High-surface-quality alloy for 3C products and preparation method and application of high-surface-quality alloy

Abstract

The invention belongs to the technical field of titanium alloys, and particularly relates to a high-surface-quality alloy for 3C products and a preparation method and application of the high-surface-quality alloy. According to the method, TiH2 serves as the raw material, alloy elements Co, Fe or Cu, especially cobalt (Co) are introduced into a TC4 alloy system, the surface quality of the TC4 alloy system can be remarkably improved, the method is suitable for the field of 3C products with the strict requirement for surface integrity, and a new technical path is provided for preparation of high-surface-quality titanium alloy components in the 3C field.

Description

Technical Field

[0001] This application belongs to the field of titanium alloy technology, and more specifically, relates to a high surface quality alloy for 3C products, its preparation method and application. Background Technology

[0002] In the 3C product sector (computers, communications, and consumer electronics), the surface quality of internal structural components and external parts is a key factor determining product grade, reliability, and user experience. Currently, aluminum alloys are the primary metal material used in 3C products. Leveraging mature die-casting, extrusion, and CNC machining technologies, as well as cost advantages, aluminum alloys hold a dominant position in areas such as mobile phone frames and laptop casings. Aluminum alloys typically undergo surface treatment processes such as anodizing to achieve a decorative appearance and improve their wear and corrosion resistance.

[0003] As consumers increasingly demand lightweight, high-strength, and uniquely textured products, titanium alloys (especially TC4 titanium alloy) are gradually emerging as a promising new material. Their superior specific strength, excellent corrosion resistance, and good biocompatibility make them ideal for applications with stringent requirements for structural strength and weight, such as hinges in foldable phones, high-end smartwatch cases, and key structural components in ultra-thin laptops. Some leading consumer electronics brands have already begun experimenting with titanium alloy components in their flagship products to highlight their high-end positioning.

[0004] Furthermore, titanium alloys demonstrate enormous application potential in the 3C (computer, communication, and consumer electronics) field, primarily due to their high specific strength, lightweight nature, and excellent corrosion resistance. These properties can significantly improve the structural strength and durability of consumer electronics products such as smartphones and smartwatches, and support the development of thinner and lighter products. However, 3C products have extremely stringent requirements for their exterior components; the surface must be smooth and flat, without any obvious dents, scratches, cracks, or deformation. In summary, there is an urgent need for titanium alloys in the current 3C product sector, but existing technologies have significant shortcomings in their processing and manufacturing, particularly in consistently achieving high surface quality. Therefore, developing a new method or material system that can specifically improve the surface quality of titanium alloys (such as TC4) is of crucial value for promoting the large-scale application of titanium alloys in high-end 3C products. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a high surface quality titanium alloy, its preparation method and application, aiming to solve the technical problem that it is difficult to obtain high surface quality titanium alloys for current 3C products.

[0006] To achieve the above objectives, in a first aspect, this application provides a method for preparing a titanium alloy with high surface quality, comprising the following steps: (1) TiH2 powder and Al-V master alloy powder are mixed according to the standard composition ratio of TC4 alloy, and 0.5-5wt% of alloy element powder is added to obtain mixed powder; the alloy element powder is Co, Fe or Cu powder; (2) The mixed powder is pressed to obtain a green body; (3) The pressed green blank is vacuum sintered to remove hydrogen, and a high surface quality titanium alloy with doped alloying elements is obtained.

[0007] According to another aspect of the present invention, a high surface quality titanium alloy prepared by the preparation method described above is provided.

[0008] According to another aspect of the present invention, an application of the high surface quality titanium alloy described herein is provided in 3C products.

[0009] According to another aspect of the invention, a 3C product is provided in which internal structural components or external components comprise the aforementioned high surface quality titanium alloy.

[0010] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: (1) This invention provides a method for preparing high surface quality titanium alloys for 3C products. Using TiH2 as raw material, alloying elements Co, Fe or Cu, especially cobalt (Co), are introduced into the TC4 alloy system, which can significantly improve its surface quality. It is suitable for the 3C product field where surface integrity requirements are strict, and provides a new technical path for the preparation of high surface quality titanium alloy components in the 3C field.

