A method for preparing a nitrided layer in titanium alloy using ion implantation assistance and its application

Abstract

This invention relates to the field of titanium alloy chemical heat treatment technology, specifically to a method for preparing a nitrided layer in titanium alloy using ion implantation-assisted plasma nitriding and its application. First, the titanium alloy is polished. Then, different dosages of Ti-La elements are implanted into the surface of the titanium alloy using ion implantation technology. Finally, the implanted titanium alloy is subjected to plasma nitriding. The purpose of this invention is to pre-introduce vacancies, dislocations, and other crystal defects on the surface of the titanium alloy using high-energy ion implantation technology, increasing the nitrogen diffusion channels during the nitriding process and improving nitriding efficiency. Under the same nitriding conditions, a thicker nitrided layer can be achieved. Simultaneously, the extremely fine nitride nucleation formed on the surface under the catalysis of La results in a denser surface, achieving higher surface hardness under the same conditions. This helps improve the mechanical, tribological, and fatigue properties of titanium alloys, and can be applied in aerospace, biomedical devices, and marine equipment fields.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy chemical heat treatment technology, specifically to a method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloys and its application. Background Technology

[0002] Ti and its alloys possess excellent properties such as low density, high strength, corrosion resistance, and good biocompatibility, making them highly advantageous in the aerospace field and ideal materials for some biomedical devices. However, their surface properties are severely lacking, including low surface hardness, poor wear resistance, and limited oxidation resistance, which greatly restricts their application in harsh working conditions. Traditional plasma nitriding is slow, and on materials with dense passivation films such as stainless steel and titanium alloys, it is difficult to initiate traditional plasma nitriding, requiring a long time to break through the oxide layer.

[0003] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that traditional plasma nitriding is slow and difficult to start on materials with dense passivation films on the surface of stainless steel, titanium alloys and other materials, requiring a long time to break the oxide layer. The invention provides a method for preparing a nitrided layer of titanium alloys by ion implantation-assisted plasma nitriding and its application.

[0005] To achieve the above objectives, this invention discloses a method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloys, comprising the following steps:

[0006] S1, Substrate pretreatment: Polish the surface of the titanium alloy substrate to a mirror finish and clean it thoroughly;

[0007] S2, Ti-La composite element ion implantation: The pretreated titanium alloy material matrix from step S1 is placed into the ion implantation equipment, and a Ti-La target is selected for ion implantation.

[0008] S3, High-temperature plasma nitriding: The titanium alloy substrate after ion implantation in step S2 is placed in a plasma nitriding system for nitriding treatment. Hydrogen or argon gas is introduced to raise the temperature. When the temperature reaches the set value, nitriding source gas NH3 is introduced. The voltage and duty cycle are controlled to perform nitriding and heat preservation. After nitriding, the sample is cooled to room temperature with the furnace and the titanium alloy substrate is taken out.

[0009] In step S2, the proportion of La in the Ti-La target is 1 wt.%.

[0010] In step S2, the dose of La ion implantation is 1×10⁻⁶. 15 ~1×1017 ionms / cm -2 .

[0011] In step S2, the voltage for La ion implantation is 30~50kV.

[0012] In step S3, the nitriding temperature is 650~800℃, and the nitriding holding time is 10~20h.

[0013] In step S3, the nitriding insulation atmosphere is an NH3 atmosphere.

[0014] The present invention also discloses a nitrided layer prepared by the above-described method of preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy.

[0015] This invention also discloses the above-mentioned method for preparing a nitrided layer by plasma nitriding of titanium alloy with ion implantation assistance. In this method, high-energy ion implantation technology is used to pre-place crystal defects such as vacancies and dislocations on the surface of titanium alloy, thereby increasing the nitrogen diffusion channels in the nitriding process and achieving a thicker nitrided layer. At the same time, under the catalysis of La, extremely fine nitride nuclei are formed on the surface, making the surface more dense. Under the same conditions, higher surface hardness can be achieved.

[0016] This invention also discloses the application of the ion implantation-assisted plasma nitriding method for preparing nitrided layers on titanium alloys in the fields of aerospace, biomedical devices, and marine equipment.

