A method for preparing NiTiCu alloy powder with different particle sizes

Abstract

The present invention belongs to the field of powder metallurgy, and specifically relates to a method for preparing NiTiCu alloy powders of different particle sizes, including mixing three single metal powders of Ni, Ti and Cu in proportion, dividing the initial mixed powder into four parts, performing ball milling mixing for different times respectively, taking out the powders after the ball milling in turn, and drying them, selecting corresponding screens for sieving according to the particle size of the powder after drying, mixing the sieved powders, and obtaining NiTiCu alloy powders of different particle sizes. The present invention controls the ball milling time and ball milling method in batches during the ball milling process, and finally selects targeted screens for different batches of ball milled mixed powders to obtain NiTi alloys of different particle sizes, and provides a NiTiCu powder alloy preparation process with uniform particle size, stable composition, and low counterfeiting cost by optimizing parameter control and process flow during the alloying process.

Description

Technical Field

[0001] The invention belongs to the field of powder metallurgy, and in particular relates to a method for preparing NiTiCu alloy powders with different particle sizes. Background Art

[0002] NiTi alloy is one of the most widely used shape memory alloys, however, its elasticity and memory properties still have room for improvement. In recent years, NiTiCu alloy has attracted much attention as a potential alternative. NiTiCu alloy has excellent performance in shape memory and superelasticity, which makes it have great application potential in medical, aerospace and other fields

[0003] NiTiCu alloy refers to a metal obtained by mixing three elements of Ni, Ti and Cu in a fixed ratio. The content of Cu element includes 5%, 10%, 20% and the like according to the use environment. At present, one of the most commonly used methods for preparing NiTiCu alloy is powder metallurgy technology. NiTiCu powder alloys with uniform structure and good stability can be prepared by powder metallurgy technology to meet the requirements of material properties in different fields. However, the existing NiTiCu powder alloying method still has some challenges and limitations in terms of particle size control, alloy composition uniformity and alloying efficiency. Therefore, it is necessary to develop a new method for preparing NiTiCu powder alloy to improve its performance and application range.

[0004] At present, the experiments mainly use pre-alloyed high NiTiCu alloy powder. Commercial NiTiCu powder is rare and expensive, and needs to be customized, with a long waiting period and high cost. Summary of the invention

[0005] The invention provides a method for preparing NiTiCu alloy powders with different particle sizes, so as to solve the problems in the prior art that NiTiCu powders have few varieties, are expensive, need to be customized and have a long waiting period.

[0006] To achieve the above object, the present invention proposes the following technical solutions:

[0007] A method for preparing NiTiCu alloy powders with different particle sizes comprises the following steps:

[0008] Step 1, mixing single metal powders of Ni, Ti and Cu to obtain an initial mixed powder, wherein the atomic percentages of the three single metal powders of Ni, Ti and Cu are 49-50at%, 44-45at% and 5-7at% respectively;

[0009] Step 2, dividing the initial mixed powder into four equal parts, recorded as the first powder, the second powder, the third powder and the fourth powder; ball milling the first powder, the second powder, the third powder and the fourth powder for different time periods, and the mixing time ratio is 1:2:3:4;

[0010] Step 3, taking out the first powder, the second powder, the third powder and the fourth powder after ball milling in sequence, and drying them;

[0011] Step 4: According to the particle sizes of the first powder, the second powder, the third powder and the fourth powder after drying, corresponding sieves are selected for sieving to obtain NiTiCu alloy powders with different particle sizes.

[0012] Preferably, the method further comprises step 5, sequentially performing laser melting on NiTiCu alloy powders of different particle sizes to obtain NiTiCu alloy; specifically, comprising:

[0013] Step 5.1, building a three-dimensional model;

[0014] Step 5.2, slice the 3D model and import it into the 3D printer;

[0015] Step 5.3, path planning for laser scanning;

[0016] Step 5.4, according to the sliced ​​model and the planned path, the NiTiCu alloy powders of different particle sizes are processed in sequence by 3D printing layer by layer to obtain the NiTiCu shape memory alloy.

[0017] Preferably, in step 1, the atomic percentages of the three elemental metal powders of Ni, Ti and Cu are specifically 50 at%, 45 at% and 5 at%.

[0018] Preferably, in step 1, the single metal powders of Ni, Ti and Cu are dried before mixing.

[0019] Preferably, the specific process of the drying is:

[0020] The single metal powders of Ni, Ti and Cu are placed in a vacuum dryer for drying at a temperature of 80-90°C and a heating time of 2-3h.