[0011] (2) Adding Co to titanium alloy TC4 improves the tensile strength and yield strength of the alloy, which prevents the titanium alloy from deforming due to external force during actual use, and the increased hardness prevents scratches from friction. Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating the preparation process of the high surface quality titanium alloy for 3C products described in this application. Figure 2 The surface quality of TC4 alloy after polishing with different alloying elements in the embodiments of this application; Figure 3 This is a statistical distribution diagram of the equivalent area and number of pores on the surface of TC4 alloy after polishing with different alloying elements according to the embodiments of this application; Figure 4 This is a statistical diagram of the surface porosity of TC4 alloy after polishing with different alloying elements according to the embodiments of this application; Figure 5These are SEM images of the pore morphology and distribution of the TC4 alloy surface after different amounts of Co were doped in Examples 1 to 5. Figure 6 These are SEM images of the TC4 alloy of Example 1, the Ti6Al4V4CoH synthesized in Comparative Example 1, the Ti48Al4Co alloy synthesized in Comparative Example 2, and the Ti6Al4V4Co alloy synthesized in Example 1 after polishing. Figure 7 These are the tensile stress-strain curves of TC4 alloy with different amounts of Co added in Examples 1 to 5. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0014] This invention provides a method for preparing a high-surface-quality titanium alloy, such as... Figure 1 As shown, it includes the following steps: (1) TiH2 powder and Al-V master alloy powder are mixed according to the standard composition ratio of TC4 alloy, and 0.5-5wt% of alloy element powder is added to obtain mixed powder; the alloy element powder is Co, Fe or Cu powder; (2) The mixed powder is pressed to obtain a green body; (3) The pressed green blank is vacuum sintered to remove hydrogen, and a high surface quality titanium alloy with doped alloying elements is obtained.

[0015] In some embodiments, TiH2 powder and Al-V master alloy powder are mixed according to the standard composition ratio of TC4 alloy, and 0.5-5 wt% of alloy element powder is added before being mixed evenly in a powder mixer to obtain mixed powder.

[0016] In a preferred embodiment, the particle size of the TiH2 powder, Al-V master alloy powder, and alloy element powder is less than or equal to 75 μm.

[0017] In some embodiments, step (2) involves pressing the mixed powder using cold isostatic pressing at a pressure of 250-300 MPa for a holding time of 1000-1500 s.

[0018] In some embodiments, step (3) involves placing the pressed green body in a vacuum sintering furnace, evacuating it to 1.0E-3Pa to 1.0E-5Pa, heating it to 600-800°C and holding it for 2-4 hours, and then heating it to 1200-1300°C and holding it for 2-4 hours to perform vacuum sintering and dehydrogenation.

[0019] Preferably, the alloying element powder is Co powder, and the amount mixed in (or doped) is 4-5 wt%.

[0020] This invention proposes to use the high surface quality titanium alloy prepared by the above preparation method in 3C products. The internal structural parts or external parts of the 3C products, such as the middle frame, outer frame or back shell of mobile phones, and the outer shell of laptops, are made of the high surface quality titanium alloy described in this invention.

[0021] This study found that using TiH2 as raw material, introducing alloying elements Co, Fe or Cu, especially cobalt (Co), into the TC4 alloy system can significantly improve its surface quality, making it suitable for 3C product fields with stringent requirements for surface integrity.

[0022] This invention introduces alloying elements Co, Fe, or Cu into TC4 alloys, effectively reducing surface defects such as porosity and scratches, resulting in a more uniform and dense surface morphology. The likely reason is that these alloying elements improve surface smoothness by promoting uniform liquid phase distribution and optimizing sintering fluidity during sintering; simultaneously, their solid solution strengthening and grain boundary pinning effects inhibit abnormal grain growth, further reducing surface roughness and the tendency for micro-defects to form. Notably, in the embodiments, replacing Co with cobalt hydride (CoH) or adjusting the base alloy system TC4 alloy to a titanium-aluminum alloy failed to reproduce the aforementioned surface optimization effects, indicating that Co's role in improving surface quality in the TiH2-based TC4 system is unique and irreplaceable. This novel semi-solid sintering process based on the synergistic regulation of TiH2 and Co provides a new technical path for the preparation of high-surface-quality titanium alloy components in the 3C (computer, communication, and consumer electronics) field.

[0023] The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0024] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0025] The process parameters in the following examples, unless otherwise specified, are generally performed under conventional conditions.

[0026] The embodiments of this application are described below with reference to the accompanying drawings.

[0027] Example 1 (1) Prepare TiH2, Al-V intermediate alloy powder and alloy element X powder with a particle size of less than or equal to 75μm. Mix them in a powder mixer according to the mass ratio of Ti:Al:V:X=86:6:4:4. The alloy element X is Zr, Cr, Co, Fe or Cu, or there is no alloy element added, that is, the amount of X added is 0.

[0028] (2) Place the well-mixed powder into a cold isostatic pressing chamber and press it at a pressure of 280 MPa for 1200 s.

[0029] (3) The pressed green blank is placed in a vacuum sintering furnace and vacuumed to 1.0E-3Pa to ensure that the sample will not be oxidized. It is heated to 600℃ and held for 2h to ensure that the H element is completely removed. Then it is heated to 1250℃ and held for 4h before furnace cooling to obtain titanium alloy sintered samples doped with different alloying elements.

