressure difference with the copper mold cavity, and the liquid metal is instantly injected into the copper mold cavity. The copper mold circulates cooling water through the built-in spiral water channel to obtain the multi-alloy product with the corresponding shape.

[0024] Furthermore, in S1.1, the purity of the Al, Cr, Co, Ni, and Ti raw materials is higher than 99.99%;

[0025] Grinding is carried out using a grinding wheel; polishing is carried out using sandpaper;

[0026] In S1.2, the ultrasonic cleaning duration is 15 - 20 min.

[0027] Furthermore, in S2, an analytical balance is used to weigh the raw materials, and the error is controlled within ±0.001 g.

[0028] Furthermore, before S3.1, it is necessary to polish the arc tungsten electrode to be bright using a grinding wheel and install it in the arc melting furnace; it is necessary to dip a sterile cloth in alcohol, wipe the inner cavity of the arc melting furnace and dry it to ensure that there are no impurities and residues in the furnace.

[0029] Furthermore, in S3.2, this operation is repeated 2 - 3 times;

[0030] Furthermore, in S3.3, the current is set to 100 A; in S3.4, the current is set to 180 A.

[0031] Concept and principle of the present invention:

[0032] The existing multi - principal - element alloys generally have a microstructure combining hard and soft phases (such as FCC phase). Although a certain plasticity is retained, when the proportion of the FCC phase in the high - entropy alloy is too high, the wear rate still cannot meet the requirements of extreme working conditions. For example, the currently common multi - element AlCrCoNi alloy system has problems of insufficient hardness and poor high - temperature wear resistance. The research team of the present invention analyzed the reasons, which mainly lie in that: the microstructure of the AlCrCoNi alloy system is a hard BCC (B2) + soft FCC (L12) structure, and the soft - hard combined microstructure leads to certain limitations in its mechanical properties and wear resistance during service. Since the properties of materials are closely related to the microstructure, the research team of the present invention changed the conventional composite mode of the microstructure form, proposed to composite two hard phases in the form of lamellae, while improving the wear resistance, ensuring that it has a certain compressive plasticity; the construction of this composite lamellar phase structure can be achieved through element regulation.

[0033] The present invention designs multi - element alloys using the mixed enthalpy method. First, in combination with the melting points, interactions, and possible phases of elements, elements that can form a stable eutectic structure at the eutectic temperature are selected. Secondly, the total mixed enthalpy of the multi - element alloy is calculated using the binary mixed enthalpy data between the selected elements. Combining the atomic size difference and electron concentration, the temperature and phase composition of the eutectic reaction are optimized by adjusting the composition ratio. Using this design concept, a lamellar eutectic multi - element alloy with the combination of a hard phase (BCC) and a hard phase (L21) is prepared. Compared with the traditional eutectic multi - element alloy with the combination of a hard phase (BCC, B2) and a soft phase (FCC, L12), the microstructure of the combination of the hard - hard lamellae significantly improves the wear resistance of the material, and at the same time has comprehensive mechanical properties such as high hardness and high yield strength.

[0034] By adding Ti to the AlCrCoNi alloy system, the main reasons are as follows: Ti has the largest atomic radius in this system. After adding Ti, it will dissolve in the BCC solid solution, resulting in an increase in the lattice constant and lattice distortion. At the same time, in alloy design, by significantly increasing the proportion of Ti in the multi - principal - element alloy, the FCC (L12) soft phase completely disappears, promoting the formation of the L21 hard matrix phase. Elements such as Cr and Co have a certain promoting effect on the nucleation and growth of the BCC phase. The synergistic effect of the elements determines the final eutectic microstructure and the distribution of the two phases. The alloy system forms a lamellar structure with the combination of a hard phase (BCC) and a hard phase (L21). The combination of this hard - hard lamella significantly improves the strength, hardness, and wear resistance of the alloy. Secondly, the Ti element has a certain oxidation resistance. After adding Ti, it can improve the high - temperature oxidation resistance of the alloy, broaden the applicable temperature range, and enhance its wear resistance at high temperatures. In summary, in the wide temperature range from room temperature to 800 °C, the multi - element alloy designed by the present invention has good comprehensive mechanical properties and high - temperature wear resistance.

