阅读说明：本技术 一种高熵合金粉末及激光熔覆层制备方法和应用 (High-entropy alloy powder and preparation method and application of laser cladding layer ) 是由 胡绳荪 崔妍 申俊琦 于 2018-08-06 设计创作，主要内容包括：本发明公开一种高熵合金粉末及激光熔覆层制备方法和应用,由Fe、Co、Cr、Mn、Ni和Al元素粉末等摩尔比组成,利用合金粉末应用到激光熔覆焊接中,将高熵合金粉末和乙醇混合后,均匀涂覆在基体材料表面,干燥后通过激光熔覆即可获得熔覆层。在进行激光熔覆时,选用基体材料为H13钢,激光功率为1300～1600KW,光斑直径为2～4mm,扫描速度5～7mm/s,离焦量为10mm,保护气体流量为20～25L/min。由于激光熔覆高熵合金涂层的混乱度较大,在高温时变得更大,高的混合熵效应显著降低了元素间的扩散和重新分配速率,从而涂层中的相结构稳定,高温硬度基本保持不变,具有良好的抗高温软化性。(The invention discloses a high-entropy alloy powder and a preparation method and application of a laser cladding layer. When laser cladding is carried out, H13 steel is selected as a base material, the laser power is 1300-1600 KW, the diameter of a light spot is 2-4 mm, the scanning speed is 5-7 mm/s, the defocusing amount is 10mm, and the flow of protective gas is 20-25L/min. The laser cladding high-entropy alloy coating has larger chaos and becomes larger at high temperature, and the high mixed entropy effect obviously reduces the diffusion and redistribution rate among elements, so that the phase structure in the coating is stable, the high-temperature hardness is basically kept unchanged, and the high-temperature softening resistance is good.)

1. The high-entropy alloy powder is characterized by consisting of Fe, Co, Cr, Mn, Ni and Al element powder, namely the alloy powder composition is represented as FeCoCrNiMnAl, and the Fe, Co, Cr, Mn, Ni and Al are in equal molar ratio, namely the mole numbers of the six metal elements are consistent.

2. A high entropy alloy powder according to claim 1, wherein each component is selected to be a powder having a purity of 99% or more and a particle size of 200 to 300 mesh.

3. A method for producing a high-entropy alloy powder as claimed in claim 1 or 2, wherein the compounding ratio is calculated in terms of the molar ratio of each element, and the respective components are mixed thoroughly after the masses thereof are accurately weighed to be uniform.

4. A method for preparing high-entropy alloy powder according to claim 3, wherein the powders of the elements are weighed by an electronic scale and ground in a mortar for uniform mixing, for example, the grinding time is 0.5-1 hour.

5. The method for carrying out laser cladding welding by using the high-entropy alloy powder as claimed in claim 1 or 2, is characterized in that the high-entropy alloy powder and ethanol are mixed and then uniformly coated on the surface of a base material, a cladding layer can be obtained by laser cladding after drying, the base material is H13 steel when laser cladding is carried out, and the process parameters are as follows: the laser power is 1300-1600 KW, the diameter of a light spot is 2.0-4.0 mm, the scanning speed is 5-7 mm/s, the defocusing amount is 6-10 mm, the protective gas is argon, nitrogen or helium, and the gas flow is 20-25L/min.

6. The method of performing laser cladding welding according to claim 5, wherein the process parameters are: the laser power is 1400-1500 KW, the diameter of a light spot is 2.0-4.0 mm, the scanning speed is 6-7 mm/s, the defocusing amount is 8-10 mm, the protective gas is argon, nitrogen or helium, and the gas flow is 20-25L/min.

7. The laser cladding welding method according to claim 5 or 6, wherein the ethanol is analytically pure absolute ethanol, and the mixture of the six-element high-entropy alloy powder and the ethanol comprises 92-95% of alloy powder and 5-8% of ethanol by mass percent.

8. The method for laser cladding welding according to claim 5, wherein the high entropy alloy powder is mixed with ethanol to form paste or paste, so as to be coated on the surface of the base material, and a prefabricated layer is formed on the surface of the base material after coating, wherein the thickness of the prefabricated layer is 0.8-1.2 mm.

9. Use of a high entropy alloy powder of claim 1 or 2 to improve hardness and high temperature oxidation resistance of H13 steel.

10. Use according to claim 10, characterised in that the hardness is up to 650-670 HV and the oxidation weight gain at 700 ℃ is up to 3-3.2 x 10^-3mg/mm²。

Technical Field

The invention relates to the field of laser surface modification, in particular to the field of preparation of high-entropy alloy powder for laser cladding and a cladding layer.

Background

At present, the wide definition of the high-entropy alloy refers to an alloy consisting of 5 to 13 main elements, and the content of each element is between 5 and 30 percent. The multicomponent high-entropy alloy has become a new research hotspot in the field of metal materials because of the unique phase structure, the brand-new design concept and the excellent alloy performance, and is called three major breakthroughs in the field of alloying theories in recent years together with rubber metal and bulk metallic glass.

The high-entropy alloy has high diffusion activation energy for forming a disordered solid solution among different atoms, can seriously obstruct a diffusion process, and can still keep the structural stability under the heating condition. The high-temperature performance material in the field of materials at present has larger demand space, and the high-entropy alloy is a potential powerful choice by virtue of the advantage of thermodynamic stability.

At present, the research on high-entropy alloy mainly focuses on vacuum arc melting and casting block materials, which causes the preparation size to be greatly limited; and the metals used for preparation are expensive, so that the cost for producing large parts is too high. The preparation of the high-entropy alloy coating can not only avoid the defects, but also obtain excellent service performance. The laser cladding has high heating and cooling rates, small heat influence on a matrix, fine and uniform distribution of cladding layer grains in the matrix, metallurgical bonding between the coating and the matrix, high bonding strength and the maximum coating thickness of several millimeters.