[0030] Example 2 The rest is the same as in Example 1, except that X is Co, and Ti:Al:V:Co = 89.5:6:4:0.5.

[0031] Example 3 The rest is the same as in Example 1, except that X is Co, and Ti:Al:V:Co = 89:6:4:1.

[0032] Example 4 The rest is the same as in Example 1, except that X is Co, and Ti:Al:V:Co = 88:6:4:2.

[0033] Example 5 The rest is the same as in Example 1, except that X is Co, and Ti:Al:V:Co = 87:6:4:3.

[0034] Comparative Example 1 The process is the same as in Example 1, except that CoH powder is used instead of Co powder when doping with Co. The method for preparing CoH powder is to place elemental Co powder in a vacuum sintering furnace, evacuate to 1E-4 Pa, heat to 700°C, then introduce hydrogen gas to -60 kPa, hold at this temperature for 2 hours, and then cool to room temperature to obtain CoH powder.

[0035] Comparative Example 2 Everything else is the same as in Example 1, except that the TC4 basic alloy system is replaced with the Ti48Al system (Ti:Al mass ratio = 52:48). That is, step (1) is as follows: Prepare elemental Ti powder with a particle size of less than or equal to 75 μm, Ti50Al intermediate alloy powder and elemental Co powder, and mix them evenly in a powder mixer according to the mass ratio of Ti:Al:Co = 48:48:4.

[0036] Steps (2) and (3) are the same as in Example 1, and Ti48Al4Co is obtained.

[0037] Semi-circular sintered alloy samples doped with different alloying elements, prepared in the examples, were fixed and embedded in resin and polished under the same conditions. Specifically, the sintered alloy samples were sequentially rough-polished on 600-mesh, 1200-mesh, 2000-mesh, 2500-mesh, and 3000-mesh sandpaper, respectively, and then fine-polished using a silica polishing solution. The polished alloy surfaces were then photographed using a high-definition camera. The results are as follows: Figure 2 Contents (a) TC4 alloy without alloying elements, (b) TC4+4Zr alloy doped with Zr, (c) TC4+4Cr alloy doped with Cr, (d) TC4+4Cu alloy doped with Cu, (e) TC4+4Fe alloy doped with Fe, and (f) TC4+4Co alloy doped with Co.

[0038] Surface quality images obtained by high-definition cameras, such as... Figure 2 As shown, the TC4 alloy, TC4+4Zr alloy, and TC4+4Cr alloy samples have rough surfaces covered with visible pits, indicating low surface quality. The surface quality of TC4+4Cu and TC4+4Fe alloys is improved. The TC4+4Co alloy, doped with Co, has the highest surface quality, almost mirror-like. In the 3C product field, the core value of powder metallurgy material surface quality lies in its multi-dimensional improvement of product functionality, reliability, and user experience. TC4 titanium alloy (Ti-6Al-4V) achieves a significant reduction in surface pits by adding Co, improving surface quality and visual appeal. Essentially, it involves refined control of surface morphology, while simultaneously suppressing surface defects, eliminating stress concentration risks, and improving corrosion resistance.

[0039] Microscopic porosity statistics were performed on the above samples. High-resolution scanning electron microscopy (SEM) was used to photograph the surface of each sample, with more than 50 images taken for each sample. The images were imported into ImageJ software, and threshold analysis was used to statistically analyze the size and number of pores. Finally, mathematical analysis was used to obtain the equivalent area, number distribution, and pore density of the pores. The results are as follows: Figure 3 and Figure 4 As shown. From Figure 3As can be seen, the pore size distribution varies in alloy systems doped with different alloying elements. Compared to TC4, the pore size of TC4+Zr is larger, while the pore sizes of TC4+Cr, TC4+Cu, and TC4+Fe are comparable to those of TC4. In contrast, the pore size in the TC4+Co system is significantly reduced and more uniform, with the equivalent pore area concentrated at 0.002 mm². 2 This indicates that adding Co results in better surface quality compared to other alloys. Figure 4 The total number of pores appearing in 50 SEM images for each alloy system was statistically analyzed, and the pore density of the corresponding alloy system was calculated. The results show that compared with the TC4 system, the number of pores in TC4+Zr is increased. Compared with the undoped TC4 alloy and the alloys doped with Zr and Cr, the pore density of the alloy systems doped with Cu, Fe, and Co is significantly reduced, especially with Co doping, which results in the lowest pore density. This is one of the manifestations of improved alloy surface quality.