[0035] Advantages of the present invention:

[0036] 1. Aiming at the problems existing in the existing AlCrCoNi alloy system, such as insufficient hardness and poor high - temperature wear resistance, the present invention prepares a bulk composite lamellar multi - eutectic high - entropy alloy AlCr 1.7 Co 0.5 Ni 1.9 Ti by adding Ti to the hard - soft structure alloy system. The lamellae of this alloy are composed of a hard phase (BCC) and a hard phase (L21). This hard - hard combined lamellar structure significantly improves the high - temperature wear resistance, hardness, and yield strength of the multi - element alloy. Compared with the AlCrCoNi - based alloy with the combination of a hard phase (B2) and a soft phase (L12), the AlCr 1.7 Co 0.5 Ni 1.9 Ti multi - element alloy has a wear rate as low as 4.04×10-7 mm 3 / N·m, the hardness value reaches 633.88 HV, and the yield strength is 1774.96 MPa. Therefore, the wear resistance of the bulk composite laminate multi-element alloy designed through the above ideas is significantly improved, and it also has comprehensive mechanical properties such as high hardness and high yield strength at the same time.

[0037] 2. Through composition design, the present invention innovatively designs a multi-element eutectic high-entropy alloy with a laminate composite structure. This multi-element alloy is a hard-hard laminate structure composed of a hard phase (BCC) and a hard phase (L21). Utilizing the composite structure characteristics it possesses, it realizes good strength-plasticity matching and low wear in a wide temperature range under a large load. Therefore, it has broad application prospects in the field of engineering structures. The wide-temperature-range low-wear composite laminate multi-element alloy of the present invention not only provides a paradigm for the development and preparation of bulk wear-resistant alloys, but also provides an important reference for the preparation of multi-element alloy composite laminate coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 XRD diffraction patterns of the multi-element alloys of the examples (AlCr 1.7 Co 0.5 Ni 1.9 Ti) and comparative examples (AlNi 2.7 Cr 1.7 Co 0.7 ) of the present invention.

[0039] Figure 2 SEM images of the multi-element alloy of the example (AlCr 1.7 Co 0.5 Ni 1.9 Ti) of the present invention at different magnifications.

[0040] Figure 3 SEM images of the multi-element alloy of the comparative example (AlNi 2.7 Cr 1.7 Co 0.7 ) of the present invention at different magnifications.

[0041] Figure 4 Micro-Vickers hardness diagrams of the multi-element alloys of the examples (AlCr 1.7 Co 0.5 Ni 1.9 Ti) and comparative examples (AlNi 2.7 Cr 1.7 Co 0.7 ) of the present invention.

[0042] Figure 5 SEM images of the multi-element alloy of the example (AlCr 1.7 Co 0.5 Ni 1.9(Ti) and Comparative Example (AlNi 2.7 Cr 1.7 Co 0.7 ) Compressive stress-strain diagram of the multi-component alloy.

[0043] Figure 6 For the example of the present invention (AlCr 1.7 Co 0.5 Ni 1.9 (Ti) and Comparative Example (AlNi 2.7 Cr 1.7 Co 0.7 ) Wear rate data diagram of the multi-component alloy under a 5N load.

[0044] Figure 7 For the example of the present invention (AlCr 1.7 Co 0.5 Ni 1.9 (Ti) and Comparative Example (AlNi 2.7 Cr 1.7 Co 0.7 ) Wear rate data diagram of the multi-component alloy under a 20N load. Detailed implementation manners

[0045] The following further describes the content of the present invention in detail in conjunction with the accompanying drawings and specific examples:

[0046] Example 1:

[0047] This example discloses a bulk composite laminate multi-component alloy with wide temperature range and low wear, and its expression is AlCr 1.7 Co 0.5 Ni 1.9 Ti. The specific preparation method is as follows:

[0048] Step 1: Grind the raw materials of Al, Cr, Co, Ni, and Ti in turn with a grinding wheel and polish them with sandpapers of different grits to remove the oxide scale on the surface of the metal raw materials. The purity of the above metal raw materials is higher than 99.99%.