[0021] Preferably, in step 2, the ball milling mixing time for the first powder, the second powder, the third powder and the fourth powder is 10 h, 20 h, 30 h and 40 h respectively.

[0022] Preferably, in step 4, the first powder after drying is sieved using a 200-mesh sieve;

[0023] The dried second powder is sieved using a 200-mesh sieve and a 150-mesh sieve in sequence;

[0024] The dried third powder is sieved using a 150-mesh sieve and a 100-mesh sieve in sequence;

[0025] The dried fourth powder was sieved using a 200-mesh sieve.

[0026] Preferably, the first powder after sieving is a NiTiCu alloy powder with a particle size of 15-53 μm;

[0027] The second powder after sieving is a NiTiCu alloy powder with a particle size of 53-105 μm;

[0028] The third powder after sieving is a NiTiCu alloy powder with a particle size of 105-200 μm;

[0029] The fourth powder after sieving is a NiTiCu alloy powder having a particle size of more than 200 μm.

[0030] Preferably, the ball milling mixing in step 2 is low-speed ball milling mixing, specifically:

[0031] The ball mill speed was 300 r / min, and it rotated alternately left and right, with a replacement time of every 30 minutes.

[0032] Preferably, the ball milling mixing in step 2 uses zirconia grinding balls with a particle size of 2 mm, and the ball-to-powder ratio is 20:1.

[0033] The present invention is beneficial in that:

[0034] The present invention provides a method for preparing NiTiCu alloy powders with different particle sizes, by mixing three elemental metal powders of Ni, Ti and Cu in proportion, controlling the ball milling time and ball milling method in batches during the ball milling process, and finally selecting targeted screens for different batches of ball milled mixed powders to obtain NiTi alloys with different particle sizes. The present invention provides a preparation process of NiTiCu powder alloys with uniform particle size, stable composition and low cost by optimizing parameter control and process flow during the alloying process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0036] Figure 1 It is a schematic diagram of a process for preparing NiTiCu alloy powders with different particle sizes;

[0037] Figure 2This is a schematic diagram of the first powder after drying in Example 1;

[0038] Figure 3 This is a schematic diagram of the second powder after drying in Example 1;

[0039] Figure 4 This is a schematic diagram of the third powder after drying in Example 1;

[0040] Figure 5 This is a schematic diagram of the fourth powder after drying in Example 1;

[0041] Figure 6 Laser scanning path;

[0042] Figure 7 The NiTi alloy is printed using the second powder;

[0043] Figure 8 Original NiTi shape memory alloy prepared for 3D printing technology. DETAILED DESCRIPTION

[0044] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0045] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0046] See also Figure 1 As shown, the present invention provides a method for preparing NiTiCu alloy powders with different particle sizes, comprising the following steps:

[0047] Step 1, mixing the original elemental metal powder of NiTiCu alloy to obtain an initial mixed powder:

[0048] Prepare three kinds of metal powders, Ni, Ti, and Cu, and dry them at a temperature of 80-90°C for 2-3 hours to ensure the fluidity of the powders and avoid the interference of excess water that causes the powders to agglomerate and affect the alloying results of the materials;

[0049] Then, the three metal powders of Ni, Ti and Cu are mixed according to a certain proportion to obtain an initial mixed powder;

[0050] Specifically, Ni, Ti, and Cu powders are mixed in a ratio of 49-50 at %, 44-45 at %, and 5-7 at %.

[0051] Step 2: low speed ball milling of the initial mixed powder:

[0052] The initial mixed powder was divided into four parts, namely the first powder, the second powder, the third powder and the fourth powder, and the above powders were ball-milled for 10 h, 20 h, 30 h and 40 h respectively;

[0053] The parameters in the ball milling mixing process are:

[0054] The grinding balls used are 2mm-diameter zirconium oxide grinding balls, with a ball-to-powder ratio of 20:1;

[0055] The ball mill speed was 300 r / min, and it rotated alternately left and right, with a replacement time of every 30 minutes.

[0056] Step 3, after the ball milling is completed, the first powder, the second powder, the third powder and the fourth powder are taken out in turn and dried in a vacuum dryer at a temperature of 80-90° C. for a heating time of 2-3 hours to ensure the fluidity of the powder and avoid the interference of excess water causing the powder to agglomerate and affect the alloying result of the material.

