Co-free CrxNiyAlz eutectic medium-entropy alloy and preparation method thereof

Abstract

The Co-free type CrxNiyAlz (x is greater than or equal to 1.5 and less than or equal to 2.5, y is greater than or equal to 1.5 and less than or equal to 2.5, and z is greater than or equal to 0.5 and less than or equal to 1.5) eutectic medium-entropy alloy, the microscopic structure of the Co-free type CrxNiyAlz eutectic medium-entropy alloy is a chrysanthemum-shaped eutectic structure composed of a BCC phase and a B2 phase, and the Co-free type CrxNiyAlz eutectic medium-entropy alloy has the advantages of excellent comprehensive mechanical properties and low cost, is suitable for large-scale production and has high engineering application value; according to the preparation method, pre-prepared metal raw materials are smelted through a vacuum smelting technology, the alloy is obtained through direct solidification forming, and the alloy production process is simple.

Description

Technical Field

[0001] The invention belongs to the technical field of medium entropy alloys and specifically relates to a Co-free Cr x Ni y Al z Eutectic medium-entropy alloy and method for preparing the same. Background Art

[0002] Multi-principal eutectic alloy is a new type of structural material. Compared with traditional alloys, multi-principal eutectic alloy has good strength-toughness matching. At the same time, multi-principal eutectic alloy has good casting processability and is easy to quickly form large-sized complex parts by solidification. Therefore, it has good application potential in aerospace, rail transportation, energy and chemical industries, and has become a research hotspot in the field of metal structural materials in recent years. Lu et al. reported the eutectic high entropy alloy AlCoCrFeNi 2.1 , with a compressive strength of 1265MPa and a fracture strain of 10.4%; Jiang et al. obtained the eutectic medium entropy alloy AlCrFeNi by adjusting the alloy composition, with a yield strength of 1040MPa and a Vickers hardness of 423HV; Jin et al. reported the eutectic high entropy alloy CrFeNi2Al, with a compressive strength of up to 1357MPa, while the compressive strain was maintained at 6%, with good strength and toughness matching. Although the reported multi-principal eutectic alloys have good mechanical properties, the alloy design often contains rare and precious metals such as Co, resulting in high alloy costs, which seriously hinders its large-scale engineering application; at the same time, with the upgrading of industry and the development of equipment, more and more stringent application requirements are put forward for high-performance metal structural materials, and the performance parameters of existing multi-principal eutectic alloys still have room for further improvement. Summary of the invention

[0003] The present invention aims to provide a Co-free Cr x Ni y Al z Eutectic medium entropy alloy and preparation method thereof, Cr x Ni y Al z Eutectic medium-entropy alloys have excellent comprehensive mechanical properties and low cost advantages, making them suitable for large-scale production.

[0004] The present invention is achieved through the following technical solutions:

[0005] A Co-free Cr x Ni y Al z Eutectic medium entropy alloy, chemical formula is Cr x Ni y Al z, where 1.5≤x≤2.5, 1.5≤y≤2.5, 0.5≤z≤1.5.

[0006] Preferably, the Cr x Ni y Al z The microstructure is a daisy-shaped eutectic BCC / B2.

[0007] A Co-free Cr x Ni y Al z The preparation method of the eutectic medium entropy alloy comprises the following steps:

[0008] S1: According to Cr x Ni y Al z , where: 1.5≤x≤2.5, 1.5≤y≤2.5, 0.5≤z≤1.5 Weigh pure Cr, Ni and Al metal elements;

[0009] S2: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metals in one water-cooled crucible in the order of melting point from low to high, and place metal Ti in the other water-cooled crucible. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa and then stir, while stirring, arc melting is performed, and after cooling, an alloy ingot is obtained;

[0010] S3: After the alloy ingot is turned over, it is remelted by arc, and the remelting is repeated 3 to 5 times, and the furnace is cooled to room temperature to obtain Cr x Ni y Al z Eutectic medium entropy alloy.

[0011] Furthermore, the step S1 further comprises washing the Cr, Ni and Al metal single substance raw materials in anhydrous ethanol and then drying them to obtain pure Cr, Ni and Al metal single substances.

