Refractory high-entropy composite alloy coating with excellent interface combination and preparation method of refractory high-entropy composite alloy coating

Abstract

The invention discloses a refractory high-entropy composite alloy coating with excellent interface combination and a preparation method of the refractory high-entropy composite alloy coating. According to the high-entropy composite coating, x% of refractory high-entropy alloy powder WMoTaNb and (100-x)% of 316L powder are mixed and then are subjected to a laser cladding technology, and the high-performance refractory high-entropy composite alloy coating which is excellent in coating-matrix interface combination and free of defects on a cladding layer is prepared on a to-be-cladded matrix which is 45 # steel, wherein x% is larger than 100% and larger than 30%. According to the method, thermal stress is effectively reduced, so that initiation and expansion of cracks are inhibited, the problem that an existing WMoTaNb series refractory high-entropy coating is prone to cracking is solved, and preparation of the high-entropy composite coating which is excellently combined with a matrix interface is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of metal materials, and in particular relates to a refractory high-entropy composite alloy coating with excellent interface bonding prepared by laser cladding technology and a preparation method thereof. Background Art

[0002] High-entropy alloys (HEAs) are different from traditional engineering alloys. They are a new type of metal material made by mixing multiple elements in equal or approximately equal proportions. They have high temperature resistance, high strength, high temperature oxidation resistance, excellent wear resistance and corrosion resistance, and are considered to be high-temperature resistant materials with great potential. Due to its unique alloy phase structure, organizational structure, and new design concept, it is currently a hot spot in the research of high-temperature alloy materials. At present, high-temperature materials are mainly nickel-based high-temperature alloys, which are widely used as high-temperature component materials because of their excellent high-temperature properties such as creep resistance, high temperature resistance and corrosion resistance. However, the effective use temperature of nickel-based high-temperature alloys is up to about 1150℃. Even if refractory alloying elements such as W are added, the increase in service temperature is limited. In 2010, Professor Senkov and his colleagues used the concept of high entropy to prepare for the first time a series of refractory high entropy alloys (RHEAs). By mixing a variety of high melting point elements in equal molar proportions, such as Hf, Nb, Ta, Mo, W and other refractory elements, the alloys have excellent high temperature strength, corrosion resistance, wear resistance and high temperature oxidation resistance, and have excellent application prospects under ultra-high temperatures.

[0003] At present, the existing preparation forms of refractory high entropy alloys are mainly divided into block and coating / film. However, due to the limitations of casting cavity and mold, it is difficult to prepare large-sized and complex-structured block components. In addition, the high cost of using high entropy alloys as block materials is high, which to a certain extent limits the industrial and commercial application of refractory high entropy alloys. With the development of surface engineering technology, the use of laser cladding technology to prepare refractory high entropy alloy coatings provides a feasible solution to this problem. The preparation of refractory high entropy alloy coatings on the surface of component materials enables the base material to have the properties of refractory high entropy alloys, and greatly reduces the manufacturing cost, which is conducive to the realization of engineering and commercial applications. In the laser cladding process, due to the large melting point difference between refractory elements such as W, Mo, Ta, and Nb, the cladding coating is easily affected by the laser energy distribution, temperature gradient, and solidification rate, resulting in large residual stress, which in turn causes defects in the cladding layer and even cracks, making it difficult to achieve large-scale industrial applications. Summary of the invention

[0004] In view of the problem that cracks are easily generated during the preparation of the above-mentioned cladding coating, the present invention preferably selects 316L alloy powder according to the characteristics of the substrate material to be clad, mixes WMoTaNb refractory high entropy alloy powder with 316L alloy powder in a certain mass percentage, and then regulates the elements, component content, microstructure of the alloy coating, and alleviates thermal stress. Not only does it achieve excellent bonding between the coating and the substrate interface, effectively inhibit the initiation and propagation of cracks, but also compared with the substrate, its surface hardness performance is improved, thereby meeting people's needs for industrial application of materials.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A laser cladding refractory high entropy composite alloy coating with excellent interface bonding and a preparation method thereof, wherein the high entropy composite coating is prepared by mixing x% of refractory high entropy alloy powder WMoTaNb and (100-x)% of 316L powder by laser cladding technology, 100%>x%>30%, and specifically comprises the following steps:

[0007] Step 1, mixing refractory high entropy alloy powder WMoTaNb and 316L alloy powder according to mass percentage, and drying them under the protection of inert gas to remove trace moisture in the powder, improve the fluidity of the powder, and effectively avoid increasing the oxygen content in the powder;

[0008] Step 2: Coaxial powder feeding is used to coat the powder to be clad on the surface of the substrate to be clad, and laser cladding is performed using a laser according to the set laser cladding parameters and scanning method.