H13(4Cr5MoSiV1) is widely used hot-work die steel, has higher hot strength and hardness, high wear resistance and toughness and better thermal fatigue resistance, and is widely applied to manufacturing various forging dies, hot extrusion dies and die-casting dies of magnesium, aluminum and alloys thereof. The H13 die casting die bears physical and chemical actions such as abrasion, thermal fatigue, erosion, stress corrosion, surface heat welding and the like in the using process, so the service life of the die casting die is short. It is known that the failure of the mold is initiated from the surface first, and thus improving the surface texture and properties is effective in increasing the useful life of the mold.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a high-entropy alloy powder material, a preparation method and application of a cladding layer, obtains the well-formed cladding layer, improves the hardness and the high-temperature oxidation resistance of the material, prepares the high-entropy alloy cladding layer on the surface of H13 steel through a laser cladding process, and effectively improves the hardness and the high-temperature oxidation resistance of H13 steel, thereby prolonging the service life of the H13 steel and reducing the material cost consumption.

The technical purpose of the invention is realized by the following technical scheme:

the high-entropy alloy powder is composed of Fe, Co, Cr, Mn, Ni and Al element powder, namely the alloy powder composition is represented as FeCoCrNiMnAl, and specifically, the Fe, Co, Cr, Mn, Ni and Al are in equal molar ratio, namely the mole numbers of the six metal elements are consistent.

When the preparation is carried out, firstly, the proportion calculation is carried out according to the molar ratio of each element, the components are weighed accurately and then are fully mixed to be uniform, for example, the powder of each element is weighed by an electronic scale and is ground in a mortar to be uniformly mixed, and the grinding time is 0.5-1 hour. Wherein, the selected components are powder with the purity of more than or equal to 99 percent and the particle size of 200-300 meshes.

The alloy powder is applied to laser cladding welding, high-entropy alloy powder and ethanol are mixed and then uniformly coated on the surface of a base material, and a cladding layer can be obtained through laser cladding after drying.

The ethanol is analytically pure absolute ethanol, and consists of 92-95% of alloy powder and 5-8% of ethanol in a mixture of six-membered high-entropy alloy powder and ethanol in percentage by mass.

After mixing, forming paste or paste to be convenient for coating on the surface of the base material, and forming a prefabricated layer on the surface of the base material after coating, wherein the thickness of the prefabricated layer is 0.8-1.2 mm.

Wherein the substrate material is descaled and oil stain removed.

When laser cladding is carried out, H13 steel is selected as a base material, and the technological parameters are as follows: the laser power is 1300-1600 KW, the diameter of a light spot is 2.0-4.0 mm, the scanning speed is 5-7 mm/s, the defocusing amount is 6-10 mm, the protective gas is argon, nitrogen or helium, and the gas flow is 20-25L/min.

The technological parameters are as follows: the laser power is 1400-1500 KW, the diameter of a light spot is 2.0-4.0 mm, the scanning speed is 6-7 mm/s, the defocusing amount is 8-10 mm, the protective gas is argon, nitrogen or helium, and the gas flow is 20-25L/min.

Compared with the prior art, the invention has the following advantages:

(1) in the alloy powder, Cr is mainly used for improving the hardness of a cladding layer through solid solution strengthening and for improving the corrosion resistance of the cladding layer, and Al plays a role in solid solution strengthening in the system. The solid solution strengthening effect is good because the atomic radius is larger. The induced lattice distortion increases with increasing Al content. Further, Al and Cr form protective Al₂O₃、Cr₂O₃Further oxidation of the matrix can be prevented, and the oxidation rate of the alloy is reduced. In addition, the disorder degree of the laser cladding high-entropy alloy coating is larger, the coating becomes larger at high temperature, and the diffusion and redistribution rate among elements is remarkably reduced by the high mixed entropy effect, so that the phase structure in the coating is stable, the high-temperature hardness is basically kept unchanged, and the high-temperature softening resistance is good.

(2) The invention provides high-entropy alloy powder consisting of metal elements, and the self-fluxing property of the powder is improved.

(3) The invention prepares the cladding layer with good forming, higher hardness and better oxidation resistance, and the performance is obviously improved compared with the base material.

Drawings

FIG. 1 is a macroscopic morphology photograph (surface) of a FeCoCrNiMnAl cladding layer prepared by the present invention.

FIG. 2 is a photograph (cross section) of the overall appearance of a FeCoCrNiMnAl cladding layer prepared by the invention.

FIG. 3 is a photograph of the metallurgical structure of the FeCoCrNiMnAl cladding layer prepared by the invention.

Detailed Description

The technical scheme of the invention is further illustrated by the following specific examples:

the matrix material is H13 steel (purchased from Tianjin Yi iron and Steel Co., Ltd.), the mechanical polishing is adopted to remove oxides, the acetone is adopted to remove oil stains, and the chemical components are shown in the following table (mass fraction%) (the components meet the national standard):

the method is implemented according to the following steps:

1. the proportion of FeCoCrNiMnAl high-entropy alloy powder is calculated according to the molar ratio, the powder of various elements is weighed by an electronic scale and is ground in a mortar for half an hour to be uniformly mixed.

2. Mixing 92-95% of laser cladding powder and 5-8% of ethanol into paste or paste, coating the paste or paste on the surface of a base material, wherein the thickness of a prefabricated layer is 1-1.2 mm, and obtaining a cladding layer through laser cladding after air drying.

3. The selection laser used model JK2003SM Nd: YAG laser cladding.

4. The metallographic structure observation equipment adopts an OLYMPUS-GX 51 metallographic microscope, and the manufacturer comprises: olympus, Inc., Japan.