[0017] Compared with existing technologies, the advantages of this invention are as follows: This invention introduces crystal defects such as vacancies and dislocations into the surface of titanium alloys using high-energy ion implantation technology, constructing a high-density defect structure. This provides a rapid channel for nitrogen atom diffusion and lowers the diffusion energy barrier, significantly improving the nitrogen diffusion rate and nitriding efficiency during the nitriding process. Under the same nitriding conditions, a thicker nitrided layer can be obtained. Furthermore, the rare earth element La can promote nitride nucleation and refine the nitride microstructure during nitriding, improving the density and stability of the nitride layer. Through the synergistic effect of defect-enhanced diffusion and rare earth-catalyzed nucleation, this invention can significantly improve the surface hardness and wear resistance of titanium alloys, as well as their mechanical properties and service reliability, making them promising for applications in aerospace, biomedical devices, and marine equipment. Attached Figure Description

[0018] Figure 1 The results of the Vickers hardness test on the cross sections of Examples 1, 2, and 3 and Comparative Examples 1 and 2 are shown.

[0019] Figure 2 The results of the Vickers hardness test of the cross sections of Examples 1 and 4 and Comparative Examples 1 and 5 are shown.

[0020] Figure 3 The results of the Vickers hardness test on the cross sections of Examples 5, 6, 7 and Comparative Example 4 are shown.

[0021] Figure 4 The test results are for the nitrided layer thickness OM of the cross sections in Examples 2, 3 and Comparative Example 2;

[0022] Figure 5 The test results are for the nitrided layer thickness OM of the cross sections in Examples 4, 8 and Comparative Example 3;

[0023] Figure 6 The test results are for the cross-sectional nitriding layer thickness OM of Examples 5, 7 and Comparative Example 4;

[0024] Figure 7 The results of nanoindentation tests are for Examples 1 and 2 and Comparative Examples 1 and 2;

[0025] Figure 8 The results of nanoindentation tests are for Examples 1, 4, 5 and Comparative Example 3;

[0026] Figure 9 The results are for nanoindentation tests in Examples 5, 6 and Comparative Example 4.

[0027] Figure 10 The surface scanning electron microscope results for Example 4 and Comparative Example 5 are shown. Detailed Implementation

[0028] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0029] Example 1

[0030] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 800℃ for 10 h, denoted as ION15-T10-N800, the specific preparation method is as follows:

[0031] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0032] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 800℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0033] Example 2

[0034] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 16 ionms / cm -2 La ions + plasma nitriding at 800℃ for 10 h, denoted as ION16-T10-PN800, the specific preparation method is as follows:

[0035] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 16 ionms / cm -2 Conduct the sampling process.

[0036] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 800℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0037] Example 3

[0038] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 17 ionms / cm -2 La ions + plasma nitriding at 800℃ for 10 h, denoted as ION17-T10-PN800, the specific preparation method is as follows:

[0039] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 17 ionms / cm -2 Conduct the sampling process.

[0040] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 800℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0041] Example 4

[0042] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 650℃ for 10 h, denoted as ION15-T10-PN650, the specific preparation method is as follows:

[0043] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0044] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 650℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace, and then removed for relevant characterization tests.

[0045] Example 5

[0046] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 700℃ for 10 h, denoted as ION15-T10-PN700, the specific preparation method is as follows:

[0047] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0048] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 700℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0049] Example 6

[0050] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 700℃ for 15 hours, denoted as ION15-T15-PN700, are prepared using the following specific method:

[0051] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0052] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 700℃ and held for 15 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0053] Example 7

[0054] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 700℃ for 20 hours, denoted as ION15-T20-PN700, are prepared using the following specific method:

[0055] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0056] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 700℃ and held for 20 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0057] Example 8

[0058] This embodiment uses an ion implantation pretreatment with an implantation volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 750℃ for 10 h, denoted as ION15-T10-PN750, the specific preparation method is as follows:

[0059] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0060] Comparative Example 1

[0061] This comparative example involves plasma nitriding at 800℃ for 10 hours, denoted as T10-PN800. The specific preparation method is as follows:

[0062] The surface of the TC4 sample was polished to a mirror finish with sandpaper, cleaned, and then placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 800℃ and held for 10 hours. After the holding time was completed, the sample was cooled to room temperature with the furnace and then removed for relevant characterization tests.