[0009] Preferably, the substrate to be clad is 45# steel.

[0010] Preferably, 70% ≥ x% ≥ 30%.

[0011] Preferably, in step 1), the purity (wt.%) of each component in the refractory high entropy alloy powder WMoTaNb and 316L powder is greater than 99.9%, and the particle size is 15-50 μm.

[0012] Preferably, in step 1), the drying treatment temperature is 90-120° C. and the time is 6-8 hours.

[0013] Preferably, in step 2), the substrate to be clad is cleaned with alcohol or acetone to remove surface stains and impurities.

[0014] Preferably, in step 2), during laser cladding, the laser power is 1000-2000W and the scanning rate is 8-50mm / s; the scanning mode is single-layer strip reciprocating scanning, the single-track width is 1-3mm, the single-track height is 0.5-1.5mm, and the single-layer height is 0.5-1.5mm; the powder feeding gas flow rate is 8-10L / min, and the gas pressure is 0.5-0.8Mpa; the protective gas is argon, and the argon flow rate is 8-20L / min.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) Due to the high strength and hardness of refractory high entropy alloys, cracks are prone to occur during the preparation of cladding coatings. 316L alloy powder is preferred. WMoTaNb refractory high entropy alloy powder is mixed with the preferred alloy powder in a certain mass percentage and then clad. This effectively reduces thermal stress, thereby inhibiting the initiation and propagation of cracks, overcoming the problem of easy cracking of existing WMoTaNb refractory high entropy coatings, and realizing the preparation of high-entropy composite coatings with excellent interface bonding with the substrate.

[0017] (2) The present invention adjusts the microstructure of the refractory high entropy composite alloy coating by mixing WMoTaNb refractory high entropy alloy powder with a preferred transitional alloy powder in a certain mass percentage, thereby increasing the microhardness and further improving the impact resistance and wear resistance.

[0018] (3) The operation method of the present invention is simple and flexible, and the powder mixture selection and proportioning can be carried out according to the cladding substrate material, and is suitable for the preparation of refractory high-entropy composite alloy coatings of various systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 These are actual pictures of the laser cladding refractory high entropy composite alloy coating samples described in Examples 1-4, wherein (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is Example 4.

[0020] Figure 2 These are SEM images of the bonding area morphology of the laser cladding refractory high entropy composite alloy coating samples described in Examples 1-4, wherein (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is Example 4.

[0021] Figure 3 These are SEM images of the microstructure and organization of the laser-clad refractory high-entropy composite alloy coating samples described in Examples 1-4, wherein (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is Example 4. DETAILED DESCRIPTION

[0022] The present invention is described in detail below through the accompanying drawings and specific implementation methods so that those skilled in the art can better understand and implement the present invention. The following examples are not intended to limit the present invention.

[0023] Example 1

[0024] A laser cladding refractory high entropy composite alloy coating, based on the substrate to be clad being 45# steel, preferably 316L stainless steel alloy powder, the composition of the coating is WMoTaNb (50%) / 316L (50%), and the composition percentage is mass percentage. It includes the following steps:

[0025] Step 1: Select WMoTaNb refractory high entropy alloy powder (commercially available from Beijing Yijin New Materials Technology Co., Ltd.) and 316L stainless steel powder (commercially available from Beijing Yijin New Materials Technology Co., Ltd.) as the powder to be clad, with a purity (wt.%) greater than 99.9% and a particle size range of 35 to 45 μm, and mix them at a mass percentage of 50%. Dry the powder to be clad in an inert gas protection drying oven, and introduce argon as a protective gas during the drying process. The powder baking temperature is 120°C and the insulation time is 8 hours. After the insulation is completed, argon is continuously introduced into the drying oven for cooling, and the powder is taken out after cooling to a temperature of 25°C. Dry the powder to be clad in an inert gas protection drying oven.

[0026] Step 2: Select 45# steel as the substrate to be clad and clean it with ethanol to remove surface impurities.

[0027] Step 3: Put the cladding powder into the coaxial powder feeder of the cladding equipment, set the powder feeding gas flow rate to 8L / min, the gas pressure to 0.5Mpa, and spray it on the surface of the 45# steel to be clad through the powder feeder. At the same time, use the Laserline laser to perform laser cladding on the surface of the material to be clad. The laser cladding parameters are: laser power of 1900W, scanning rate of 10mm / s; shielding gas flow rate of 20L / min, shielding gas and powder feeding gas are both argon, scanning mode is single-layer strip reciprocating scanning, single-channel width is 2.5mm, single-channel height is 0.7mm, and single-layer height is 1mm.