[0049] Step 2: Put the polished raw materials into different beakers respectively, add an appropriate amount of alcohol solution, and ultrasonically clean for 20 minutes to remove the impurities attached to the surface. After drying thoroughly, put them into different specimen bags for standby.

[0050] Step 3: Weigh the ingredients according to the atomic percentages (16.4% Al, 27.9% Cr, 8.2% Co, 31.1% Ni, 16.4% Ti). Each metal ingot is 50 g. Weigh 8.2 g of Al, 13.95 g of Cr, 4.1 g of Co, 15.55 g of Ni, and 8.2 g of Ti respectively with an analytical balance, and control the error within ±0.001 g.

[0051] Step 4: Polish the arc tungsten electrode until it is shiny using a grinding wheel and install it in the arc melting furnace. Dip a sterile cloth in alcohol, wipe the inner cavity of the arc melting furnace and let it dry. Put the alloy raw materials weighed in Step 3 into the crucible on the outer ring of the arc melting furnace in the order of Al, Cr, Co, Ni, and Ti from bottom to top, and then place the pre-prepared titanium ingot in the crucible at the center of the arc melting furnace. Close the furnace door.

[0052] Open the mechanical pump to evacuate the arc melting furnace. After the vacuum degree is less than or equal to 5 MPa, open the molecular pump and continue to evacuate to 5×10 -3 MPa, and then backfill argon to -0.05 MPa. Repeat the above operation 3 times to ensure that the air in the arc melting furnace is exhausted.

[0053] After filling with the protective gas, first melt the titanium ingot. Set the current to 100 A and the melting time to 5 min, and melt it repeatedly 3 times. Observe the surface of the titanium ingot after each melting to ensure it is shiny and free of oxidation. Subsequently, melt the alloy raw materials. Set the current to 180 A and the melting time to 5 min. After the sample is melted and cooled, turn it over and repeat melting 6 times to obtain a uniform microstructure, and cool it in the furnace. Finally, obtain a button-shaped AlCr 1.7 Co 0.5 Ni 1.9 Ti multi-element alloy.

[0054] Perform microstructure characterization, mechanical properties, and friction and wear tests on Example 1. For convenience of description, the subsequent multi-element alloy AlCr 1.7 Co 0.5 Ni 1.9 Ti is abbreviated as Co0.5 multi-element alloy, and the specific implementation methods and results are as follows:

[0055] Through X-ray diffraction (XRD) tests on the Co0.5 multi-element alloy, the phases present in the alloy were analyzed. The experiment used a D8 Discover A25 diffractometer from Bruker Corporation in the United States, with a Co-Kα target, a test range of 20 to 110°, and working voltage and current of 40 kV and 40 mA respectively. From Figure 1 the XRD pattern, it can be seen that the Co0.5 multi-element alloy is composed of two phases: the BCC hard phase and the L21 hard phase.

[0056] Use a FEI Helios G4 CX scanning electron microscope to characterize the microstructure of the Co0.5 multi-element alloy. Before the test, mechanically grind and polish the specimen on SiC sandpapers of 400#, 800#, 1200#, and 2000# to remove the cutting marks on the sample surface. Subsequently, mechanically polish for 30 min. The mechanical polishing solution is prepared by mixing SiO2 polishing solution, acetone, and pure water in a ratio of 7:2:1. From Figure 2It can be seen that the Co0.5 multi - element alloy consists of a lamellar structure composed of BCC hard phase and L21 hard phase, and the microstructure results are consistent with the XRD results.