[0057] Step 4, sieving the powder after ball milling and mixing with a sieve to obtain NiTiCu alloy powders of different particle sizes:

[0058] The dried first powder is sieved using a 200-mesh screen to obtain a NiTiCu alloy powder with a particle size of 15-53 μm;

[0059] The dried second powder is sieved using a 200-mesh sieve and a 150-mesh sieve in sequence to obtain a NiTiCu alloy powder with a particle size of 53-105 μm;

[0060] The dried third powder is sieved using a 150-mesh sieve and a 100-mesh sieve in sequence to obtain a NiTiCu alloy powder with a particle size of 105-200 μm;

[0061] The dried fourth powder is sieved using a 200-mesh screen to obtain a NiTiCu alloy powder having a particle size of more than 200 μm;

[0062] The NiTiCu alloy powders are mixed to obtain NiTiCu alloy powders with different particle sizes.

[0063] In a specific embodiment, the three elemental metal powders are all spherical powders, and the particle size of the spherical powders is 12-52 μm.

[0064] In a specific embodiment, in step 1, the ratio of the mixed powders is 50at%, 45at%, and 5at%;

[0065] In a specific embodiment, the powder particle size may change with different ball milling mixing times. The ball milling mixing time may be freely set based on the target size.

[0066] In a specific embodiment, the sieved first powder, second powder, third powder and fourth powder are respectively prepared by laser melting to obtain NiTiCu alloy.

[0067] In step 5, the specific process of laser melting preparation is:

[0068] The mixed powder was placed on a stainless steel plate and prepared using a laser melting manufacturing device. During the preparation process, the scanning spacing was 0.08 mm and the powder layer thickness was 0.03 mm.

[0069] This printing takes NiTiCu powder ball-milled for 20 hours as an example, and the process is as follows:

[0070] Build a three-dimensional model of the sample and print an 8*8*8 cube;

[0071] (2) The model is sliced ​​into layers with a thickness of 0.03 mm and imported into a 3D printer;

[0072] (3) Perform path planning; the laser scanning strategy used includes: dividing the processing template into the smallest unit of 3*3mm. The laser beam moves in an S-shape along the y-axis. Figure 6 As shown;

[0073] (4) Printing NiTiCu shape memory alloy layer by layer using 3D printing. Figure 7 As shown;

[0074] The laser scanning is to decompose the scanning area into the smallest unit cell of 3mm*3mm, and the laser scanning in the processing process is an S-shaped motion along the y-axis. The purpose of this is to effectively reduce the heat accumulation of the laser scanning in the scanning area, while ensuring good metallurgical bonding of the molten pool, to achieve effective dissipation of residual heat and avoid heat accumulation.

[0075] The above method achieves good forming effect of 3D printing NiTi series alloys, and cracks and thermal deformation are reduced. The forming effect of NiTi alloys prepared by non-optimized methods is poor, that is, if the batch milling method in this method is not used to process the raw materials, the cracks and thermal deformation of the final product will be more obvious, such as Figure 8 shown.

[0076] Step 1: Dry the original single metal powders of Ni, Ti, and Cu with a particle size of 12 to 52 μm at 90° C. for 2 h, and then mix them according to the atomic percentage of 50 at%, 45 at%, and 5 at% to obtain an initial mixed powder.

[0077] Step 2, the initial mixed powder is divided into a first powder, a second powder, a third powder and a fourth powder according to the mass, and the powder is respectively subjected to low-speed ball milling and mixing. The grinding balls used in the ball milling and mixing process are 2 mm-diameter zirconium oxide grinding balls, and the ball-to-powder ratio is 20:1; the ball milling speed is 300 r / min, and the left and right alternating rotation is adopted, and the replacement time is once every 30 minutes;

[0078] The ball milling time of the first powder, the second powder, the third powder and the fourth powder are 10 h, 20 h, 30 h and 40 h respectively.

[0079] Step 3: Take out the first powder after ball milling for 10 hours, and dry it in a vacuum dryer at 90° C. for 2 hours.

[0080] Step 4: Take out the second powder after ball milling for 20 hours and dry it in a vacuum dryer at 90° C. for 2 hours.

[0081] Step 5: Take out the third powder after ball milling for 30 hours and dry it in a vacuum dryer at 90° C. for 2 hours.

[0082] Step 6: Take out the fourth powder after ball milling for 40 hours and dry it in a vacuum dryer at 90° C. for 2 hours.

[0083] The first powder, the second powder, the third powder and the fourth powder after drying are respectively as follows Figure 2 , 3 , 4, and 5.

