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Article

Microstructure and Properties of Ti6Al4V Surface Processed by Continuous Wave Laser in Different Atmospheres

by
Lei Huang
1,
Lei Li
2,*,
Yanfei Zhao
1,
Yaoyao Liu
1,
Hongyu Zheng
2,*,
Zhongchen Du
3 and
Jian Liu
3
1
National Key Laboratory of Marine Corrosion and Protection, Luoyang Ship Material Research Institute, Luoyang 471000, China
2
Center of Advanced Laser Manufacturing (CALM), School of Mechanical Engineering, Shandong University of Technology, Zibo 255000, China
3
Himile Mechanical Manufacturing (Shandong) Co., Ltd., Weifang 261500, China
*
Authors to whom correspondence should be addressed.
Coatings 2024, 14(6), 753; https://doi.org/10.3390/coatings14060753
Submission received: 7 May 2024 / Revised: 12 June 2024 / Accepted: 13 June 2024 / Published: 14 June 2024
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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Abstract

:
Titanium alloys are considered lightweight alloys and are widely applied across various industries. However, titanium alloys are prone to wearing out or galvanic corrosion. In this paper, Ti6Al4V alloy was scanned by using a continuous laser in different atmospheres to prepare composite hardening coatings. The scanning speed was varied to adjust the heat input. When the alloy was irradiated in air, a whole coating composed of TiO2 and TiN was fabricated. With the increase in scanning speed from 10 mm/s to 20 mm/s, the melting area of the surface decreased from about 1.8 mm to 0 mm, but the thickness of the coatings underwent no significant change. When prepared under compressed oxygen with a speed of 10 mm/s, a coating with a thickness of about 60 μm was prepared. In addition, the layered phenomenon occurred, and an N-enriched layer was formed at the bottom of the coating. The coatings were composed of TiO2, TiN and Ti. With the increase in the scanning speed, the thickness of the coatings decreased obviously. The testing results show that the hardness of samples Ti-A10 and Ti-O10 increased by around 160% and 140% over that of untreated samples, respectively. The anti-corrosion performance of the samples treated via laser scanning was also improved.

1. Introduction

The Ti6Al4V alloy is a dual-phase titanium alloy, and it is widely used in marine, aerospace and biomedical industries due to its excellent properties, including high strength-to-weight ratio, nonmagnetic, non-toxic, good plasticity and bio-compatibility [1,2,3]. However, the hardness of Ti6Al4V is not high enough to avoid adhesive wear and abrasive wear during the grinding process [4]. In marine environments, titanium alloys are prone to coming into contact with materials with high corrosion potential such as steel and copper, leading to galvanic corrosion and serious damage [5,6]. When used as bio-implant materials, alloying elements of Ti6Al4V are released into the human body slowly, causing local inflammation, neurological disorders, etc. [7,8]. Therefore, the surface hardening or preparation of a coating layer is necessary to overcome these problems.
The surface modifications of titanium and its alloys have been carried out in maffle furnaces by many researchers. S. Kumar et al. [9] treated Ti6Al4V via thermal oxidation at 500, 650 and 800 °C for different hours in air. The results showed a threefold increase in the hardness obtained for the alloy oxidized at 650 °C for 48 h compared to that of the untreated one. A. Shankar et al. [10] have also reported that both corrosion resistance and hardness of thermal oxidized pure titanium were improved greatly compared with untreated titanium. Z. Wang et al. [11] treated Ti-15Mo at 1173 K in air for 1–4 h to obtain samples with different endosmic oxygen depths. Due to the oxygen content gradient, these samples exhibited an optimal balance of strength and elongation. The hybrid oxide coatings for medical applications have also been prepared using a two-step procedure, comprising thermal oxidation and subsequent electrochemical oxidation [12]. The produced coatings showed high corrosion resistance and were not cytotoxic. However, it would take a long time to treat these alloys via thermal oxidation in furnaces. In the meantime, the performance might decrease due to the overall heating. The creation of different compound layers on the Ti6Al4V surface initiated by the use of a laser, e.g., titanium oxides [13,14,15] and titanium nitrides [16] in different gas atmospheres is an effective method. Titanium oxides or titanium nitrides on the surface can lead to surface hardening and improve wear resistance [17,18]. These titanium compounds are non-conductive. As a result, the galvanic corrosion in the marine environment could be inhibited [5,19]. Furthermore, the chemical compound layers can keep the implants separate from the body fluid and tissues. And then it is difficult for the toxic alloy elements to diffuse into the human body [20]. As a result, the biocompatibility and bioactivity of titanium implants are improved [21].
Many studies on the laser surface processing of titanium alloys have been carried out. The local morphological changes of titanium surface induced by a nanosecond TEA CO2 laser under different gas atmospheres were investigated by Ciganovic et al. [22]. The results showed that the roughness of the irradiated area increased in all cases, while the surface features obtained in air and oxygen were smooth, dome-like structures. The dynamic reaction processes between pure titanium and air under continuous-mode laser heating was also investigated by the use of a synchrotron X-ray diffraction test [23]. Titanium nitrides appear first, while TiO2 is observed during the cooling period, resulting from the solidification of the liquid titanium oxides. However, the microstructures and physiochemical properties of the coating layer fabricated by using a continuous-mode laser under different gas atmospheres have not been sufficiently examined according to our knowledge.
In the present paper, a continuous-mode laser with a wavelength of 1080 nm was used to irradiate Ti6Al4V in air or pure oxygen, which aimed to prepare protective coatings on the surface. The microstructures and phase compositions of the coatings were investigated via SEM and XRD, respectively. The effects of the atmosphere and scanning speed were studied to highlight the effectiveness of the laser in preparing coatings on the surface. In addition, the physiochemical properties of the coating layers processed under different gas atmospheres, including hardness and corrosion resistance, were tested.