[0057] The hardness value of the Co0.5 multi - element alloy was measured using a micro - Vickers hardness tester. Before the test, the samples were polished successively on SiC sandpapers of 400#, 800#, 1000#, and 2000# to remove the cutting marks on the sample surface. The parameters set for the hardness experiment were as follows: the external load was 500 gf, the dwell time was 5 s, each indentation was tested 4 times, and the micro - hardness value for each time was the average of the 4 tests. Each sample was tested 7 times. The highest and lowest values were removed from the 7 sets of measured data, and the average value of the remaining 5 sets of data was taken as the micro - hardness value of the specimen. The measured results are as Figure 4 shown, and the micro - hardness value of the Co0.5 multi - element alloy is 633.84 HV.

[0058] The compression properties of the Co0.5 multi - element alloy were tested using a tensile - compression integrated testing machine, and the test results are as Figure 5 shown, and the yield strength of the Co0.5 multi - element alloy is 1774.96 MPa.

[0059] The friction and wear properties of the Co0.5 multi - element alloy were tested using an Rtec ball - disk friction and wear tester (LMT - 5000). In Example 1, friction and wear experiments were carried out under normal temperature conditions (RT conditions), 200 °C temperature conditions, and 800 °C temperature conditions respectively. The counter - part used was Si3N4, and the applied loads were 5 N and 20 N respectively. The test results are as Figure 6 and Figure 7 shown.

[0060] Under normal temperature conditions, when applying loads of 5 N and 20 N, the wear rates of the Co0.5 multi - element alloy at normal temperature are both 4.36×10 -6 mm 3 / N·m, indicating that the wear resistance of the material is quite comparable under different loads at normal temperature.

[0061] Under 200 °C temperature conditions: when applying a load of 5 N, the wear rate of the Co0.5 multi - element alloy is 7.19×10 -5 mm 3 / N·m; when applying a load of 20 N, the wear rate of the Co0.5 multi - element alloy is 5.05×10 -5 mm 3 / N·m. Compared with the normal temperature conditions, the wear rates have all increased.

[0062] Under 800 °C temperature conditions: when applying a load of 5 N, the wear rate of the Co0.5 multi - element alloy is 3.26×10 -6 mm 3 / N·m; When a load of 20 N is applied, the wear rate of the Co0.5 multi - alloy is 4.04×10 -7 mm 3 / N·m. Compared with the room temperature and 200 °C conditions, the wear rate is significantly reduced, and better friction performance is presented under larger loads. The increase in the wear rate of the Co0.5 alloy under the test conditions of 200 °C is attributed to the fact that the alloy does not form an effective oxidation protection film, which is not sufficient to offset the thermoplastic deformation caused by the high - temperature softening of the alloy, resulting in an increase in the wear rate. When the temperature reaches 800 °C, the alloy with the directional composition design of this application forms a dense oxide layer, which can achieve the effect of reducing wear and anti - wear, thus effectively improving its friction and wear resistance. It can be seen that the components prepared with the multi - alloy of this application as the material can serve reliably at high temperatures.

[0063] Comparative Example 1:

[0064] This comparative example discloses a preparation method of an AlNi 2.7 Cr 1.7 Co 0.7 multi - alloy, and the specific operation steps are as follows:

[0065] Step 1: Grind the raw materials of Al, Cr, Co, and Ni in turn with a grinding wheel and polish them with sandpaper of different particle sizes to remove the oxide scale on the surface of the metal raw materials. The purity of the above - mentioned metal raw materials is higher than 99.99%.

[0066] Step 2: Put the ground raw materials into different beakers respectively, add an appropriate amount of alcohol solution, and ultrasonically clean for 20 min to remove the impurities attached to the surface. After fully drying, put them into different sample bags for standby.

[0067] Step 3: Weigh the materials according to the atomic percentages (16.4% Al, 44.3% Ni, 27.8% Cr, 11.5% Co). Each metal ingot is 50 g. Weigh 8.2 g of Al, 22.15 g of Ni, 13.9 g of Cr, and 5.75 g of Co respectively with an analytical balance, and control the error within ±0.001 g.

[0068] Step 4: Polish the arc tungsten electrode bright with a grinding wheel and install it in the arc melting furnace. Dip a sterile cloth in alcohol, wipe the inner cavity of the arc melting furnace and dry it. Put the alloy raw materials weighed in Step 3 into the crucible on the outer ring of the arc melting furnace in the order of Al, Cr, Co, and Ni from bottom to top, and then put the pre - prepared titanium ingot into the crucible in the center of the arc melting furnace, and close the furnace door.

