Additive manufacturing method for high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy

Abstract

The invention discloses an additive manufacturing method for a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy. The method comprises the following steps: S1, preparing ingredients according to a ratio of 40-60wt% 316L powder and 40-60wt% medium-entropy alloy NiCoCr powder to obtain a mixed powder; S2, drying the mixed powder, and pouring the dried mixed powder into a powder mixer for stirring and uniform mixing; S3, placing the uniformly stirred mixed powder into a laser additive manufacturing device for laser additive manufacturing to obtain the high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy; the process parameters of the laser additive manufacturing are: laser power of 150W-500W, scanning speed of 400-1400mm / s, interlayer spacing of 0.04-0.1mm, and layer thickness of 0.01-0.05mm; and argon is used as a shielding gas during the additive manufacturing process. The present invention can realize the processing and manufacturing of high-performance high-entropy alloys only through additive manufacturing. The prepared high-entropy alloys have high strength and excellent elongation-strength combination capabilities.

Description

Technical Field

[0001] The present invention relates to an additive manufacturing method for a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy, belonging to the field of new materials and processing technology. Background Art

[0002] With the development of human civilization and the advancement of science and technology, people have increasingly higher requirements for the performance of advanced structural materials. High-entropy alloys, a material born from a new design concept, are hailed as one of the three major breakthroughs in alloying theory in recent decades. High-entropy alloys are prepared using four or more elements in an equiatomic or nearly equiatomic manner. Their unique crystal structure makes the alloys less likely to form intermetallic compounds and have nano-precipitates between structures. They have demonstrated excellent properties in many aspects and have attracted considerable attention from scholars at home and abroad. Non-equiatomic high-entropy alloys have even better mechanical properties and have great application prospects as advanced structural materials. In the future, they may be widely used as key materials in some important industrial fields, such as defense, transportation, aerospace, and other fields.

[0003] Currently, the manufacture of high-entropy alloys (HEAs) is primarily performed using conventional processes. Laser additive manufacturing (LAM) offers the ability to create complex alloy structures. Furthermore, the resulting alloys exhibit superior mechanical properties. Consequently, additive manufacturing of HEAs has garnered significant attention in recent years. However, research on the additive manufacturing of HEAs with non-equiatomic ratios is limited. Summary of the Invention

[0004] The purpose of the present invention is to provide an additive manufacturing method for a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy. By optimizing the element ratio and additive manufacturing process, a non-equiatomic ratio high-entropy alloy with ultra-high strength and toughness is obtained.

[0005] The technical solution adopted by the present invention to achieve its invention object is: a method for additive manufacturing of a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy, the steps of which are as follows:

[0006] S1. Prepare mixed powder by mixing 40-60 wt% 316L powder and 40-60 wt% medium entropy alloy NiCoCr powder;

[0007] S2, drying the mixed powder, and pouring the dried mixed powder into a powder mixer for stirring and mixing;

[0008] S3, placing the evenly stirred mixed powder into a laser additive manufacturing device, and performing laser additive manufacturing to obtain a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy;

[0009] The laser additive manufacturing process parameters are: laser power 150W-500W, scanning speed 400-1400mm / s, layer spacing 0.04-0.1mm, and layer thickness 0.01-0.05mm; argon is used as the protective gas during the additive manufacturing process.

[0010] Furthermore, in step S2 of the present invention, the drying temperature for drying the mixed powder is 60-100° C., and the drying time is 1-3 hours.

[0011] Furthermore, in step S2 of the present invention, the dried mixed powder is poured into a powder mixer for stirring and mixing for 3 to 6 hours.

[0012] Furthermore, the process parameters of the laser additive manufacturing device in step S3 of the present invention are: laser power 200W-300W, scanning speed 500-700mm / s, layer spacing 0.07-0.09mm, and layer thickness 0.02-0.04mm.

[0013] Furthermore, the process parameters of the laser additive manufacturing device in step S3 of the present invention are: laser power 250 W, scanning speed 600 mm / s, layer spacing 0.08 mm, and layer thickness 0.03 mm.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention pre-mixes 316L stainless steel and CrCoNi medium-entropy alloy powders, and then processes them through additive manufacturing to obtain high-entropy alloys with different compositions, thereby achieving in-situ regulation of the high-entropy alloy composition and providing an effective technical path for additive manufacturing of high-entropy alloys.

[0016] 2. The present invention realizes in-situ control of microstructure, providing a new path for realizing non-equiatomic high entropy alloys with the ability to combine ultra-high strength and toughness.

[0017] 3. The present invention can realize the processing and manufacturing of high-performance high-entropy alloys only through additive manufacturing, which greatly reduces the processing time compared with traditional processing methods and is expected to realize the structural integrated manufacturing of large and complex key equipment.