2. Materials and Methods

2.1. Materials and Sample Preparation

Commercial Ti6Al4V plates (80 × 40 × 3 mm3) were used as the substrate material. The chemical composition is shown in Table 1. Before the laser processing, the alloy plates were mechanically polished using varying grades of SiC paper (400, 600, 800), rinsed in deionized water and dried using a stream of compressed air.
The laser treatments were performed using a continuous-mode fiber laser with a 1080 nm wavelength. The laser spot with a diameter of about 4 mm and a Gaussian energy distribution was moved over the substrate surface to form an oxidation region. The laser power was fixed at 500 W. The scanning speed ranged from 10 mm/s to 20 mm/s. The processing atmosphere included two kinds: air and compressed oxygen. The compressed oxygen was supplied coaxially, and the gas pressure was maintained at 0.2 MPa. The parameters of the laser processing are summarized in Table 2.

2.2. Characterization of the Microstructure and Phase Composition

The surface morphologies of the Ti6Al4V substrates processed by using a laser were observed using an industrial camera equipped with a 32-megapixel CCD (charge-coupled device) sensor. The frame rate could reach 60 frames per second. The zoom lens of the camera had a variable magnification from 0.75 to 4.5. The cross sections of the substrates were exposed via wire electric discharge machining. Upon mounting with acrylic resin, the samples were ground successively with SiC grinding papers (400, 600, 800, 1000 grit), polished with a polycrystalline diamond suspension (2.5 μm) and ultrasonically rinsed in ethanol for 10 min. Subsequently, the polished samples were etched with the Kroll’s Reagent for 15 s, then cleaned using deionized water to wash off the etching solution. The cross-sectional microstructures were examined via scanning electron microscopy (SEM, FEI Quanta 250, Thermo Scientific, Waltham, MA, USA) equipped with energy dispersive spectroscopy (EDS). The typical regions with different metallographic structures in the cross sections were selected for EDS testing. The phase composition of the oxidization layers was analyzed via X-ray diffraction (XRD, Bruker D8 Advance, Billerica, MA, USA).

2.3. Hardness and Corrosion Test

After the laser processing, Vickers microhardness measurements with a load of 19.61 N for 15 s were performed on the surface of the Ti6Al4V substrate to evaluate the surface hardening. The tester was 200HVS-5 provided by Huayin company (Weinan, China). Five measurements were averaged for each sample.
The corrosion properties of the untreated and laser-treated samples were evaluated by means of potentiodynamic polarization curves. The electrolyte solution was prepared using the salt solution (0.62 M NaCl solution). The electrochemical experiments were carried out using an electrochemical measurement system (IVIUM Vertex. One, Eindhoven, The Netherlands). The corrosion cell, which contained 50 mL of electrolyte, was combined with a typical three-electrode configuration. The silver chloride electrode (SCE, R0302) was employed as the reference electrode and the counter electrode (CE) was a platinum plate with an area of 1 cm2. The samples were used as the working electrode (WE). The sample for the corrosion test was scanned once by the laser, and the scanning line for the test was 1 cm in length. Potentiodynamic polarization tests were carried out at a scan rate of 10 mV/s from −2 V to +1 V vs. SCE with respect to the open circuit potential (OCP). The corrosion potential and corrosion current density were determined from the polarization curves using the Tafel extrapolation method.