[0028] The prepared samples are as follows Figure 1 As shown in (a), there is no crack on the sample surface and the cladding quality is good. The microscopic morphology of the bonding area between the sample coating and the substrate is shown in Figure 2 As shown in (a), the bonding area is dense, the bonding is excellent, and there is no crack in the whole. Figure 3 As shown in (a), the phase structure is distributed in a network and there are no cracks as a whole.

[0029] Example 2

[0030] A laser cladding refractory high entropy composite alloy coating, based on the substrate to be clad being 45# steel, preferably 316L stainless steel alloy powder, the composition of the coating is WMoTaNb (30%) / 316L (70%), and the composition percentage is mass percentage. It includes the following steps:

[0031] Step 1: Select WMoTaNb refractory high entropy alloy powder (commercially available from Beijing Yijin New Material Technology Co., Ltd.) and 316L stainless steel powder (commercially available from Beijing Yijin New Material Technology Co., Ltd.) as the powder to be clad, with a purity (wt.%) greater than 99.9% and a particle size range of 35 to 45 μm, and mix them in the mass percentage of WMoTaNb (30%) / 316L (70%). Dry the powder to be clad in an inert gas protection drying oven, and introduce argon as a protective gas during the drying process. The powder baking temperature is 120°C and the insulation time is 8 hours. After the insulation is completed, argon is continuously introduced into the drying oven for cooling, and the powder is taken out after cooling to a temperature of 25°C. Dry the powder to be clad in an inert gas protection drying oven.

[0032] Step 2: Select 45# steel as the substrate to be clad and clean it with ethanol to remove surface impurities.

[0033] Step 3: Put the cladding powder into the coaxial powder feeder of the cladding equipment, set the powder feeding gas flow rate to 8L / min, the gas pressure to 0.5Mpa, and spray it on the surface of the 45# steel to be clad through the powder feeder. At the same time, use the Laserline laser to perform laser cladding on the surface of the material to be clad. The laser cladding parameters are: laser power of 1900W, scanning rate of 10mm / s; shielding gas flow rate of 20L / min, shielding gas and powder feeding gas are both argon, scanning mode is single-layer strip reciprocating scanning, single-channel width is 2.5mm, single-channel height is 0.7mm, and single-layer height is 1mm.

[0034] The prepared samples are as follows Figure 1 As shown in (b), there is no crack on the sample surface and the cladding quality is good. The microscopic morphology of the bonding area between the sample coating and the substrate is as follows: Figure 2 As shown in (b), the bonding area is dense, the bonding is excellent, and there is no crack in the whole. Figure 3 As shown in (b), the phase structure is distributed in a dense network with no cracks as a whole.

[0035] Example 3

[0036] A laser cladding refractory high entropy composite alloy coating, based on the substrate to be clad being 45# steel, preferably 316L stainless steel alloy powder, the composition of the coating is WMoTaNb (70%) / 316L (30%), and the composition percentage is mass percentage. It includes the following steps:

[0037] Step 1: Select WMoTaNb refractory high entropy alloy powder (commercially available from Beijing Yijin New Material Technology Co., Ltd.) and 316L stainless steel powder (commercially available from Beijing Yijin New Material Technology Co., Ltd.) as the powder to be clad, with a purity (wt.%) greater than 99.9% and a particle size range of 35 to 45 μm, and mix them in the mass percentage of WMoTaNb (70%) / 316L (30%). Dry the powder to be clad in an inert gas protection drying oven, and introduce argon as a protective gas during the drying process. The powder baking temperature is 120°C and the insulation time is 8 hours. After the insulation is completed, argon is continuously introduced into the drying oven for cooling, and the powder is taken out after cooling to a temperature of 25°C. Dry the powder to be clad in an inert gas protection drying oven.

[0038] Step 2: Select 45# steel as the substrate to be clad and clean it with ethanol to remove surface impurities.

[0039] Step 3: Put the cladding powder into the coaxial powder feeder of the cladding equipment, set the powder feeding gas flow rate to 8L / min, the gas pressure to 0.5Mpa, and spray it on the surface of the 45# steel to be clad through the powder feeder. At the same time, use the Laserline laser to perform laser cladding on the surface of the material to be clad. The laser cladding parameters are: laser power of 1900W, scanning rate of 10mm / s; shielding gas flow rate of 20L / min, shielding gas and powder feeding gas are both argon, scanning mode is single-layer strip reciprocating scanning, single-channel width is 2.5mm, single-channel height is 0.7mm, and single-layer height is 1mm.