[0069] Turn on the mechanical pump, evacuate the arc melting furnace. After the vacuum degree is less than or equal to 5 MPa, turn on the molecular pump and continue to evacuate to 5×10 -3After reaching MPa, backfill argon to -0.05 MPa. Repeat the above operation 3 times to ensure that the air in the arc melting furnace is exhausted.

[0070] After filling with the protective gas, start melting the titanium ingot. Set the current to 100 A and the melting time to 5 min, and melt repeatedly 3 times. Observe the surface of the titanium ingot after each melting to ensure it is bright and free of oxidation. Subsequently, melt the alloy raw materials. Set the current to 150 A and the melting time to 5 min. After the sample is melted and cooled, turn it over and repeat melting 6 times to obtain a uniform microstructure, and finally obtain AlNi 2.7 Cr 1.7 Co 0.7 multi-element alloy.

[0071] Perform microstructure characterization, mechanical properties, and friction and wear tests on Comparative Example 1. For the convenience of narration, the subsequent multi-element alloy AlNi 2.7 Cr 1.7 Co 0.7 is simply referred to as Co0.7 multi-element alloy, and the specific implementation methods and results are as follows:

[0072] Through X-ray diffraction (XRD) tests on the Co0.7 multi-element alloy, the phases present in the alloy were analyzed. The experiment used a D8 Discover A25 diffractometer from Bruker Corporation in the United States, with a Co-Kα target, a test range of 20 - 110°, and working voltage and current of 40 kV and 40 mA respectively. From Figure 1 the XRD pattern, it can be seen that the Co0.7 multi-element alloy is composed of two phases, the hard phase B2 and the soft phase FCC.

[0073] Use a FEI Helios G4 CX scanning electron microscope to perform microstructure characterization on the Co0.7 multi-element alloy. Before the test, mechanically polish the specimen on SiC sandpapers of 400#, 800#, 1200#, and 2000# to remove the cutting marks on the sample surface. Subsequently, perform mechanical polishing for 30 min. The mechanical polishing solution is prepared by mixing SiO2 polishing solution, acetone, and pure water in a ratio of 7:2:1. From Figure 3 it can be seen that the Co0.7 multi-element alloy is a lamellar structure composed of the hard phase BCC and the soft phase FCC, and the microstructure results are consistent with the XRD results.

[0074] The hardness of the Co0.7 multi - element alloy was measured using a micro - Vickers hardness tester. Before the test, the samples were polished successively on SiC sandpapers of 400#, 800#, 1000#, and 2000# to remove the cutting marks on the sample surface. The parameters set for the hardness experiment were as follows: the external load was 500 gf, the dwell time was 5 s, each indentation was tested 4 times, and the micro - hardness value for each time was the average of the 4 measurements. Each sample was tested 7 times. The highest and lowest values were removed from the 7 sets of measured data, and the average of the remaining 5 sets of data was taken as the micro - hardness value of the specimen. The measured results are as Figure 4 shown. The micro - hardness value of the Co0.7 multi - element alloy is 370.43 HV.

[0075] The compression properties of the Co0.7 multi - element alloy were tested using a tensile - compression integrated testing machine. The test results are as Figure 5 shown. The yield strength of the Co0.7 multi - element alloy is 783.84 MPa.

[0076] The friction and wear properties of the Co0.7 multi - element alloy were tested using an Rtec ball - on - disk friction and wear tester (LMT - 5000). Comparative example 1 carried out friction and wear experiments under normal temperature conditions (RT conditions), 200 °C temperature conditions, and 800 °C temperature conditions respectively. The counter - part used was Si3N4, and the applied loads were 5 N and 20 N respectively. The test results are as Figure 6 and Figure 7 shown.