[0063] Comparative Example 2

[0064] This comparative example uses an ion implantation pretreatment implantation volume of 1×10⁻⁶. 14 ionms / cm -2 La ions + plasma nitriding at 800℃ for 10 h, denoted as ION14-T10-PN800, the specific preparation method is as follows:

[0065] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 14 ionms / cm -2 Conduct the sampling process.

[0066] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 800℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0067] Comparative Example 3

[0068] This comparative example uses an ion implantation pretreatment implantation volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 630℃ for 10 h, denoted as ION15-T10-PN630, the specific preparation method is as follows:

[0069] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0070] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 630℃, and the temperature was maintained for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace, and then removed for relevant characterization tests.

[0071] Comparative Example 4

[0072] This comparative example uses an ion implantation pretreatment volume of 1×10⁻⁶. 15 ionms / cm -2 La ions + plasma nitriding at 700℃ for 7 hours, denoted as ION15-T7-PN700, are prepared using the following specific method:

[0073] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0074] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 700℃ and held for 7 hours. After the holding time, the sample was cooled to room temperature along with the furnace, and then removed for relevant characterization tests.

[0075] Comparative Example 5

[0076] This comparative example involved plasma nitriding at 650℃ for 10 hours, denoted as T10-PN650. The specific preparation method is as follows:

[0077] The TC4 surface was polished to a mirror finish with sandpaper, cleaned, and then placed in an ion implanter for ion implantation. The ion implanter was equipped with a Ti-La target, and the voltage was controlled at 30-50 kV, with controlled beam current density, until the implantation dose reached 1 × 10⁻⁶. 15 ionms / cm -2 Conduct the sampling process.

[0078] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 650℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace, and then removed for relevant characterization tests.

[0079] After cleaning following injection, the sample was placed in a plasma nitriding furnace for nitriding treatment. NH3 was introduced as the ambient atmosphere, and the voltage was set. The nitriding temperature was set to 750℃ and held for 10 hours. After the holding time, the sample was cooled to room temperature along with the furnace and then removed for relevant characterization tests.

[0080] The performance of ION15-T10-N800, ION16-T10-PN800, ION17-T10-PN800, ION15-T10-PN650, ION15-T10-PN700, ION15-T15-PN700, ION15-T15-PN700, ION15-T20-PN700, ION15-T10-PN750, T10-PN800, ION14-T10-PN800, ION15-T10-PN630, ION15-T7-PN700, and T10-PN650 prepared in Examples 1, 2, 3, 4, and 5 above was characterized as follows: The microhardness distribution of the infiltrated layer was tested using an HV-1000 microhardness tester, as shown below. Figures 1-3 As shown, Figure 1 The results show the Vickers hardness test results for the cross sections of Examples 1, 2, and 3, and Comparative Examples 1 and 2. The results indicate that within the effective hardened layer, Example 1 (444.65~925.16 HV) achieves a hardness of 444.65~925.16 HV. 0.05 Example 2 (452.7~939.14HV) 0.05 Example 3 (448.35~945.24 HV) 0.05 Comparison ratio 1 (424.65~844.76 HV) 0.05 Comparative Example 2 (414.6~856.5HV) 0.05 It has higher hardness (approximately 20~100 HV). 0.05 This indicates that the dose of rare earth element La ion implantation was 1×10⁻⁶. 15 ~1×10 17 ionms / cm -2 Within the specified range, ion implantation-assisted plasma nitriding of titanium alloys increases the effective hardness of the hardened layer compared to conventional plasma nitriding. Figure 2 The results of the Vickers hardness tests on the cross sections of Examples 1 and 4 and Comparative Examples 1 and 5 show that within the effective hardened layer, Example 1 (444.65~925.16 HV) achieves a hardness of 100 HV. 0.05 Comparison ratio 1 (424.65~844.76 HV) 0.05 Example 4 (436.2~664.76 HV) 0.05 Comparison ratio 5 (426.2~578.2 HV) 0.05 It has higher hardness (approximately 10~87 HV). 0.05 This indicates that within the high-temperature plasma nitriding temperature range of 650~800℃, ion implantation-assisted plasma nitriding of titanium alloys results in a higher hardness of the hardened layer compared to conventional plasma nitriding. Figure 3The results of the Vickers hardness tests on the cross sections of Examples 5, 6, 7 and Comparative Example 4 are shown. The results show that Example 5 (434.5~686.7 HV) 0.05 Example 6 (443.2~719.42 HV) 0.05 Example 7 (439.2~698.1 HV) 0.05 Comparison ratio 4 (414~595.8 HV) 0.05 It has higher hardness (approximately 20~120 HV). 0.05 The results indicate that within the high-temperature plasma nitriding holding time range of 10–20 h, ion implantation-assisted plasma nitriding of titanium alloys produces a harder hardened layer than traditional plasma nitriding. The microhardness results suggest that the implantation of rare-earth element La ions alters the surface phase composition, improving nitriding efficiency and achieving higher surface hardness.