[0012] This application has the following beneficial effects:

[0013] (1) Cr provided by this application x Ni y Al z The eutectic medium entropy alloy is prepared using conventional cheap metal raw materials Cr, Ni and Al. The alloy does not contain rare and precious Co, so Cr x Ni y Al zEutectic medium-entropy alloys have the advantage of low cost, are suitable for large-scale production, and have high engineering application value;

[0014] (2) This application uses vacuum melting technology to melt pre-configured metal raw materials, and Cr can be quickly obtained by direct solidification molding. x Ni y Al z Eutectic medium entropy alloy, the alloy production process is simple, the alloy microstructure is daisy-shaped eutectic BCC / B2, and it has excellent comprehensive mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The XRD spectrum of the Cr2Ni2Al eutectic medium-entropy alloy prepared in Example 1 of the present invention;

[0016] Figure 2 This is a low-magnification SEM image of the Cr2Ni2Al eutectic medium-entropy alloy prepared in Example 1 of the present invention;

[0017] Figure 3 This is a high-magnification SEM image of the Cr2Ni2Al eutectic medium-entropy alloy prepared in Example 1 of the present invention;

[0018] Figure 4 This is the room temperature compressive stress-strain curve of the Cr2Ni2Al eutectic medium-entropy alloy prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0020] A Co-free Cr x Ni y Al z Eutectic medium entropy alloy, chemical formula is Cr x Ni y Al z , where 1.5≤x≤2.5, 1.5≤y≤2.5, 0.5≤z≤1.5. Since Cr and Ni have similar atomic radii and their formation enthalpies are close to 0, they are easy to form a disordered solid solution BCC phase. In contrast, Al and Ni have large differences in atomic size and their formation enthalpies are relatively negative, so they are easy to form an intermetallic compound B2 phase. Therefore, a chrysanthemum-shaped eutectic structure composed of a BCC phase and a B2 phase can be obtained by alloy solidification.

[0021] The embodiments of the present application select Cr flakes with a purity of 99.95%, Ni particles with a purity of 99.95%, and Al blocks with a purity of 99.95% as the Cr, Ni, and Al metal single substance raw materials.

[0022] Example 1

[0023] A method for preparing a Co-free Cr2Ni2Al eutectic medium entropy alloy, the specific steps are as follows:

[0024] S1: Put the Cr, Ni and Al metal single substance raw materials into anhydrous ethanol and clean them by ultrasonic wave for 15 minutes, and then blow dry them with a hair dryer to obtain pure Cr, Ni and Al metal single substances;

[0025] S2: weigh pure Cr, Ni and Al metal elements in a molar ratio of 2:2:1;

[0026] S3: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metal elements in one water-cooled crucible in the order of melting point from low to high. Place metal Ti in the other water-cooled crucible to remove residual oxygen in the furnace. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa, then start electromagnetic stirring, and perform arc melting for 4 minutes while electromagnetic stirring, and obtain the alloy ingot after cooling;

[0027] S4: After the alloy ingot is turned over, it is remelted by arc for 4 minutes, and the remelting is repeated 5 times. The ingot is cooled to room temperature with the furnace to obtain a Cr2Ni2Al eutectic medium-entropy alloy.

[0028] The Cr2Ni2Al eutectic medium entropy alloy was analyzed by X-ray diffractometer with a scanning angle of 20-90° and a scanning speed of 4° / min. Figure 1 The XRD pattern shown in the figure shows that it contains B2 and BCC phases.

[0029] The Cr2Ni2Al eutectic medium entropy alloy was observed using a Czech TESCAN MIRA LMS scanning electron microscope. Figure 2 and Figure 3 As shown, the microstructure is a eutectic structure composed of B2 phase and BCC phase.

