Co-free Cr2FeNiNb x Cohesive entropy alloy and method of making same

Abstract

The application discloses a Co-free Cr2FeNiNb x eutectic entropy alloy and a preparation method thereof, which comprises Cr, Fe, Ni and Nb, and the molar ratio of Cr, Fe, Ni and Nb is 2:1:1:x, wherein 0.2 x eutectic entropy alloy, and the preparation method is simple and easy to control. x eutectic entropy alloy, and the preparation method is simple and easy to control.

Description

TECHNICAL FIELD

[0001] The present application relates to a medium-entropy alloy, in particular to a Co-free Cr2FeNiNb x eutectic medium-entropy alloy and a preparation method thereof. BACKGROUND

[0002] Medium-entropy alloys have good mechanical, physical and chemical properties such as high strength, high hardness, high wear resistance, high corrosion resistance and high temperature stability, and have excellent application potential in the engineering field. Single-phase medium-entropy alloys are mainly in solid solution structure, and have poor fluidity and castability. During the solidification process, different forms of metallurgical defects such as macro / micro-segregation, porosity or shrinkage holes are easily generated, which seriously affect the production quality of the ingot. At the same time, single-phase solid solution type medium-entropy alloys are difficult to balance the strength and toughness indexes. For example, the single-phase BCC medium-entropy alloy has good strength, but its toughness is poor; while the single-phase FCC medium-entropy alloy has good toughness, but its strength is low. Through reasonable composition design to form a eutectic structure, not only the strength and toughness matching problem of the single-phase alloy can be solved to obtain excellent comprehensive mechanical properties, but also the poor castability and metallurgical defects such as porosity and shrinkage holes of the single-phase alloy can be solved, thereby meeting the industrial production and actual application of the alloy.

[0003] At present, CoCrFeNi-based eutectic high-entropy alloys have attracted extensive research at home and abroad due to their excellent mechanical properties. Jiang et al. reported a eutectic high-entropy alloy CoCrFeNiTa 0.4 , which is composed of FCC phase and Laves phase, and has a fracture strength of 2290 MPa and a compression strain of 22.6%, and has good strength and toughness matching; Jiang and Chandd et al. reported a eutectic high-entropy alloy CoCrFeNiNb 0.45 , which has a fine and regular lamellar FCC / Laves structure, and the fracture strength of the alloy is 2200 MPa and the compression strain is 17.5%; Ye et al. reported a eutectic medium-entropy alloy CoCrFeNi-Nb6Ta4, and the room temperature fracture strength of the alloy is 2401 MPa and the compression strain is 30%. Although the above reported eutectic high-entropy alloys have excellent mechanical properties, these alloys contain expensive and rare Co element, which leads to high cost of the alloy, which seriously limits the industrial application of this kind of alloy. Therefore, on the basis of ensuring excellent performance, it is a key problem to develop a Co-free eutectic medium-entropy alloy. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a Co-free Cr2FeNiNb x eutectic medium-entropy alloy and a preparation method thereof, which not only prepares a Cr2FeNiNb xThe eutectic entropy alloy is simple in preparation method and easy to control.

[0005] In order to achieve the above-mentioned purpose, the following technical solutions are adopted:

[0006] A Co-free Cr2FeNiNb x The eutectic entropy alloy is simple in preparation method and easy to control.

[0007] Further, the eutectic entropy alloy includes a lamellar FCC / Laves eutectic and an irregular BCC / Laves eutectic.

[0008] A Co-free Cr2FeNiNb x The preparation method of the eutectic entropy alloy comprises the following steps:

[0009] Step 1, pure Cr, Fe, Ni and Nb metal elements are weighed according to a molar ratio of 2:1:1:x, wherein 0.2

[0010] Step 2, the pure Cr, Fe, Ni and Nb metal elements are sequentially placed in a water-cooled crucible in a non-consumable arc melting furnace according to the order of melting point from low to high, vacuum is repeatedly drawn on the non-consumable arc melting furnace and argon is injected, then arc is repeatedly melted, and a Co-free Cr2FeNiNb x eutectic entropy alloy is obtained after cooling to room temperature.

[0011] Further, the step 1 further comprises placing the Cr, Fe, Ni and Nb metal element raw materials in anhydrous ethanol respectively, cleaning by ultrasonic wave for 15-20 minutes, and drying by a hair dryer to obtain the pure Cr, Fe, Ni and Nb metal elements.