3. Results and Discussion

3.1. The Microstructures and Phase Compositions of Samples Processed in Air

The Ti6Al4V alloy was treated via laser scanning in air to prepare titanium oxide coatings. The surface morphology of the titanium alloy prepared under three parameters is shown in Figure 1. When the scanning rate was 10 mm/s, the heat input was high, melting occurred on the surface of the titanium alloy, and ripple-shaped structures were caused after solidification. The laser energy along the radius direction in the spot had a Gaussian distribution, and the energy density was the highest at the center of the spot, so the width of the melting area was less than the spot diameter. When the scanning speed increased to 15 mm/s, the heat input decreased, and the width of the melting zone decreased from 1.8 mm to about 1 mm. When the scanning speed continued to increase to 20 mm/s, the titanium alloy surface did not melt obviously, and the color of the middle area turned gray. The thickness of the oxide film varied in the edge region, which made it exhibit different colors.
The cross-sectional microstructure of the Ti-A10 sample (scanning speed of 10 mm/s under an atmospheric atmosphere, laser power of 500 W) is shown in Figure 2. The phase transformation of the titanium alloy matrix took place under laser heating, and the original elongated grains along the rolling direction transformed into acicular structures [24]. A complete coating with a thickness of approximately 1 μm above the substrate was prepared. The outer side of the coating was relatively dense, and the inner area adjacent to the substrate presented a dendritic shape. The EDS results of the three points in Figure 2 are listed in Table 3. Spot 1 mainly contained elements such as Ti, O and N. Spot 2 was located in the matrix near the coating. Due to diffusion, both O and N elements appeared. The nitrogen and oxygen content reached approximately 6.13 at. % and 5.24 at. %, respectively. As the depth increased, the contents of O and N elements in the three regions changed slightly.
The modified layer on the surface of the titanium alloy was examined by using XRD, and the result is shown in Figure 3. The coating is mainly composed of R-phase TiO2 and a small amount of TiN. This is due to the presence of oxygen and nitrogen in the air, which react with titanium when the laser is heating the surface of the titanium alloy. Although TiO2 is a more stable phase than TiN, synchrotron X-ray radiation studies have shown that due to reaction kinetics, TiN is produced earlier than TiO2 [22]. During the cooling phase, some TiN will transform into TiO2. There was no significant layering phenomenon in this coating. Due to the penetrating effect of X-rays, the diffraction peaks of titanium alloy appear in the diffraction pattern.
The scanning electron microscope pictures of the titanium alloy sample with sample numbers Ti-A15 and Ti-A20 (laser power 500 W in an atmospheric atmosphere, scanning speed of 15 and 20 mm/s) are shown in Figure 4, respectively. The cross-sectional morphologies of the two samples were similar to those of the Ti-A10 samples, and a coating with a thickness of about 1 μm was formed on the titanium substrate. Due to less energy input, the dendrite region below the coating was thinner. The Ti-A20 sample’s surface did not melt, so the coating produced was much straighter. Due to the thermal stress during cooling, fine cracks were generated in the coating. The EDS results of the coatings are similar to those of Ti-A10. Combined with the XRD results, these coatings also consisted of TiO2 and a small amount of TiN.

3.2. The Microstructures and Phase Compositions of the Samples Processed in Compressed Oxygen

When the titanium alloy was treated via laser scanning, the surrounding atmosphere affected the chemical reaction. The microstructures, compositions and properties of the oxide layers would be varied. Therefore, compressed oxygen with a pressure of 0.2 MPa was supplied coaxially during the laser scanning, and the changes of microstructures, compositions and properties of the coatings were analyzed.
The cross-sectional morphologies of the Ti-O10 sample are shown in Figure 5. The bottom part in Figure 5a is a titanium alloy matrix. Due to the thermal effect of the laser, the grains of the matrix were transformed into an acicular structure. The surface coating could be divided into dual obvious layers. The thickness of the coating was about 60 μm. The coating had a dense structure outside and a dendritic structure inside. The microstructure of the box zone is shown in Figure 5b. There is a dense layer under the dendritic shapes. EDS tests were carried out on the coating and nearby titanium substrate, and the results are shown in Table 4. Ti and O were the main elements in the Spot 1 region. The dendritic regions had a similar elemental composition to that of Spot 1. The EDS result of Spot 3 shows that the nitrogen content increased obviously in the internal layer. N and O elements diffused into the Ti6Al4V substrate and therefore appeared in Spot 4.
The XRD pattern of the surface of the Ti-O10 titanium alloy sample is shown in Figure 6. The external coating was mainly composed of rutile, with a small amount of Ti. When the coating was prepared under a compressed oxygen atmosphere, the main phase generated was rutile. The melting point of titanium oxide is around 1800 °C, slightly higher than the melting point of the titanium alloy. During the laser scanning, the melting of titanium and titanium oxide accelerated the reaction between titanium and the surrounding gases. Due to the unsealed atmosphere, nitrogen in the air would also enter the laser scanning area. The free energy of TiO2 generation is lower than that of TiN, resulting in higher stability. Therefore, even if TiN was generated in the molten pool, it would transform into TiO2 during the cooling process. However, the temperature at the bottom of the molten pool was relatively low, and N element could not be completely replaced by oxygen, leaving it inside the coating. Due to the different corrosion resistance, an intermediate layer was formed after metallographic etching.
The cross-sectional morphologies of the Ti-O15 titanium alloy sample are shown in Figure 7. Due to the cooling effect of the compressed oxygen flow, the surface flatness of the titanium alloy did not change obviously. The heated surface shrank during cooling and was restrained by the substrate, resulting in surface tension. Under the action of surface tension, cracks occurred in several areas of the surface [25,26]. When the liquid phase was not enough, some deep ditches were generated on the surface. These ditches were the results of the interaction between the surface tension and liquid phase. Therefore, they were only found in the cross section of sample Ti-O15. The EDS results of the four areas in Figure 7 are shown in Table 5. The main components in Spot 1, located on the outside of the coating, were Ti and O. The nitrogen content in areas 2, 3 and 4 on the internal coating was higher. The phenomenon is the same as that in Ti-O10. The outside of the coating experienced a higher temperature. As a result, titanium nitride could be replaced by oxygen, and an outside coating with a lower N content was formed. Figure 8 shows the surface XRD results for the Ti-O15 sample. The coating consisted of rutile (TiO2) and TiN. Due to the thin surface oxide layer, internal nitrides are shown in the XRD pattern.
The cross-sectional morphologies of the Ti-O20 titanium alloy surface are shown in Figure 9. The surface flatness was also not changed obviously. Due to the rapid cooling, the coating formed on the surface was peeled off, as shown in Figure 9b. In this situation, it is difficult to achieve a good protective effect.