[0077] Under normal temperature conditions, when a load of 5 N was applied, the wear rate of the Co0.7 multi - element alloy was 6.54×10 -5 mm 3 / N·m; when a load of 20 N was applied, the wear rate of the Co0.7 multi - element alloy was 1.74×10 -5 mm 3 / N·m. Compared with the Co0.5 alloy, the Co0.7 multi - element alloy has a higher wear rate and poorer wear resistance at normal temperature.

[0078] Under 200 °C temperature conditions: when a load of 5 N was applied, the wear rate of the Co0.7 multi - element alloy was 4.58×10 -4 mm 3 / N·m; when a load of 20 N was applied, the wear rate of the Co0.7 multi - element alloy was 1.31×10 -4 mm 3 / N·m. Compared with normal temperature conditions, the wear rate has increased, and its wear rate is still higher than that of the Co0.5 alloy.

[0079] Under 800 °C temperature conditions: when a load of 5 N was applied, the wear rate of the Co0.7 multi - element alloy was 6.54×10 -5 mm 3 / N·m; When a load of 20 N is applied, the wear rate of the Co0.7 multi - alloy is 3.19×10 -5 mm 3 / N·m. Compared with the temperature condition of 200 °C, the wear rate has increased, and its wear rate is still higher than that of the Co0.5 alloy.

[0080] By comparing the wear rates of the Co0.7 multi - alloy and the Co0.5 multi - alloy at different temperatures and different loads, it can be seen that the Co0.5 multi - alloy shows better wear resistance. Moreover, under the condition of maintaining a certain plasticity, the strength of the Co0.5 multi - alloy is higher than that of the Co0.7 multi - alloy. According to the compression test results, the plasticity of the Co0.5 multi - alloy is also significantly higher than that of the Co0.7 multi - alloy.

[0081] In summary, compared with the Co0.7 multi - alloy, the Co0.5 multi - alloy obtains a eutectic lamellar structure combined with the hard phase (BCC) and the hard phase (L21) by adding Ti. Compared with the eutectic structure combined with the soft phase (FCC) and the hard phase (BCC), the hard - hard combined lamellar structure significantly improves the hardness, yield strength and high - temperature wear resistance of the material.

[0082] Example 2

[0083] The difference from Example 1 is that:

[0084] After filling with the protective gas, first melt the titanium ingot, set the current to 200 A, the melting time to 2 min, and melt it repeatedly 2 times. Observe the surface of the titanium ingot after each melting to ensure it is bright and oxide - free. Subsequently, melt the alloy raw materials, set the current to 120 A, the melting time to 5 min. After the sample is melted and cooled, turn it over and repeat melting 6 times to obtain a uniform organizational structure. After the last melting, transfer the molten pool to the suction casting crucible by the robotic arm. When starting the suction casting valve, the pressure in the furnace cavity drops suddenly to form a pressure difference with the copper mold cavity, and the liquid metal is instantly injected into the 90 mm×10 mm×5 mm copper mold cavity. The copper mold circulates cooling water through the built - in spiral water channel. The melting result shows that the alloy structure still maintains the same hard - hard lamellar composite structure as in Example 1.

[0085] Example 3

[0086] The difference from Example 1 is that:

[0087] After filling with protective gas, first melt the titanium ingot with the current set at 150 A and the melting time of 3 min, and melt it repeatedly for 3 times. Observe the surface of the titanium ingot after each melting to ensure it is bright and free of oxidation. Subsequently, melt the alloy raw materials with the current set at 200 A and the melting time of 3 min. After the sample is melted and cooled, turn it over and repeat melting 5 times to obtain a uniform microstructure. After the last melting, transfer the molten pool to the suction casting crucible by a robotic arm. When the suction casting valve is started, the pressure in the furnace cavity drops suddenly to form a pressure difference with the copper mold cavity, and the liquid metal is instantly injected into the copper mold cavity of 90 mm × 10 mm × 10 mm. The copper mold circulates cooling water through the built-in spiral water channel. The melting result shows that the alloy structure still maintains the same hard layer composite structure as that in Example 1.