[0030] Two test samples were taken from the Cr2Ni2Al eutectic medium entropy alloy, namely sample 1 and sample 2, and the compression mechanical properties were tested at room temperature using a UTM5105 universal mechanical testing machine. The results are as follows: Figure 4As shown in Table 1, it can be seen from Table 1 that the compressive strength of the Cr2Ni2Al eutectic medium-entropy alloy is 3091.37MPa, and the fracture strain is 23.19%. After origin treatment, it is found that its room temperature yield strength is 1424.31MPa. It can be seen that the prepared Cr2Ni2Al eutectic medium-entropy alloy has good strength-toughness matching and comprehensive mechanical properties.

[0031] Table 1 Compression performance test parameters of Cr2Ni2Al eutectic medium entropy alloy

[0032]

[0033] Example 2

[0034] A Co-free Cr 1.5 Ni 1.5 Al 0.5 The preparation method of the eutectic medium entropy alloy includes the following specific steps:

[0035] S1: Put the Cr, Ni and Al metal single substance raw materials into anhydrous ethanol and clean them by ultrasonic wave for 15 minutes, and then blow dry them with a hair dryer to obtain pure Cr, Ni and Al metal single substances;

[0036] S2: Weigh pure Cr, Ni and Al metal elements in a molar ratio of 3:3:1;

[0037] S3: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metal elements in one water-cooled crucible in the order of melting point from low to high. Place metal Ti in the other water-cooled crucible to remove residual oxygen in the furnace. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa, then start electromagnetic stirring, and perform arc melting for 3 minutes while electromagnetic stirring, and obtain the alloy ingot after cooling;

[0038] S4: After the alloy ingot is turned over, it is remelted by arc for 3 minutes, and the remelting is repeated 3 times, and the ingot is cooled to room temperature with the furnace to obtain Cr 1.5 Ni 1.5 Al 0.5 Eutectic medium entropy alloy.

[0039] Example 3

[0040] A Co-free Cr 2.5 Ni 2.5 Al 1.5 The preparation method of the eutectic medium entropy alloy includes the following specific steps:

[0041] S1: Put the Cr, Ni and Al metal single substance raw materials into anhydrous ethanol and clean them by ultrasonic wave for 15 minutes, and then blow dry them with a hair dryer to obtain pure Cr, Ni and Al metal single substances;

[0042] S2: Weigh pure Cr, Ni and Al metal elements in a molar ratio of 5:5:3;

[0043] S3: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metal elements in one water-cooled crucible in the order of melting point from low to high. Place metal Ti in the other water-cooled crucible to remove residual oxygen in the furnace. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa, then start electromagnetic stirring, and perform arc melting for 5 minutes while electromagnetic stirring, and obtain the alloy ingot after cooling;

[0044] S4: After the alloy ingot is turned over, it is remelted by arc for 5 minutes, and the remelting is repeated 4 times, and the ingot is cooled to room temperature with the furnace to obtain Cr 2.5 Ni 2.5 Al 1.5 Eutectic medium entropy alloy.

[0045] Example 4

[0046] A Co-free Cr 1.8 Ni 1.8 Al 0.8 The preparation method of the eutectic medium entropy alloy includes the following specific steps:

[0047] S1: Put the Cr, Ni and Al metal single substance raw materials into anhydrous ethanol and clean them by ultrasonic wave for 15 minutes, and then blow dry them with a hair dryer to obtain pure Cr, Ni and Al metal single substances;

[0048] S2: Weigh pure Cr, Ni and Al metal elements in a molar ratio of 9:9:4;

[0049] S3: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metal elements in one water-cooled crucible in the order of melting point from low to high. Place metal Ti in the other water-cooled crucible to remove residual oxygen in the furnace. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa, then start electromagnetic stirring, and perform arc melting for 4 minutes while electromagnetic stirring, and obtain the alloy ingot after cooling;

[0050] S4: After the alloy ingot is turned over, it is remelted by arc for 4 minutes, and the remelting is repeated 3 times, and the ingot is cooled to room temperature with the furnace to obtain Cr 1.8 Ni 1.8 Al 0.8 Eutectic medium entropy alloy.