[0012] Further, the Cr, Fe, Ni and Nb metal element raw materials are Cr pieces with a purity of 99.95%, Fe particles with a purity of 99.95%, Ni particles with a purity of 99.95% and Nb blocks with a purity of 99.95%.

[0013] Further, the non-consumable arc melting furnace in the step 2 has at least two water-cooled crucibles, one of which is used to place the pure Cr, Fe, Ni and Nb metal elements, and the other of which is used to place a metal Ti element for removing residual oxygen in the furnace.

[0014] Further, the step 2 repeatedly draws vacuum on the non-consumable arc melting furnace to a vacuum degree of 3×10 -3 ~ 6×10 -3 Pa in the furnace body.

[0015] Further, the step 2 repeatedly vacuums and injects argon into the non-consumable arc furnace, and the internal pressure of the furnace body is 0.05 Pa.

[0016] Further, the step 2 repeatedly melts the Cr, Fe, Ni and Nb metal elements by using the arc, and the process is as follows: the Cr, Fe, Ni and Nb metal elements are first melted by using the arc for 4-5 min, the alloy ingot is obtained after cooling, the alloy ingot is turned over, and the arc is used again to remelt the alloy ingot for 4-5 min, and the above process is repeated for 5 times, and the furnace is cooled to room temperature, and the Co-free Cr2FeNiNb x eutectic entropy alloy.

[0017] Compared with the prior art, the present application has the following technical effects:

[0018] The chemical formula of the entropy alloy designed in the present application is Cr2FeNiNb x , wherein 0.2

[0019] The present application uses the vacuum arc melting technology to melt the pre-configured metal elements, and the method is simple and easy to control. x The prepared Cr2FeNiNb BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The XRD graph of the Co-free Cr2FeNiNb 0.59 eutectic entropy alloy prepared in example 1 of the present application;

[0021] Figure 2 The low-magnification SEM graph of the Co-free Cr2FeNiNb 0.59 eutectic entropy alloy prepared in example 1 of the present application;

[0022] Figure 3 The high-magnification SEM graph of the Co-free Cr2FeNiNb 0.59 eutectic entropy alloy prepared in example 1 of the present application;

[0023] Figure 4The Co-free Cr2FeNiNb 0.59 The room temperature compressive stress-strain curve of the eutectic entropy alloy. DETAILED DESCRIPTION

[0024] The specific content of the present application is further explained in detail below in combination with examples.

[0025] The Cr, Fe, Ni and Nb metal element raw materials selected in the embodiments 1-5 are Cr sheet with a purity of 99.95%, Fe particles with a purity of 99.95%, Ni particles with a purity of 99.95% and Nb block with a purity of 99.95%, and the prepared Co-free medium-entropy alloy has a chemical formula of Cr2FeNiNb x , wherein 0.2 < x < 1.

[0026] Embodiment 1

[0027] Step 1, the Cr, Fe, Ni and Nb metal element raw materials are respectively put into anhydrous ethanol and cleaned by ultrasonic wave for 15-20 min, and then dried by a hair dryer to obtain pure Cr, Fe, Ni and Nb metal elements;

[0028] Step 2, the pure Cr, Fe, Ni and Nb metal elements are weighed according to the molar ratio of 2:1:1:x, wherein x = 0.59;

[0029] Step 3, the pure Cr, Fe, Ni and Nb metal elements are sequentially placed in one of the water-cooled crucibles in the non-consumable arc melting furnace according to the order of the melting point from low to high, and the metal Ti element for removing residual oxygen in the furnace is placed in the other water-cooled crucible, then the non-consumable arc melting furnace is repeatedly vacuumed and argon is injected, so that the vacuum degree in the furnace body is 3x10 -3 Pa, the gas pressure is 0.05 Pa, the electromagnetic stirring switch is turned on, and the arc melting is started under the electromagnetic stirring, first melting for 4 min, then the alloy ingot is obtained after cooling, the alloy ingot is turned over and then re-melted by arc for 4 min, and the re-melting is repeated for 5 times, and the furnace is cooled to room temperature, to obtain the Co-free Cr2FeNiNb 0.59 eutectic medium-entropy alloy.

[0030] It can be seen from Figure 1 that the Co-free Cr2FeNiNb 0.59 eutectic medium-entropy alloy is prepared in the embodiment 1.

[0031] It can be seen from Figure 2 and Figure 3 that the Co-free Cr2FeNiNb 0.59The eutectic entropy alloy is composed of fine lamellar eutectic FCC / Laves and coarse irregular eutectic BCC / Laves, and as a whole, it is a full eutectic alloy, which gives it excellent strength and toughness.