[0088] Perform mechanical property and friction and wear tests on the multi-element alloys prepared in Example 2 and Example 3. Compared with Comparative Document 1, the hardness, yield strength, and high-temperature wear resistance of the materials are all improved.

[0089] As described above, it is only the specific implementation manners of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A bulk composite laminated multi-alloy with wide temperature range and low wear, characterized in that: Its expression is AlCr 1.7 Co 0.5 Ni 1.9 Ti, which is a two-phase lamellar eutectic multi-alloy combining a BCC hard phase and an L21 hard phase.

2. The bulk composite laminate multi - element alloy with wide - temperature - range and low wear according to claim 1, characterized in that: When a load of 20 N is applied, the wear rate of the multi-component alloy is as low as 4.04×10 -7 mm 3 / N·m.

3. The preparation method of the bulk composite laminated multi - element alloy with wide temperature range and low wear as described in claim 1, characterized in that, It includes the following steps: S1 Raw material pretreatment: S1.1 Grinding and polishing The raw materials of Al, Cr, Co, Ni, and Ti are successively ground and polished. S1.2 Cleaning The raw materials of Al, Cr, Co, Ni, and Ti after grinding and polishing in S1.1 are ultrasonically cleaned with organic solvents respectively, and then fully dried for standby. S2 Batching: According to the atomic percentages of each element in the alloy, the Al, Cr, Co, Ni, and Ti after pretreatment in S1 are weighed as alloy raw materials. S3 Melting: S3.1 The alloy raw materials weighed in S2 are sequentially placed from bottom to top into the crucible on the outer ring of the arc melting furnace in the order of Al, Cr, Co, Ni, and Ti, and then the pre - prepared titanium ingot is placed into the crucible in the center of the arc melting furnace, and the furnace door is closed. S3.2 Turn on the mechanical pump to evacuate the arc melting furnace. After the vacuum degree is less than or equal to 5 MPa, turn on the molecular pump and continue to evacuate until it reaches 5×10 -3 MPa, and then backfill with inert gas to -0.05 MPa; Repeat this operation multiple times to ensure that the air in the arc melting furnace is exhausted. S3.3 Melting the titanium ingot The current is set to 100 - 200 A, the melting time is 3 - 5 min, and the titanium ingot is repeatedly melted 2 - 3 times. After each melting, observe the surface of the titanium ingot to ensure it is bright and non - oxidized. If oxidation occurs, return to S3.

2. S3.4 Melting the alloy raw materials The current is set to 120 - 200 A, the melting time is 3 - 5 min. After the sample is melted and cooled, turn it over, and repeat melting 5 - 6 times to obtain the composite laminate multi - element alloy. During the repeated melting process, electromagnetic stirring is used for assistance.

4. The preparation method of the bulk composite laminate multi - element alloy with wide - temperature - range and low wear according to claim 3, characterized in that: In S1.1, the purities of the raw materials of Al, Cr, Co, Ni, and Ti are all higher than 99.99%; grinding is carried out using a grinding wheel; polishing is carried out using sandpaper. In S1.2, the ultrasonic cleaning duration is 15 - 20 min.

5. The preparation method of the bulk composite laminate multi - element alloy with wide - temperature - range and low wear according to claim 3 or 4, characterized in that: In S2, the batching error is controlled within ±0.001 g.

6. The preparation method of the bulk composite laminate multi - element alloy with wide - temperature - range and low wear according to claim 5, characterized in that: Before S3.1, the arc tungsten electrode needs to be ground bright using a grinding wheel and installed in the arc melting furnace; a sterile cloth is used to dip alcohol to wipe the inner cavity of the arc melting furnace and dry it.

7. The preparation method of the bulk composite laminate multi - element alloy with wide - temperature - range and low wear according to claim 6, characterized in that: In S1.2, the organic solvent is alcohol; In S3.2, repeat this operation 2 - 3 times.

8. The preparation method of the bulk composite laminate multi - element alloy with wide - temperature - range and low wear according to claim 7, characterized in that: In S3.3, the current is set to 100 A; In S3.4, the current is set to 180 A.

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