[0051] Example 5

[0052] A Co-free Cr 2.3 Ni 2.3 Al 1.3 The preparation method of the eutectic medium entropy alloy includes the following specific steps:

[0053] S1: Put the Cr, Ni and Al metal single substance raw materials into anhydrous ethanol and clean them by ultrasonic wave for 15 minutes, and then blow dry them with a hair dryer to obtain pure Cr, Ni and Al metal single substances;

[0054] S2: Weigh pure Cr, Ni and Al metal elements in a molar ratio of 2.3:2.3:1.3;

[0055] S3: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metal elements in one water-cooled crucible in the order of melting point from low to high. Place metal Ti in the other water-cooled crucible to remove residual oxygen in the furnace. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa, then start electromagnetic stirring, and perform arc melting for 3 minutes while electromagnetic stirring, and obtain the alloy ingot after cooling;

[0056] S4: After the alloy ingot is turned over, it is remelted by arc for 3 minutes, and the remelting is repeated 4 times, and the ingot is cooled to room temperature with the furnace to obtain Cr 2.3 Ni 2.3 Al 1.3 Eutectic medium entropy alloy.

[0057] Example 6

[0058] A Co-free Cr2Ni 1.5 The preparation method of Al eutectic medium entropy alloy comprises the following specific steps:

[0059] S1: Put the Cr, Ni and Al metal single substance raw materials into anhydrous ethanol and clean them by ultrasonic wave for 15 minutes, and then blow dry them with a hair dryer to obtain pure Cr, Ni and Al metal single substances;

[0060] S2: Weigh pure Cr, Ni and Al metal elements in a molar ratio of 2:1.5:1;

[0061] S3: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metal elements in one water-cooled crucible in the order of melting point from low to high. Place metal Ti in the other water-cooled crucible to remove residual oxygen in the furnace. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa, then start electromagnetic stirring, and perform arc melting for 5 minutes while electromagnetic stirring, and obtain the alloy ingot after cooling;

[0062] S4: After the alloy ingot is turned over, it is remelted by arc for 5 minutes, and the remelting is repeated 5 times, and the ingot is cooled to room temperature with the furnace to obtain Cr2Ni 1.5 Al eutectic medium entropy alloy.

[0063] The above contents are further detailed descriptions of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these inventions. For ordinary technicians in the technical field of the present invention, without departing from the concept of the present invention, they can also make several simple deductions or substitutions, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A Co-free Cr x Ni y Al z Eutectic medium entropy alloy, characterized by: The chemical formula is Cr x Ni y Al z , where 1.5≤x≤2.5, 1.5≤y≤2.5, 0.5≤z≤1.

5.

2. A Co-free Cr-2O3 according to claim 1 x Ni y Al z Eutectic medium entropy alloy, characterized in that The Cr x Ni y Al z The microstructure is a daisy-shaped eutectic BCC / B2.

3. A Co-free Cr2O3 as claimed in claim 1 or 2 x Ni y Al z A method for preparing a eutectic medium entropy alloy, characterized in that: The following steps are involved: S1: According to Cr x Ni y Al z , where: 1.5≤x≤2.5, 1.5≤y≤2.5, 0.5≤z≤1.5 Weigh pure Cr, Ni and Al metal elements; S2: Prepare two water-cooled crucibles and place them in a non-consumable arc melting furnace. Place pure Cr, Ni and Al metals in one water-cooled crucible in the order of melting point from low to high, and place metal Ti in the other water-cooled crucible. Then, repeatedly evacuate the non-consumable arc melting furnace until the vacuum degree of the furnace body reaches 6×10 -3 Pa, and then fill the non-consumable arc melting furnace with high-purity argon gas, control the gas pressure in the furnace to maintain at 0.05Pa and then stir, while stirring, arc melting is performed, and after cooling, an alloy ingot is obtained; S3: After the alloy ingot is turned over, it is remelted by arc, and the remelting is repeated 3 to 5 times, and the furnace is cooled to room temperature to obtain Cr x Ni y Al z Eutectic medium entropy alloy.

4. A Co-free Cr-2O3 according to claim 3 x Ni y Al z A method for preparing a eutectic medium entropy alloy, characterized in that: The step S1 further comprises washing the Cr, Ni and Al metal single substance raw materials in anhydrous ethanol and then drying them to obtain pure Cr, Ni and Al metal single substances.

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