TC4-Cu alloy powder and selective laser melting forming method thereof

Abstract

The invention provides TC4-Cu alloy powder and a selective laser melting forming method thereof. The TC4-Cu alloy powder comprises the following components in percentage by mass: 6wt% of Al powder, 4wt% of V powder, xwt% of Cu powder and the balance of Ti powder, and x is equal to 3-5. The adopted TC4-Cu alloy powder is formed, a CuTi2 phase is generated, and the hardness, the yield strength, the tensile strength and the wear resistance of the TC4 alloy are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal additive manufacturing, and specifically relates to a TC4-Cu alloy powder and a selective laser melting molding method thereof. Background Art

[0002] Selective laser melting (SLM) is an advanced additive manufacturing (AM) technology that integrates multiple disciplines such as computers, materials, and machinery. Selective laser melting uses a high-energy laser beam to melt powder layer by layer to build a three-dimensional entity. This technology can produce parts with complex three-dimensional structures without the use of any molds. Due to its one-piece molding characteristics, it greatly reduces the time spent on cutting, assembly and other processes in traditional subtractive manufacturing, shortens the manufacturing time of parts, and increases the utilization rate of materials, achieving personalized customization.

[0003] Pure titanium has high plasticity but low strength, which limits its application range. In order to improve its performance, the most effective way is to alloy pure titanium, that is, to add some suitable alloying elements to pure titanium to form titanium alloy. These elements usually have a certain strengthening effect in the process of metallurgical bonding with pure titanium, thereby effectively improving the mechanical properties of pure titanium. Elements that undergo eutectoid transformation with Ti and expand the β phase region are called eutectoid β stabilizing elements. Common inactive eutectoid elements include Cr, Mn, Fe, etc. The eutectoid transformation temperature of these elements with Ti is low and difficult to proceed under normal conditions; active eutectoid elements include Si, Cu, H, Ni, Ag, etc. The eutectoid transformation of these elements with Ti is extremely fast. Adding eutectoid elements can usually improve the strength of the alloy, but it will reduce plasticity under certain conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a TC4-Cu alloy powder formula and a laser selective melting forming method.

[0005] By optimizing the alloy formula and adding spherical Cu powder to the TC4 alloy powder, TC4-Cu alloy samples with higher density were prepared, which can effectively improve the hardness, tensile strength and wear resistance of the material.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A TC4-Cu alloy powder, wherein the TC4-Cu alloy powder comprises, based on 100% by mass, 3-5wt% Cu powder and the remainder TC4 powder.

[0007] The Cu powder and TiC4 powder are solid spherical powders with a powder particle size of 15-53 μm.

[0008] A selective laser melting method for TC4-Cu alloy powder comprises the following steps: (1) Put Ti powder, Al powder, V powder and Cu powder into a ball mill and mix them evenly using a ball mill; (2) placing the mixed powder obtained in step (1) into a drying oven for drying; (3) vibrating and sieving the powder obtained in step (2); (4) The powder obtained in step (3) is placed in a metal additive manufacturing device for molding.

[0009] Furthermore, in step (2), argon gas was introduced into the ball mill as a protective gas, the rotation speed of the ball mill was 200 r / min, the ball-to-material ratio was 3:1, and the ball milling time was 3 h.

[0010] Furthermore, in step (2), the drying box is evacuated before drying, the drying temperature is 80° C., and the drying time is 8 hours.

[0011] Furthermore, in step (3), the mesh size of the sieve used for vibration sieving is 200 meshes, the vibration time is 10 minutes, the vibration frequency is 50 Hz, and the amplitude is 1 mm.

[0012] Furthermore, the specific process parameters of the molding in step (4) are: scanning speed of 950-1550 mm / s, laser power of 130-250 W, powder thickness of 30 μm, scanning spacing of 100 μm, adjacent powder layer scanning angles rotated by 67°, TC4 substrate selected as the molding substrate, substrate preheating temperature of 200°C, argon as the protective gas in the molding chamber, and oxygen concentration in the molding chamber less than 100 ppm.

[0013] Beneficial effects of the present invention: (1) The powders used are all solid spherical powders with a size of 15-53 μm. High-energy ball milling can make the alloy powders more evenly mixed and improve the molding quality. Argon is introduced into the ball mill as a protective gas to reduce the oxidation of the alloy powders.

