Laser cladding dual-phase high-entropy alloy coating and preparation method thereof

Abstract

The application discloses a laser cladding dual-phase high-entropy alloy coating and a preparation method thereof, and belongs to the technical field of laser surface modification. The laser cladding dual-phase high-entropy alloy coating comprises the following raw materials in percentage of atoms: 9-16% of Al, 11-17% of Cr, 11-18% of Fe, 13-20% of Ti, 10-15% of V and 28-33% of Ni. The laser cladding dual-phase high-entropy alloy coating has good high-temperature oxidation resistance and wear resistance, can match the thermal physical parameters of a TC4 titanium alloy base material, has no obvious defects and forms metallurgical bonding with the base material, can prolong the service life of the TC4 titanium alloy, widens the application scene of the TC4 titanium alloy under extreme working conditions, and greatly saves the development resources of the TC4 titanium alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser surface modification, in particular to a laser cladding dual-phase high-entropy alloy coating and a preparation method thereof. BACKGROUND

[0002] High-entropy alloy is a new type of metal material with unique design strategy, the alloy composition is mixed by five or more elements in equal molar ratio or close to equal molar ratio, and the concentration of each element is 5% to 35%, under the action of high mixing entropy, the system tends to form a single-phase solid solution, this method breaks through the design concept of traditional alloy, and expands the composition design from the corner to the center of the phase diagram, thereby obtaining excellent comprehensive performance.

[0003] Since the concept of high-entropy alloy was proposed, domestic and foreign researchers have conducted a large number of systematic researches. Initially, the phase structure was stabilized by maximizing the entropy value to obtain excellent and stable performance, but this method has certain limitations (a simple microstructure is obtained, but at the same time, the upper limit of its performance is also limited), therefore, the strict restriction on the composition is relaxed, and the alloy elements or composition are adjusted to realize a multi-phase structure, so as to further improve the strength and toughness of the alloy and reduce the brittleness of the alloy, but the result is not very ideal, therefore, it is urgent to find a method to break through the above limitations, so as to obtain an alloy coating material with more excellent performance. SUMMARY

[0004] The purpose of the present application is to provide a laser cladding dual-phase high-entropy alloy coating and a preparation method thereof, so as to solve the problems existing in the prior art. The laser cladding dual-phase high-entropy alloy coating has low brittleness, reduces the crack sensitivity of the laser cladding coating, has good quality and excellent comprehensive performance.

[0005] In order to achieve the above purpose, the present application provides the following solutions.

[0006] One of the technical solutions of the present application: a laser cladding dual-phase high-entropy alloy coating, which comprises the following raw materials in atomic percentage: Al 9-16%, Cr 11-17%, Fe 11-18%, Ti 13-20%, V 10-15%, and Ni 28-33%.

[0007] The second technical solution of the present application: a preparation method of the above laser cladding dual-phase high-entropy alloy coating, comprising the following steps:

[0008] Mixing and ball-milling the raw materials to obtain alloy powder, prepositioning the alloy powder on the surface of the substrate, drying, and then performing laser cladding to obtain the laser cladding dual-phase high-entropy alloy coating.

[0009] Furthermore, the ball-to-material ratio of the ball mill is 5:1, the rotation speed is 100-140 rpm, and the time is 6-10 hours.

[0010] Furthermore, the ball milling method is to alternately perform forward rotation and reverse rotation with a pause of 10 to 20 minutes in between; the forward rotation time is 20 to 30 minutes, and the reverse rotation time is 20 to 30 minutes.

[0011] Furthermore, the particle size of the raw material is 15 to 53 μm; and the preset thickness of the alloy powder is 0.7 to 1.3 mm.

[0012] Furthermore, the drying temperature is 60-80° C. and the drying time is 6-8 hours.

[0013] Furthermore, the ratio of the surface area of ​​the substrate to the preset area of ​​the alloy powder is 14 mm 2 :4mm 2 ; The alloy powder is pre-placed in the middle of the substrate.

[0014] Furthermore, the conditions for the laser cladding include: an output power of 600 to 850 W, a spot diameter of 3 to 4 mm, a laser scanning speed of 200 to 350 mm / min, and an inert atmosphere.