[0032] Co-free Cr2FeNiNb 0.59 Three test samples were taken from the eutectic entropy alloy prepared in Example 1, which were sequentially used as sample 1, sample 2 and sample 3 (denoted as 1, 2 and 3 respectively) to test the mechanical properties at room temperature and draw the room temperature compression stress-strain curve. The specific mechanical property parameters are shown in Table 1. Figure 4 The room temperature compression stress-strain curve of the Co-free Cr2FeNiNb 0.59 eutectic entropy alloy prepared in Example 1 shows that the fracture strength of the eutectic entropy alloy is 2715±137 MPa, the fracture strain is 8.99±0.24%, and the alloy has good strength and toughness.

[0033] Table 1: Mechanical property parameters of the Co-free Cr2FeNiNb 059 eutectic entropy alloy prepared in Example 1

[0034]

[0035]

[0036] Example 2

[0037] Step 1, take Cr, Fe, Ni, Nb metal elements and put them into anhydrous ethanol, and clean them with ultrasonic wave for 15-20 min, and dry them with a hair dryer to obtain pure Cr, Fe, Ni and Nb metal elements;

[0038] Step 2, weigh the pure Cr, Fe, Ni and Nb metal elements according to the molar ratio of 2:1:1:x, wherein x=0.21;

[0039] Step 3, place the pure Cr, Fe, Ni and Nb metal elements in the order of low to high melting point in one of the water-cooled crucibles in the non-consumable arc melting furnace, and place the metal Ti element for removing residual oxygen in the other water-cooled crucible, then repeatedly vacuumize the non-consumable arc melting furnace and inject argon, so that the vacuum degree inside the furnace body is 4×10 -3 Pa, the gas pressure is 0.05 Pa, the electromagnetic stirring switch is turned on, and the arc melting is started under electromagnetic stirring. First melt for 5 min, then turn over the alloy ingot after cooling, and remelt it with arc for 5 min. Repeat the remelting for 5 times, and cool the furnace to room temperature to obtain the Co-free Cr2FeNiNb 0.21 eutectic entropy alloy.

[0040] Example 3

[0041] Step 1, take Cr, Fe, Ni, Nb metal element raw materials respectively into anhydrous ethanol, clean for 15-20 min by ultrasonic, dry with a hair dryer, get pure Cr, Fe, Ni, Nb metal element;

[0042] Step 2, according to the molar ratio 2:1:1:x, take pure Cr, Fe, Ni, Nb metal element, wherein x=0.99;

[0043] Step 3, place the pure Cr, Fe, Ni, Nb metal element in the order of low to high melting point in one of the water-cooled crucibles in the non-consumable arc furnace, place the metal Ti element in the other water-cooled crucible for removing residual oxygen in the furnace, then repeatedly vacuumize the non-consumable arc furnace and flush in argon, make the vacuum degree in the furnace body 5x10 -3 Pa, gas pressure 0.05 Pa, open the electromagnetic stirring switch, start arc melting under electromagnetic stirring, melt for 5 min first, get alloy ingot after cooling, turn it over and remelt for 5 min again, repeat for 5 times, cool to room temperature with the furnace, get Co-free Cr2FeNiNb 0.99 eutectic entropy alloy.

[0044] Example 4

[0045] Step 1, take Cr, Fe, Ni, Nb metal element raw materials respectively into anhydrous ethanol, clean for 15-20 min by ultrasonic, dry with a hair dryer, get pure Cr, Fe, Ni, Nb metal element;

[0046] Step 2, according to the molar ratio 2:1:1:x, take pure Cr, Fe, Ni, Nb metal element, wherein x=0.4;

[0047] Step 3, place the pure Cr, Fe, Ni, Nb metal element in the order of low to high melting point in one of the water-cooled crucibles in the non-consumable arc furnace, place the metal Ti element in the other water-cooled crucible for removing residual oxygen in the furnace, then repeatedly vacuumize the non-consumable arc furnace and flush in argon, make the vacuum degree in the furnace body 6x10 -3 Pa, gas pressure 0.05 Pa, open the electromagnetic stirring switch, start arc melting under electromagnetic stirring, melt for 4 min first, get alloy ingot after cooling, turn it over and remelt for 4 min again, repeat for 5 times, cool to room temperature with the furnace, get Co-free Cr2FeNiNb 0.4 eutectic entropy alloy.