[0014] (2) The present invention uses selective laser melting technology to form the alloy powder. During the selective laser melting forming process, a CuTi2 phase is generated in situ. The test results show that after adding Cu, the hardness of the titanium alloy is improved while also improving its yield strength, tensile strength and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The SEM morphology image and particle size distribution histogram of the powder (after mixing) used in Example 1 of the present invention, (a) powder morphology image, (b) powder particle size distribution histogram.

[0016] Figure 2 This is the microstructure diagram of the sample formed by laser selective melting in Example 1.

[0017] Figure 3 This is the microstructure diagram of the laser selective melting molded sample in Example 2.

[0018] Figure 4 This is the microstructure diagram of the laser selective melting molded sample of comparative example 1.

[0019] Figure 5 It is the surface total spectrum of Example 1 (a), Example 2 (b), and Comparative Example 1 (c).

[0020] Figure 6 Friction coefficient diagram for friction and wear.

[0021] Figure 7 The XRD diffraction patterns of Example 1, Example 2 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0022] In order to make the above features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description. The methods of the present invention are all conventional methods in the art unless otherwise specified.

[0023] The model of the selective laser melting forming equipment in the following embodiments is SLM125H1.

[0024] The specific composition of the TC4 alloy powder used in the following examples and comparative examples is shown in Table 1.

[0025] Table 1 Chemical composition of TC4 alloy powder (mass fraction / %) Example 1 (1) Cu powder and TC4 powder (powder particle size is 15-53 μm) were weighed out according to the ratio of 5wt%Cu+95wt%TC4 alloy, and put into a ball mill for ball milling. Argon was introduced into the ball mill as a protective gas. The ball mill speed was 200 r / min, the ball-to-material ratio was 3:1, and the ball milling time was 3 h.

[0026] (2) The powder obtained in step (1) was placed in a vacuum drying oven, the drying temperature was set to 80°C, and the drying time was 8 hours.

[0027] (3) Place the dried powder into a 200-mesh sieve and vibrate for ten minutes at a frequency of 50 Hz and an amplitude of 1 mm.

[0028] (4) The powder sieved out in step (3) was subjected to selective laser melting molding, and the molding parameters were: laser power of 160 W, scanning speed of 1250 mm / s, scanning spacing of 100 μm, powder thickness of 30 μm, substrate of TC4 alloy substrate, substrate preheating temperature of 200 °C, adjacent powder layer scanning angle rotated 67°, and the molding chamber used argon gas with an oxygen content of less than 100 ppm.

[0029] The density of the prepared sample is 98.80%, and the mechanical properties are as follows: hardness 471.2Hv, tensile strength: 938.08Mpa, yield strength: 783.01Mpa, elongation 1.49%, and average friction coefficient 0.32.

[0030] Example 2 (1) Cu powder and TC4 powder (powder particle size is 15-53 μm) were weighed out according to the ratio of 3wt%Cu+97wt%TC4 alloy, and put into a ball mill for ball milling. Argon was introduced into the ball mill as a protective gas. The ball mill speed was 200 r / min, the ball-to-material ratio was 3:1, and the ball milling time was 3 h.

[0031] (2) The powder obtained in step (1) was placed in a vacuum drying oven, the drying temperature was set to 80°C, and the drying time was 8 hours.

[0032] (3) Place the dried powder into a 200-mesh sieve and vibrate for ten minutes at a frequency of 50 Hz and an amplitude of 1 mm.

[0033] (4) The powder sieved out in step (3) was subjected to selective laser melting molding, and the molding parameters were: laser power of 160 W, scanning speed of 1250 mm / s, scanning spacing of 100 μm, powder thickness of 30 μm, substrate of TC4 alloy substrate, substrate preheating temperature of 200 °C, adjacent powder layer scanning angle rotated 67°, and the molding chamber used argon gas with an oxygen content of less than 100 ppm.

[0034] The density of the prepared sample is 98.30%, and the mechanical properties are as follows: hardness 435.6Hv, tensile strength: 837.68Mpa, yield strength: 724.31Mpa, elongation 1.79%, and average friction coefficient 0.41.

[0035] Comparative Example 1 (1) Cu powder and TC4 powder were weighed out according to the ratio of 0wt%Cu+100wt%TC4 alloy, and put into a ball mill for ball milling. Argon was introduced into the ball mill as a protective gas. The ball mill speed was 200r / min, the ball-to-material ratio was 3:1, and the ball milling time was 3h.