[0015] Furthermore, the substrate includes a titanium alloy substrate (such as a TC4 titanium alloy substrate).

[0016] The third technical solution of the present invention: an application of the above-mentioned laser cladding dual-phase high-entropy alloy coating in the aerospace field.

[0017] The present invention discloses the following technical effects:

[0018] (1) The laser-clad dual-phase high-entropy alloy coating of the present invention has good resistance to high-temperature oxidation and wear resistance, and can match the thermophysical parameters of the TC4 titanium alloy substrate. The cladding layer has no obvious defects and forms a metallurgical bond with the substrate, which can extend the service life of the TC4 titanium alloy, broaden its application scenarios in extreme working conditions, and greatly save the development resources of the TC4 titanium alloy.

[0019] (2) The present invention introduces the Ni element into the laser cladding dual-phase high-entropy alloy coating, utilizes Al / Ni to form an ordered B2 phase with the same BCC structure, and regulates the microstructure of the coating, thereby improving the comprehensive performance of the coating (less brittleness, good wear resistance, and a wear rate of only 12.8% of that of the TC4 titanium alloy substrate).

[0020] Furthermore, the laser cladding dual-phase high entropy alloy coating of the present invention has excellent oxidation resistance in air at 800° C., and compared with the TC4 titanium alloy substrate, the oxidation rate of the coating is reduced by 55%.

[0021] (3) The present invention lays the mixed alloy powder on the surface of the TC4 titanium alloy substrate by a pre-setting method, and irradiates the powder with a high-energy laser beam to obtain a coating that is metallurgically bonded to the substrate, has good forming quality and good comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a cross-sectional morphology of the laser-clad dual-phase high-entropy alloy coating prepared in Example 1 of the present invention;

[0024] Figure 2 XRD patterns of the laser cladding dual-phase high-entropy alloy coating prepared in Example 1 of the present invention, the high-entropy alloy coating prepared in Comparative Example 1, and the high-entropy alloy coating prepared in Comparative Examples 1-2;

[0025] Figure 3 The SEM and element distribution diagram of the laser-clad dual-phase high-entropy alloy coating prepared in Example 1 of the present invention;

[0026] Figure 4 Wear rate graphs of the TC4 titanium alloy substrate (Ti6Al4V) used in the present invention, the laser-clad dual-phase high-entropy alloy coating prepared in Example 1, the high-entropy alloy coating prepared in Comparative Example 1, and the high-entropy alloy coatings prepared in Comparative Examples 2-3;

[0027] Figure 5 These are the oxidation weight gain curves of the TC4 titanium alloy substrate (Ti6Al4V) used in the present invention, the laser cladding dual-phase high-entropy alloy coating prepared in Example 1, the high-entropy alloy coating prepared in Comparative Example 1, and the high-entropy alloy coating prepared in Comparative Examples 2 to 3. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] Example 1

[0034] A method for preparing a laser cladding dual-phase high entropy alloy coating:

[0035] (1) The laser cladding dual-phase high entropy alloy coating is composed of the following raw materials in atomic percentage: Al 14%, Cr 14%, Fe 14%, Ti 14%, V 14%, and Ni 30%.

[0036] (2) Al powder, Cr powder, Fe powder, Ti powder, V powder and Ni powder were weighed out according to atomic percentage using an electronic balance with an accuracy of ±0.1 mg (all powders were commercial spherical powders with a particle size of 15 to 53 μm).

[0037] (3) The raw material powders were mixed according to the proportions and placed in a ball mill. The ball-to-material ratio was controlled to be 5:1, the grinding balls were stainless steel balls with a diameter of 3 mm, and the rotation speed was 120 rpm. Ball milling was performed alternately in forward and reverse rotations. The forward rotation time was 20 min, the reverse rotation time was 20 min, and a pause of 15 min in the middle was used as one ball milling cycle. The mixing was continued for 10 h to obtain alloy powder.