[0040] The prepared samples are as follows Figure 1 As shown in (c), there is no crack on the sample surface and the cladding quality is good. The microscopic morphology of the bonding area between the sample coating and the substrate is as follows: Figure 2 As shown in (c), the bonding area is dense, the bonding is excellent, and there is no crack in the whole. Figure 3 As shown in (c), the phase structure is distributed in a coarse dendrite structure with no cracks as a whole.

[0041] Example 4

[0042] A laser cladding refractory high entropy composite alloy coating, the cladding substrate is 45# steel, and the composition of the coating to be clad is WMoTaN b. It includes the following steps:

[0043] Step 1: Select WMoTaNb refractory high entropy alloy powder (commercially available from Beijing Yijin New Materials Technology Co., Ltd.) as the powder to be clad, with a purity (wt.%) greater than 99.9% and a particle size range of 35 to 45 μm. Dry the powder to be clad in an inert gas protection drying oven. During the drying process, argon gas is introduced as a protective gas. The powder baking temperature is 120°C and the insulation time is 8 hours. After the insulation is completed, argon gas is continuously introduced into the drying oven for cooling. Take it out after cooling to a temperature of 25°C. And dry the powder to be clad in an inert gas protection drying oven.

[0044] Step 2: Select 45# steel as the substrate to be clad and clean it with ethanol to remove surface impurities.

[0045] Step 3: Put the cladding powder into the coaxial powder feeder of the cladding equipment, set the powder feeding gas flow rate to 8L / min, the gas pressure to 0.5Mpa, and spray it on the surface of the 45# steel to be clad through the powder feeder. At the same time, use the Laserline laser to perform laser cladding on the surface of the material to be clad. The laser cladding parameters are: laser power of 1900W, scanning rate of 10mm / s; shielding gas flow rate of 20L / min, shielding gas and powder feeding gas are both argon, scanning mode is single-layer strip reciprocating scanning, single-channel width is 2.5mm, single-channel height is 0.7mm, and single-layer height is 1mm.

[0046] The prepared samples are as follows Figure 1 As shown in (d) in the figure, large cracks appear on the sample surface and part of the cladding layer falls off. The microscopic morphology of the bonding area between the sample coating and the substrate is shown in Figure 2 As shown in (d) in the figure, the bonding area is uneven and there is a large crack between the substrate and the coating. Figure 3 As shown in (d), the phase structure is distributed in a dendritic structure, and there are unmelted alloy powders and large cracks.

[0047] In summary, the present invention adjusts the mixed mass percentage of WMoTaNb refractory high entropy alloy powder and 316L alloy powder and adopts laser cladding technology to prepare a high-performance refractory high entropy composite alloy coating with excellent coating-substrate interface bonding and defect-free cladding layer.

Claims

1. A method for preparing a refractory high entropy composite alloy coating with excellent interface bonding, characterized in that: In terms of mass percentage, the high entropy composite coating is prepared by mixing x% of refractory high entropy alloy powder WMoTaNb and (100-x)% of 316L powder and then using laser cladding technology, 100%>x%>30%, and specifically includes the following steps: Step 1, mixing refractory high entropy alloy powder WMoTaNb and 316L alloy powder according to mass percentage, and drying them under the protection of inert gas to remove trace moisture in the powder, improve the fluidity of the powder, and effectively avoid increasing the oxygen content in the powder; Step 2: Coaxial powder feeding is used to coat the powder to be clad on the surface of the substrate to be clad, and laser cladding is performed using a laser according to the set laser cladding parameters and scanning method.

2. The method according to claim 1, characterized in that The substrate to be clad is 45# steel.

3. The method according to claim 1, characterized in that 70%≥x%≥30%。 4. The method according to claim 1, characterized in that In step 1), the purity (wt.%) of each component in the refractory high entropy alloy powder WMoTaNb and 316L powder is greater than 99.9%, and the particle size is 15-50 μm.

5. The method according to claim 1, characterized in that In step 1), the drying temperature is 90-120° C. and the time is 6-8 hours.

6. The method according to claim 1, characterized in that In step 2), the substrate to be clad is cleaned with alcohol or acetone to remove surface stains and impurities.

7. The method according to claim 1, characterized in that In step 2), during laser cladding, the laser power is 1000-2000W and the scanning rate is 8-50mm / s; the scanning mode is single-layer strip reciprocating scanning, the single-channel width is 1-3mm, the single-channel height is 0.5-1.5mm, and the single-layer height is 0.5-1.5mm; the powder feeding gas flow rate is 8-10L / min, and the gas pressure is 0.5-0.8Mpa; the protective gas is argon, and the argon flow rate is 8-20L / min.

8. A refractory high entropy composite alloy coating prepared by the method according to any one of claims 1 to 7.

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