[0036] (2) The powder obtained in step (1) was placed in a vacuum drying oven, the drying temperature was set to 80°C, and the drying time was 8 hours.

[0037] (3) Place the dried powder into a 200-mesh sieve and vibrate for ten minutes at a frequency of 50 Hz and an amplitude of 1 mm.

[0038] (4) The powder sieved out in step (3) was subjected to selective laser melting molding, and the molding parameters were: laser power of 160 W, scanning speed of 1250 mm / s, scanning spacing of 100 μm, powder thickness of 30 μm, substrate of TC4 alloy substrate, substrate preheating temperature of 200 °C, adjacent powder layer scanning angle rotated 67°, and the molding chamber used argon gas with an oxygen content of less than 100 ppm.

[0039] The density of the prepared sample is 98.00%, and the mechanical properties are as follows: hardness 355.3Hv, tensile strength: 738.61Mpa, yield strength: 599.60Mpa, elongation 9.05%, and average friction coefficient 0.56.

[0040] The morphology and particle size distribution histogram of the TC4-Cu alloy powder of Example 1 are as follows: Figure 1 As shown, it can be seen that the particle size of TC4-Cu alloy powder is relatively uniform, and most of the powder morphology is uniformly spherical.

[0041] The optical microscope surface image of Example 1 is as follows Figure 2 As shown in the figure, it can be seen that the sample has a good molding morphology. The optical microscope surface image of Example 2 is as follows Figure 3 As shown, it can be seen that the surface is well formed and has few pores. The optical microscope surface picture of Comparative Example 1 is as follows Figure 4 As shown, it can be seen that the surface molding is good, but there are a few defects. For Example 1 and Example 2, the electron microscope EDS surface scanning analysis of Example 1 shows that the powder formula and the surface element mass distribution of the molded sample are roughly the same, as shown in the following figure. Figure 5 The mechanical properties of Example 1 and Example 2 were tested for Comparative Example 1. The hardness is shown in Table 2. The tensile test data is shown in Table 3. The friction coefficient of friction and wear is shown in Table 4. Figure 6 XRD phase analysis was performed on Example 1 and Example 2, and the specific data are as follows: Figure 7 As shown in the figure, the diffraction peak of CuTi2 appears after adding Cu. It is precisely because of the presence of CuTi2 that the hardness, tensile strength, yield strength and wear resistance of the sample are significantly improved.

[0042] Table 2 Hardness table of alloy samples . Table 3 Tensile data of alloy samples. The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A TC4-Cu alloy powder, characterized in that: The TC4-Cu alloy powder is calculated based on 100% by mass: 3-5wt% Cu powder and the remainder is TC4 powder.

2. The TC4-Cu alloy powder according to claim 1, characterized in that: The Cu powder and TC4 powder are solid spherical powders with a powder particle size of 15-53 μm.

3. A selective laser melting method for TC4-Cu alloy powder, characterized in that: The steps include: (1) Put Ti powder, Al powder, V powder and Cu powder into a ball mill and mix them evenly using a ball mill; (2) placing the mixed powder obtained in step (1) into a drying oven for drying; (3) vibrating and sieving the powder obtained in step (2); (4) The powder obtained in step (3) is placed in a metal additive manufacturing device for molding.

4. The method according to claim 3, characterized in that: In step (2), argon gas is introduced into the ball mill as a protective gas, the rotation speed of the ball mill is 200 r / min, the ball-to-material ratio is 3:1, and the ball milling time is 3 h.

5. The method according to claim 3, characterized in that: In step (2), the drying box is evacuated before drying, the drying temperature is 80° C., and the drying time is 8 hours.

6. The method according to claim 3, characterized in that: The mesh size of the sieve used for vibration screening in step (3) is 200 mesh, the vibration time is 10 minutes, the vibration frequency is 50 Hz, and the amplitude is 1 mm.

7. The method according to claim 3, characterized in that: The specific process parameters of the molding in step (4) are: scanning speed of 950-1550 mm / s, laser power of 130-250 W, powder thickness of 30 μm, scanning spacing of 100 μm, adjacent powder layer scanning angles rotated by 67°, TC4 substrate selected as the molding substrate, substrate preheating temperature of 200°C, argon as the protective gas in the molding chamber, and oxygen concentration in the molding chamber less than 100 ppm.

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