[0040] Figure 5 The pore morphology and distribution on the surface of the TC4 alloys in Examples 1 to 5, doped with different amounts of Co, were captured by SEM. It can be seen that with the increase of Co doping amount, the pores on the alloy surface show a significant trend of decreasing in number, size, and roundness. Both the number and size of micropores on the alloy sample surface decrease, indicating a gradual improvement in surface quality. Ti6AlV represents a Co doping amount of 0, Ti6Al4V0.5Co represents a Co doping amount of 0.5wt%, and so on.

[0041] Figure 6 The images show SEM images of the TC4 alloy from Example 1, the Ti6Al4V4CoH alloy synthesized in Comparative Example 1, the Ti48Al4Co alloy synthesized in Comparative Example 2, and the Ti6Al4V4Co alloy synthesized in Example 1 after polishing. It can be seen that the shape and size of the micropores inside the different alloy samples are different. A comparison of the micropores of Ti6Al4V (TC4 alloy) and Ti6Al4V4Co (i.e., TC4+4Co alloy) using scanning electron microscopy reveals... Figure 6 As shown in contents (a) and (d), Ti6Al4V has a large number of micropores, most of which are irregular and elongated in shape, while the Co pores in Ti6Al4V containing Co are almost all circular. Furthermore, adding Co to Ti6Al4V in the form of CoH, as shown... Figure 6 Content (b) revealed that compared to the Ti6Al4V alloy, only the number of pores was reduced, without changing the pore shape. Finally, Co was added to the Ti-Al system of titanium alloys, such as... Figure 6Content (c) shows that the micropore size of the sample neither decreased nor became spherical. Based on these results, it can be concluded that Co, when added to Ti6Al4V in the form of elemental Co, can reduce the number of micropores, sphericalize the shape, and improve surface quality. It is speculated that the decomposition temperature and kinetics of CoH may not match the dehydrogenation process of TiH2, leading to the release of excessive hydrogen at the wrong time point, thus exacerbating defects such as porosity and hydrogen residue, resulting in deterioration of surface quality. Replacing TC4 with the Ti48Al4 system, although the same amount of Co was doped, resulted in a Ti48Al4Co alloy with significantly larger internal pores, indicating that TC4 alloy and Co have a synergistic effect on pore distribution and structure during sintering.

[0042] During polishing, irregular pores in the alloy tend to cause stress to concentrate at sharp corners and edges, leading to preferential material removal and potentially enlarging the pores or creating new scratches. In contrast, circular pores, due to their structure, result in a more uniform stress distribution during polishing, effectively reducing localized spalling and promoting a smooth, continuous surface. This makes it easier to achieve a smooth, uniform mirror finish. Therefore, in this embodiment of the invention, doping the TC4 alloy with a small amount of Co significantly improves the alloy's surface quality.

[0043] Figure 7 The tensile stress-strain curves of TC4 alloy with different amounts of Co added in Examples 1 to 5 are shown. The results show that the yield strength and tensile strength of the TC4 alloy system are significantly improved with the increase of Co content. When the Co content reaches 4wt% (TC4+4Co in the figure), the yield strength and tensile strength are the highest, reaching 1071.71 MPa and 1127.84 MPa, respectively.

[0044] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of producing a titanium alloy having a high surface quality, characterized by, The method comprises the following steps: (1) mixing TiH2 powder and Al-V intermediate alloy powder according to the standard component proportion of TC4 alloy, and mixing 0.5-5wt% alloy element powder to obtain mixed powder; the alloy element powder is Co, Fe or Cu powder; (2) pressing the mixed powder to obtain a green body; (3) vacuum sintering and dehydrogenating the green body obtained by pressing to obtain a high surface quality titanium alloy doped with alloy elements.

2. The production method according to claim 1, wherein The TiH2 powder and Al-V intermediate alloy powder are mixed according to the standard component proportion of TC4 alloy, and 0.5-5wt% alloy element powder is mixed and uniformly mixed in a powder mixer to obtain mixed powder.

3. The production method according to claim 1, wherein The particle size of the TiH2 powder, Al-V intermediate alloy powder and alloy element powder is less than or equal to 75μm.

4. The production method according to claim 1, wherein In step (2), the mixed powder is pressed by cold isostatic pressing, the pressure is 250-300MPa, and the pressure holding time is 1000-1500s.

5. The production method according to claim 1, wherein In step (3), the green body obtained by pressing is placed in a vacuum sintering furnace, vacuum is extracted to 1.0E-3Pa to 1.0E-5Pa, heated to 600-800 first, and then heated to 1200-1300℃ for 2-4 hours.

6. The production method according to claim 1, wherein The alloy element powder is Co powder, and the mixing amount is 4-5wt%.

7. The high surface quality titanium alloy prepared by the preparation method of any one of claims 1 to 6.

8. The application of the high surface quality titanium alloy of claim 7 in 3C products.

9. A 3C product, characterized by The internal structural parts or appearance parts contain the high surface quality titanium alloy of claim 7.

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