[0048] Example 5

[0049] Step 1, take Cr, Fe, Ni, Nb metal elements respectively into anhydrous ethanol and clean them by ultrasonic for 15-20 min, and dry them by a hair dryer to obtain pure Cr, Fe, Ni, Nb metal elements;

[0050] Step 2, take pure Cr, Fe, Ni, Nb metal elements according to the molar ratio of 2:1:1:x, wherein x=0.8;

[0051] Step 3, place the pure Cr, Fe, Ni, Nb metal elements in the order of low to high melting point into one of the water-cooled crucibles in the non-consumable arc melting furnace, and place the metal Ti element in the other water-cooled crucible to remove the residual oxygen in the furnace, then repeatedly vacuumize the non-consumable arc melting furnace and inject argon, so that the vacuum degree inside the furnace body is 3x10 -3 Pa, the gas pressure is 0.05 Pa, the electromagnetic stirring switch is turned on, the arc melting is started under electromagnetic stirring, first melted for 5 min, after cooling, the alloy ingot is obtained, the alloy ingot is turned over and remelted by arc for 5 min, and the above process is repeated for 5 times, and the furnace is cooled to room temperature, to obtain a Co-free Cr2FeNiNb 0.8 eutectic entropy alloy.

Claims

1. A Co-free Cr2FeNiNb x eutectic entropy alloy characterized by, The components include Cr, Fe, Ni and Nb, and the molar ratio of Cr, Fe, Ni and Nb is 2:1:1:x, wherein 0.2 2. The Co-free type Cr2FeNiNb alloy according to claim 1 x eutectic entropy alloy characterized by, The layer sheet FCC / Laves eutectic and irregular BCC / Laves eutectic are included.

3. A Co-free type Cr2FeNiNb alloy as claimed in claim 1 or 2 x Method for producing a eutectic entropy alloy, characterized in that, The method comprises the following steps: Step 1, pure Cr, Fe, Ni and Nb metal elements are weighed according to the molar ratio of 2:1:1:x, wherein 0.2 Step 2, pure Cr, Fe, Ni, Nb metals are placed in the water-cooled crucible in the non-consumable arc furnace in order from low to high melting point, vacuum is repeatedly drawn on the non-consumable arc furnace and argon is filled, then arc is repeatedly used for smelting, and after cooling to room temperature, Co-free Cr2FeNiNb is obtained x eutectic entropy alloy.

4. The Co-free Cr2FeNiNb alloy of claim 3 x A method for producing a eutectic entropy alloy, characterized by, The step 1 further comprises the following steps: the pure Cr, Fe, Ni and Nb metal elements are respectively placed in anhydrous ethanol and cleaned by ultrasonic wave for 15-20 minutes, and then dried by a hair dryer to obtain the pure Cr, Fe, Ni and Nb metal elements.

5. The Co-free Cr2FeNiNb alloy of claim 4 x Method for producing a eutectic entropy alloy, characterized by, The pure Cr, Fe, Ni and Nb metal elements are respectively Cr sheet with a purity of 99.95%, Fe particle with a purity of 99.95%, Ni particle with a purity of 99.95% and Nb block with a purity of 99.95%.

6. The Co-free Cr2FeNiNb alloy of claim 3 x Method for producing a eutectic entropy alloy, characterized in that, The non-consumable arc melting furnace of the step 2 has at least two water-cooled crucibles, one of which is used to place the pure Cr, Fe, Ni and Nb metal elements, and the other of which is used to place the metal Ti element for removing residual oxygen in the furnace.

7. The Co-free Cr2FeNiNb alloy of claim 3 x Method for producing a eutectic entropy alloy, characterized by, Said step 2 repeatedly evacuates the non-consumable arc furnace to a vacuum degree of 3x10 -3 ~ 6x10 -3 Pa in the interior of the furnace body.

8. The Co-free Cr2FeNiNb alloy of claim 3 x A method for preparing a eutectic entropy alloy, characterized by, After the non-consumable arc melting furnace of the step 2 is repeatedly vacuumized and filled with argon, the gas pressure in the furnace body is 0.05 Pa.

9. The Co-free Cr2FeNiNb alloy of claim 3 x A method for preparing a eutectic entropy alloy, characterized by, The step 2 utilizes the process of repeated arc melting: first, the Cr, Fe, Ni and Nb metal elements in the water-cooled crucible are melted by arc for 4-5 min, and after cooling, the alloy ingot is obtained; the alloy ingot is turned over and then remelted by arc for 4-5 min, and so on for 5 times of repeated remelting; the furnace is cooled to room temperature, and the Co-free Cr2FeNiNb x Eutectic entropy alloy.

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