[0038] (4) The TC4 titanium alloy was cut into 40 mm × 14 mm × 4 mm plates by wire cutting, and then the oxides and oil stains on the surface of the TC4 titanium alloy were removed by coarse grinding with 400-mesh metallographic sandpaper. The alloy was placed in alcohol ultrasonic treatment for 10 minutes and then dried to obtain the TC4 titanium alloy substrate.

[0039] (5) The alloy powder is pre-placed on the surface of the TC4 titanium alloy substrate. The pre-placed powder size is 40 mm × 4 mm × 1 mm and is pre-placed in the middle of the substrate surface to obtain a prefabricated sample.

[0040] (6) The prefabricated sample was placed in a vacuum dryer and dried at 80°C for 6 h to obtain a dried sample.

[0041] (7) Place the dried sample in a fiber laser irradiation device and release argon for 5 minutes. - 1 Argon was continuously supplied at a speed of 100 nm, and the laser output power was controlled to be 800 W, the spot diameter was 3 mm, and the laser scanning speed was 300 mm / min to perform fiber laser irradiation on the pre-deposited layer. After irradiation, the argon supply was maintained for 5 minutes until the sample was completely cooled, and a laser cladding dual-phase high entropy alloy coating (named Al based on the atomic weight ratio) was obtained. 14 Cr 14 Fe 14 Ti 14 V 14 Ni 30 ) of TC4 titanium alloy.

[0042] Comparative Example 1

[0043] The same as Example 1, except that the alloy coating (AlCrFeTiV) is composed of the following raw materials, by mass percentage: Al 12wt.%, Cr 22wt.%, Fe 24wt.%, Ti 21wt.%, V 21wt.% (atomic percentage is 1:1:1:1:1).

[0044] Comparative Example 2

[0045] The same as Example 1, except that the laser cladding dual-phase high entropy alloy coating is composed of the following raw materials in atomic percentage: Al 16%, Cr 16%, Fe 16%, Ti 16%, V 16%, Ni 20%.

[0046] Comparative Example 3

[0047] The same as Example 1, except that the laser cladding dual-phase high entropy alloy coating is composed of the following raw materials in atomic percentage: Al 18%, Cr 18%, Fe 18%, Ti 18%, V 18%, Ni 10%.

[0048] Effect Example 1

[0049] The cross-sectional morphology of the laser cladding dual-phase high entropy alloy coating prepared in Example 1 is shown in FIG. Figure 1 .

[0050] from Figure 1 As can be seen from the figure, there are no obvious cracks in the coating, and it forms a metallurgical bond with the titanium alloy substrate. In addition, its bond line shows that the dilution rate of the substrate is not high, which can effectively guarantee the comprehensive performance of the coating.

[0051] Laser cladding dual-phase high entropy alloy coating (Ni 30 ), the high entropy alloy coating (AlCrFeTiV) prepared in Comparative Example 1, the high entropy alloy coating (Ni 20 ), the high entropy alloy coating prepared in Comparative Example 3 (Ni 10 )’s XRD pattern is shown in Figure 2 .

[0052] from Figure 2 It can be seen that with the introduction of Ni element, Laves' diffraction peak appears in the coating. When the atomic ratio of Ni element is 30%, a small diffraction peak appears at about 30 degrees, which is judged to be B2 ordered phase.

[0053] Effect Example 2

[0054] The SEM and element distribution of the laser cladding dual-phase high entropy alloy coating prepared in Example 1 are shown in Figure 3 .

[0055] from Figure 3 It can be seen from the figure that there are two distinct contrasting morphologies in the coating. The EDS surface scanning results show that the B2 phase is mainly enriched in Al and Ni.

[0056] Effect Example 3

[0057] The wear resistance of the coating was evaluated using a multifunctional wear tester (UMT-2). Si3N4 ceramic balls with a diameter of 3 mm were selected as the friction pair, and the wear test was carried out using the reciprocating wear method. Figure 4 Ti6Al4V in), the coating prepared in Example 1 ( Figure 4 Ni30 ), the coating prepared in Comparative Example 1 ( Figure 4 AlCrFeTiV in)), the coating prepared in Comparative Example 2 ( Figure 4 Ni 20 ) or the coating prepared in Comparative Example 3 ( Figure 4 Ni 10 ) Wear tests were conducted under a load of 20 N, with a wear scar length of 2 mm, an oscillation frequency of 1 Hz, and a wear duration of 30 min. The wear rate results were obtained from the corresponding wear volume, applied load, and total sliding distance. Figure 4 .