[0018] Fourth, the 316L powder used in this invention contains a small amount of silicon, which promotes the formation of precipitated phases. Furthermore, the high-entropy effect destabilizes the solid solution, further promoting the transition from crystalline to amorphous. Furthermore, the rapid solidification, thermal stress, and high dislocation density during the additive manufacturing process also contribute to the formation of amorphous precipitated phases. Therefore, the non-equiatomic FeCoCrNi high-entropy alloy prepared in this invention contains a large number of precipitated phases, which contributes to the enhanced mechanical properties of the high-entropy alloy.

[0019] 5. By controlling the specific parameters of additive manufacturing, the present invention adopts a low heat input of 150W-500W, a high-speed printing of 400-1400mm / s, a layer spacing of 0.04-0.1mm and a layer thickness of 0.01-0.05mm, and obtains a high-entropy alloy with fine grains, high dislocation density, and a large amount of precipitated phases. These unique structures are conducive to improving the strength of the high-entropy alloy.

[0020] In summary, the high-entropy alloy prepared by the present invention has excellent mechanical properties, with a strength of up to 550 MPa, an elongation of 44%, and an excellent elongation-strength combination ability.

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an electron backscattered image of the grain morphology and grain size distribution of the FeCoCrNi high-entropy alloy prepared in Example 1 of the present invention.

[0023] Figure 2 This is an electron microscope image of the material microstructure of the FeCoCrNi high entropy alloy prepared in Example 1 of the present invention.

[0024] Figure 3 This is a composition analysis diagram of the matrix and precipitated phase of the FeCoCrNi high-entropy alloy prepared in Example 1 of the present invention.

[0025] Figure 4 This is a statistical result diagram of the precipitate phase size and spacing of the FeCoCrNi high entropy alloy prepared in Example 1 of the present invention.

[0026] Figure 5 This is the engineering stress-strain curve of the FeCoCrNi high entropy alloy prepared in Example 1 of the present invention.

[0027] Figure 6 This is a statistical graph of the elongation-strength of the FeCoCrNi high entropy alloy prepared in Example 1 of the present invention and the FeCoCrNi alloy in the prior art. DETAILED DESCRIPTION

[0028] Example 1

[0029] A method for additive manufacturing of a high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy, comprising the following steps:

[0030] S1. Prepare mixed powder by mixing 50 wt% 316L powder and 50 wt% medium entropy alloy NiCoCr powder;

[0031] S2, drying the mixed powder, and pouring the dried mixed powder into a powder mixer for stirring and mixing;

[0032] S3, placing the evenly stirred mixed powder into a laser additive manufacturing device, and performing laser additive manufacturing to obtain a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy;

[0033] The process parameters of the laser additive manufacturing are: laser power 250 W, scanning speed 600 mm / s, layer spacing 0.08 mm, and layer thickness 0.03 mm; argon is used as the protective gas during the additive manufacturing process.

[0034] In this example, the drying temperature for drying the mixed powder in step S2 is 60° C. and the drying time is 1 hour.

[0035] In step S2 of this example, the dried mixed powder is poured into a powder mixer for stirring and mixing for 4 hours.

[0036] Figure 1 The electron backscattered image and grain size distribution diagram of the FeCoCrNi high entropy alloy prepared in this embodiment. Among them, (a) is the electron backscattered image of the grain morphology of the FeCoCrNi high entropy alloy. From this figure, it can be seen that the grains of the FeCoCrNi high entropy alloy are of different sizes and the morphology of the grains is irregular, which is related to the solidification rate and thermal gradient in the additive manufacturing process. (b) is the statistically obtained grain size distribution diagram. It can be seen that there are a large number of small grains (<3μm) in the FeCoCrNi high entropy alloy. This is due to the presence of a large number of small-angle grain boundaries such as dislocations in the material. According to statistical results, the average grain size is 9μm. Figure 2 for Figure 2 The following are electron microscope images of the microstructure of the FeCoCrNi high-entropy alloy prepared in this embodiment. (a) is the overall morphology, which contains a large number of dislocation structures, forming a layered dislocation structure; (b) is a local morphology, showing that the FeCoCrNi high-entropy alloy material contains a large number of precipitates, which has not been reported in FeCoCrNi high-entropy alloys in the prior art; (c) is the morphology of one of the precipitates and the diffraction spots in different regions. The precipitate is circular, with crystals at the circumference and amorphous at the center.