[0081] The thickness of the infiltrated layer was tested using a ZEISS metallographic microscope, such as... Figures 4-6 As shown, Figure 4 The cross-sectional microstructure results for Examples 2, 3, and Comparative Example 2 are shown. (a) shows the infiltrated layer thickness of Example 2 (152.67 μm), (b) shows the infiltrated layer thickness of Example 3 (159.73 μm), and (c) shows the infiltrated layer thickness of Comparative Example 2 (133.36 μm). The results show that Examples 2 and 3 have a thicker infiltrated layer than Comparative Example 2, indicating that the dose of rare earth element La ion implantation is 1×10⁻⁶. 15 ~1×10 17 ionms / cm -2 Within this range, ion implantation-assisted plasma nitriding of titanium alloys is more conducive to the diffusion of nitrogen atoms than traditional plasma nitriding, resulting in a thicker and more uniform nitrided layer. Figure 5 The results show the cross-sectional microstructure of Examples 8, 4 and Comparative Example 3. (a) shows the thickness of the infiltrated layer in Example 8 (66.19 μm), (b) shows the thickness of the infiltrated layer in Example 4 (28.52 μm), and (c) shows the thickness of the infiltrated layer in Comparative Example 3 (23.94 μm). The results show that Examples 8 and 4 have thicker infiltrated layers than Comparative Example 3. The results indicate that in the range of high-temperature plasma nitriding temperature of 650~800℃, ion implantation-assisted plasma nitriding of titanium alloys is more conducive to the diffusion of nitrogen atoms than traditional plasma nitriding, resulting in a thicker and more uniform infiltrated layer. Figure 6The cross-sectional microstructure results for Examples 7, 5, and Comparative Example 4 are shown. (a) shows the thickness of the infiltrated layer in Example 7 (109.83 μm), (b) shows the thickness of the infiltrated layer in Example 5 (93.17 μm), and (c) shows the thickness of the infiltrated layer in Comparative Example 4 (57.66 μm). The results show that Examples 7 and 5 have thicker infiltrated layers than Comparative Example 4. The results indicate that within the range of 10–20 h of high-temperature plasma nitriding diffusion and holding time, ion implantation-assisted plasma nitriding of titanium alloys is more conducive to nitrogen atom diffusion than traditional plasma nitriding, resulting in a thicker and more uniform infiltrated layer. The microstructure results show that ion implantation technology pre-places crystal defects such as pores and dislocations on the surface of titanium alloys, increasing the nitrogen diffusion channels during the nitriding process and achieving a thicker infiltrated layer.