[0058] from Figure 4 It can be seen that the wear rate of TC4 titanium alloy substrate is 3.45×10 -4 mm 3 ·N -1 ·m -1 The wear rate of the AlCrFeTiV high entropy alloy coating is 2.89×10 -4 mm 3 ·N -1 ·m -1 With the introduction of Ni element, the coating wear rate decreased significantly. The wear rate of the laser cladding dual-phase high entropy alloy coating prepared in Example 1 was only 0.44×10 - 4 mm 3 ·N -1 ·m -1 , greatly improving the wear resistance of the coating.

[0059] Effect Example 4

[0060] The TC4 titanium alloy substrate (ie Ti6Al4V), the laser cladding dual-phase high entropy alloy coating (ie Ni 30 ), the high entropy alloy coating prepared in Comparative Example 1 (i.e., AlCrFeTiV), the high entropy alloy coating prepared in Comparative Example 2 (i.e., Ni 20 ), the high entropy alloy coating prepared in Comparative Example 3 (i.e. Ni 10 ) were placed in a box furnace and oxidized at 800 ° C in air for 0.5, 5, 15, 30 and 50 h. The samples were then cooled to room temperature and the weight differences of the samples were recorded using an electronic scale with an accuracy of ± 0.1 mg. The results are shown in Figure 5 .

[0061] from Figure 5As can be seen from the results, the laser-clad dual-phase high-entropy alloy coating prepared in Example 1 of the present invention significantly reduces oxidation weight gain at 800°C in air, with its oxidation rate being only 55% of that of the TC4 titanium alloy substrate. Furthermore, its high-temperature oxidation resistance is optimal when the atomic ratio of Ni is 30%.

[0062] Research revealed that the high-entropy alloy coating prepared in Comparative Example 1, a single-phase BCC high-entropy alloy coating, exhibited significantly increased cracking, was brittle, and exhibited small particle loss during grinding and polishing. Furthermore, its high-temperature oxidation resistance and wear performance were significantly reduced. The introduction of Ni in Example 1 promoted the precipitation of an ordered Al / Ni B2 phase with the same BCC structure, effectively regulating the coating's build quality and further improving its overall performance.

[0063] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A laser cladding dual-phase high entropy alloy coating, characterized in that: Calculated in atomic percentage, the following raw materials are included: Al is 9-16%, Cr is 11-17%, Fe is 11-18%, Ti is 13-20%, V is 10-15%, and Ni is 28-33%.

2. A method for preparing a laser cladding dual-phase high entropy alloy coating according to claim 1, characterized in that: The following steps are involved: The raw materials are mixed and ball-milled to obtain alloy powder, the alloy powder is pre-placed on the surface of the substrate, and laser cladding is performed after drying to obtain the laser cladding dual-phase high entropy alloy coating.

3. The preparation method according to claim 2, characterized in that The ball-to-material ratio of the ball mill is 5:1, the rotation speed is 100-140 rpm, and the time is 6-10 hours.

4. The preparation method according to claim 3, characterized in that The ball milling method is to alternately perform forward rotation and reverse rotation with a pause of 10 to 20 minutes; the forward rotation time is 20 to 30 minutes, and the reverse rotation time is 20 to 30 minutes.

5. The preparation method according to claim 2, characterized in that The particle size of the raw material is 15 to 53 μm; the preset thickness of the alloy powder is 0.7 to 1.3 mm.

6. The preparation method according to claim 2, characterized in that The laser cladding conditions include: output power of 600-850W, spot diameter of 3-4mm, laser scanning speed of 200-350mm / min, and inert atmosphere.

7. The preparation method according to claim 2, characterized in that The substrate includes a titanium alloy substrate.

8. Application of the laser cladding dual-phase high entropy alloy coating according to claim 1 in the field of aerospace.

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