[0037] Figure 3 This is a composition analysis diagram of the matrix and precipitate phase of the FeCoCrNi high-entropy alloy prepared in this example. Two precipitate phases were selected and their compositions were studied using line scanning mode. It was found that the main component of the matrix contained FeCoCrNi, and the precipitate phase components were Si and O. Figure 4Figure 1 shows the statistical results of the size and spacing of the precipitated phases of the FeCoCrNi high-entropy alloy prepared in this example. (a) shows the statistical results of the precipitated phase size of the FeCoCrNi high-entropy alloy obtained based on the transmission electron microscopy results. It can be seen from the figure that the average value of the precipitated phase size is 58nm, and (b) shows the statistical results of the spacing of the precipitated phases of the FeCoCrNi high-entropy alloy. It can be seen from the figure that the average spacing of the precipitated phases is 208nm. Figure 5 The engineering stress-strain curve of the FeCoCrNi high-entropy alloy prepared in this embodiment is shown in the figure. As can be seen from the figure, the high-entropy alloy prepared in this embodiment can reach a strength of 550 MPa and an elongation of up to 44%, showing excellent mechanical properties. Figure 6 This is a statistical graph of the elongation-strength relationship between the FeCoCrNi high-entropy alloy prepared in this example and a prior art FeCoCrNi alloy. The graph compares the mechanical properties of the non-equiatomic FeCoCrNi high-entropy alloy prepared in this example with an equiatomic FeCoCrNi alloy prepared using different parameters using prior art additive manufacturing techniques. The FeCoCrNi high-entropy alloy prepared in this example exhibits the best elongation-strength combination.

[0038] Example 2

[0039] A method for additive manufacturing of a high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy, comprising the following steps:

[0040] S1. Prepare mixed powder by mixing 40 wt% 316L powder and 60 wt% medium entropy alloy NiCoCr powder;

[0041] S2, drying the mixed powder, and pouring the dried mixed powder into a powder mixer for stirring and mixing;

[0042] S3, placing the evenly stirred mixed powder into a laser additive manufacturing device, and performing laser additive manufacturing to obtain a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy;

[0043] The process parameters of the laser additive manufacturing are: laser power 200 W, scanning speed 500 mm / s, layer spacing 0.07 mm, and layer thickness 0.02 mm; argon is used as the protective gas during the additive manufacturing process.

[0044] In this example, the drying temperature for drying the mixed powder in step S2 is 60° C. and the drying time is 3 hours.

[0045] In step S2 of this example, the dried mixed powder is poured into a powder mixer for stirring and mixing for 6 hours.

[0046] Example 3

[0047] A method for additive manufacturing of a high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy, comprising the following steps:

[0048] S1. Prepare mixed powder by mixing 60 wt% 316L powder and 40 wt% medium entropy alloy NiCoCr powder;

[0049] S2, drying the mixed powder, and pouring the dried mixed powder into a powder mixer for stirring and mixing;

[0050] S3, placing the evenly stirred mixed powder into a laser additive manufacturing device, and performing laser additive manufacturing to obtain a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy;

[0051] The process parameters of the laser additive manufacturing are: laser power 300 W, scanning speed 700 mm / s, layer spacing 0.09 mm, and layer thickness 0.04 mm; argon is used as the protective gas during the additive manufacturing process.

[0052] In this example, the drying temperature of step S2 for drying the mixed powder is 100° C. and the drying time is 1 hour.

[0053] In step S2 of this example, the dried mixed powder is poured into a powder mixer for stirring and mixing for 3 hours.

Claims

1. A method for additive manufacturing of a high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy, comprising the following steps: S1. Prepare mixed powder by mixing 40-60 wt% of 316L powder and 40-60 wt% of medium entropy alloy NiCoCr powder; S2, drying the mixed powder, and pouring the dried mixed powder into a powder mixer for stirring and mixing; S3, placing the evenly stirred mixed powder into a laser additive manufacturing device, and performing laser additive manufacturing to obtain a high-strength and tough non-equiatomic ratio FeCoCrNi high-entropy alloy; The process parameters of the laser additive manufacturing are: laser power 200W-300W, scanning speed 500-700mm / s, layer spacing 0.07-0.09mm, and layer thickness 0.02-0.04mm; argon is used as the protective gas during the additive manufacturing process.

2. The additive manufacturing method of a high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy according to claim 1, characterized in that: In step S2, the mixed powder is dried at a temperature of 60-100° C. and for a time of 1-3 hours.

3. The additive manufacturing method of a high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy according to claim 1, characterized in that: In step S2, the dried mixed powder is poured into a powder mixer and stirred for 3 to 6 hours.

4. The additive manufacturing method of a high-strength and high-toughness non-equiatomic ratio FeCoCrNi high-entropy alloy according to claim 1, characterized in that: The process parameters of the laser additive manufacturing in step S3 are: laser power 250 W, scanning speed 600 mm / s, layer spacing 0.08 mm, and layer thickness 0.03 mm.

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