[0084] Step 7, the first powder after drying is sieved using a 200-mesh sieve, the second powder after drying is sieved using a 200-mesh sieve and a 150-mesh sieve in sequence, the third powder after drying is sieved using a 150-mesh sieve and a 100-mesh sieve in sequence, and the fourth powder after drying is sieved using a 200-mesh sieve to obtain NiTiCu alloy powders of 50 μm, 100 μm, 150 μm, and 200 μm in sequence, and the above alloy powders are mixed to obtain NiTiCu alloy powders of different particle sizes.

[0085] The present invention proposes to mix three kinds of powders of Ni, Ti and Cu in the proportion of 50at%, 45at% and 5at%, and to use a drying box to dehydrate the powders in order to ensure the fluidity of the powders and avoid the interference of excess water causing the powders to agglomerate and affect the alloying result of the material. In addition, the ball milling time and ball milling method are controlled during the ball milling process to obtain an alloyed NiTiCu alloy. Finally, NiTi alloys of different particle sizes can be obtained through a filter screen.

[0086] By optimizing the parameter control and process flow in the alloying process, the present invention realizes the preparation of NiTiCu alloy powder with uniform particle size, stable composition and relatively low price. This method will provide new ideas and technical support for the further development of the NiTiCu alloy field and promote the wide application and promotion of NiTiCu alloy in various application fields.

[0087] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing NiTiCu alloy powders of different particle sizes, characterized in that: The steps include: Step 1, mixing single metal powders of Ni, Ti and Cu to obtain an initial mixed powder, wherein the atomic percentages of the three single metal powders of Ni, Ti and Cu are 49-50at%, 44-45at% and 5-7at% respectively; In the step 1, the single metal powders of Ni, Ti and Cu are dried before mixing; Step 2, dividing the initial mixed powder into four equal parts, recorded as the first powder, the second powder, the third powder and the fourth powder; ball milling the first powder, the second powder, the third powder and the fourth powder for different time periods, and the mixing time ratio is 1:2:3:4; In the step 2, the ball milling mixing time of the first powder, the second powder, the third powder and the fourth powder are 10 hours, 20 hours, 30 hours and 40 hours respectively; Step 3, taking out the first powder, the second powder, the third powder and the fourth powder after ball milling in sequence, and drying them; Step 4, according to the particle sizes of the first powder, the second powder, the third powder and the fourth powder after drying, select corresponding sieves for sieving to obtain NiTiCu alloy powders of different particle sizes, and mix the first powder, the second powder, the third powder and the fourth powder to obtain a mixed powder; In the step 4, the dried first powder is sieved using a 200-mesh sieve; The dried second powder is sieved using a 200-mesh sieve and a 150-mesh sieve in sequence; The dried third powder is sieved using a 150-mesh sieve and a 100-mesh sieve in sequence; The dried fourth powder is sieved using a 200-mesh sieve; The first powder after sieving is a NiTiCu alloy powder with a particle size of 15-53 μm; The second powder after sieving is a NiTiCu alloy powder with a particle size of 53-105 μm; The third powder after sieving is a NiTiCu alloy powder with a particle size of 105-200 μm; The fourth powder after sieving is a NiTiCu alloy powder with a particle size of more than 200 μm; The method further comprises step 5, performing laser melting on the mixed powder to obtain a NiTiCu alloy; specifically, comprising: Step 5.1, building a three-dimensional model; Step 5.2, slice the 3D model and import it into the 3D printer; Step 5.3, path planning for laser scanning, the laser beam moves in an S-shape along the y-axis; Step 5.4, according to the sliced ​​model and the planned path, the mixed powder is processed by 3D printing layer by layer to obtain NiTiCu shape memory alloy.

2. The method for preparing NiTiCu alloy powders of different particle sizes according to claim 1, characterized in that: In step 1, the atomic percentages of the three elemental metal powders of Ni, Ti and Cu are specifically 50 at%, 45 at% and 5 at%.

3. The method for preparing NiTiCu alloy powders of different particle sizes according to claim 1, characterized in that: The specific process of the drying is as follows: The single metal powders of Ni, Ti and Cu are placed in a vacuum dryer for drying at a temperature of 80-90°C and a heating time of 2-3h.

4. The method for preparing NiTiCu alloy powders of different particle sizes according to claim 1, characterized in that: The ball milling mixing in step 2 is low-speed ball milling mixing, specifically: The ball mill speed was 300 r / min, and it rotated alternately left and right, with a replacement time of every 30 minutes.

5. The method for preparing NiTiCu alloy powders of different particle sizes according to claim 1, characterized in that: The ball milling mixing in step 2 uses zirconia grinding balls with a particle size of 2 mm, and the ball-to-powder ratio is 20:1.

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