[0082] Nanoindentation testing is used to evaluate the mechanical properties of sample surfaces, such as... Figures 7-9 As shown, Figure 7 The surface hardness results for Examples 1 and 2 and Comparative Examples 1 and 2 show that Example 1 (18.9 ± 0.72 GPa) and Example 2 (20.07 ± 2.49 GPa) have higher surface hardness (approximately 12-14 GPa higher) than Comparative Example 1 (6.24 ± 0.72 GPa) and Comparative Example 2 (7.48 ± 1.17 GPa), indicating that the rare earth element La ion implantation dose is 1 × 10⁻⁶. 15 ~1×10 17 ionms / cm -2 Within the specified range, ion implantation-assisted plasma nitriding of titanium alloys exhibits higher surface hardness than traditional plasma nitriding. Figure 8 The surface hardness results for Examples 1, 4, 5 and Comparative Example 3 show that Examples 1 (18.9045±0.724 GPa), 4 (11.89±0.68 GPa), and 5 (14.86±0.71 GPa) have higher surface hardness (approximately 2~9 GPa higher) than Comparative Example 3 (9.71±0.83 GPa). This indicates that within the high-temperature plasma nitriding temperature range of 650~800℃, ion implantation-assisted plasma nitriding of titanium alloys has higher surface hardness than conventional plasma nitriding. Figure 9 The surface hardness results for Examples 5, 6, and Comparative Example 4 show that Examples 5 (18.86 ± 0.71 GPa) and 6 (19.27 ± 1.62 GPa) have higher surface hardness (approximately 8 GPa higher) than Comparative Example 4 (11.63 ± 1.09 GPa). This indicates that within the range of 10–20 h of high-temperature plasma nitriding diffusion holding time, ion implantation-assisted plasma nitriding of titanium alloys achieves higher surface hardness than conventional plasma nitriding. The nanoindentation results suggest that the higher surface hardness is likely due to the increased nitriding efficiency achieved by rare earth element La ion implantation.

[0083] The surface morphology of the sample was observed using scanning electron microscopy (SEM), such as... Figure 10 As shown, Figure 10 The images show microscopic images of the surface morphology of Example 4 and Comparative Example 5. The results show that, compared with the surface morphology of plasma nitriding without rare earth element La ion implantation (Comparative Example 5), the surface of plasma nitriding with rare earth element La ion implantation (Example 4) shows a large number of nitride micronuclei on the sample surface. The number of surface nitride nuclei is greatly increased, and the size is significantly refined. More and finer nitride nuclei grow uniformly on the surface, making the surface denser and achieving higher surface hardness.

[0084] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy, characterized in that, Includes the following steps: S1, Substrate pretreatment: Polish the surface of the titanium alloy substrate to a mirror finish and clean it thoroughly; S2, Ti-La composite element ion implantation: The pretreated titanium alloy material matrix from step S1 is placed into the ion implantation equipment, and a Ti-La target is selected for ion implantation. S3, High-temperature plasma nitriding: The titanium alloy substrate after ion implantation in step S2 is placed in a plasma nitriding system for nitriding treatment. Hydrogen or argon gas is introduced to raise the temperature. When the temperature reaches the set value, nitriding source gas NH3 is introduced. The voltage and duty cycle are controlled to perform nitriding and heat preservation. After nitriding, the sample is cooled to room temperature with the furnace and the titanium alloy substrate is taken out.

2. The method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy as described in claim 1, characterized in that, In step S2, the proportion of La in the Ti-La target is 1 wt.%.

3. The method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy as described in claim 1, characterized in that, In step S2, the dose of La ion implantation is 1×10⁻⁶. 15 ~1×10 17 ionms / cm -2 .

4. The method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy as described in claim 1, characterized in that, In step S2, during ion implantation, the ion implantation equipment is evacuated to reduce the gas pressure to 1~5×10⁻⁶. -4 Below Pa.

5. The method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy as described in claim 1, characterized in that, In step S2, the voltage for La ion implantation is 30~50kV.

6. The method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy as described in claim 1, characterized in that, In step S3, the nitriding temperature is 650~800℃, and the nitriding holding time is 10~20h.

7. The method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy as described in claim 1, characterized in that, In step S3, the nitriding insulation atmosphere is an NH3 atmosphere.

8. A nitrided layer prepared by the method for preparing a nitrided layer by ion implantation-assisted plasma nitriding of titanium alloy as described in any one of claims 1 to 7.

9. The application of a diffusion layer prepared by the method of preparing a diffusion layer by ion implantation-assisted plasma nitriding of titanium alloy as described in claim 8 in the fields of aerospace, biomedical devices and marine equipment.

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