3.3. Hardness and Anti-Corrosion Performance

The surface hardness and corrosion resistance of the Ti-A10 and Ti-O10 samples were tested and compared with Ti6Al4V to evaluate the effects of the laser processing under different atmospheres. Figure 10 shows the Vickers hardness testing results. The average surface hardness of the Ti-A10 sample could reach 1011.9 ± 122.8 HV2, and that of the Ti-O10 sample could reach 926.9 ± 28.1 HV2. Compared to Ti6Al4V, the hardness of each treated sample obviously increased. The post-indentation sites were examined via optical microscopy, and there were no cracks detected from the edges of these sites. The images are attached in the Supplementary Materials. Because the hardness of nitride is slightly higher than that of titanium oxide [27], the surface hardening effect of the titanium alloy prepared in air was slightly better than that of the titanium alloy prepared in an oxidizing atmosphere.
The anti-corrosion performances of the untreated and treated Ti6Al4V were evaluated via polarization measurements (Figure 11). The corrosion potential and corrosion current were extrapolated by using the Tafel method [28], and the results are shown in Table 6. The corrosion potential and corrosion current of the untreated titanium was −0.9101 V and 3.95 × 10−4 A/cm2, whereas the corrosion potential of the Ti-O10 sample positively shifted to −0.5693 V, and the corrosion current decreased to 7.49 × 10−4 A/cm2. When the coatings were prepared under an air atmosphere, the corrosion potential was −0.6908 V, which was more negative than that of Ti-O10. However, the corrosion current of Ti-A10 was the lowest and reached 6.49 × 10−4 A/cm2. Therefore, the corrosion resistance of the titanium treated with the laser under both atmospheres was greatly improved due to the titanium oxides’ and nitrides’ composite coatings.

4. Conclusions

In this study, the Ti6Al4V alloy was irradiated using a continuous laser with a wavelength of 1080 nm in air or compressed oxygen to fabricate anti-corrosion hardening coatings. The laser scanning speed was varied to adjust the heat input. When the alloy was treated in air, a whole coating composed of TiO2 and TiN was prepared on the surface. The thickness of the coatings under different scanning speeds was similar and was approximately 1 μm. However, with the scanning speed decreasing from 20 mm/s to 10 mm/s, the width of the melting area increased from 0 mm to around 1.8 mm. And a rippled surface was formed. When prepared under compressed oxygen with a speed of 10 mm/s, a coating with a thickness of about 60 μm was prepared. When the scanning speed was 10 mm/s, an intermedia layer containing N was formed at the bottom of the coating. The outside of the coating was mainly composed of Ti and O. With the increased scanning speed, the thickness of the coating decreased. Combined with the XRD results, the coating prepared under compressed oxygen consisted of TiO2, TiN and Ti. The testing results show that the hardnesses of samples Ti-A10 and Ti-O10 increased by around 160% and 140% over that of untreated samples, respectively. The anti-corrosion performance of the samples treated via laser scanning was also improved.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/coatings14060753/s1, Figure S1: Optical microscopy images of the post-indentation sites; (a) Ti-A10; (b) Ti-O10.

Author Contributions

Conceptualization, L.H., L.L. and H.Z.; methodology, Y.Z. and L.L.; software, Y.L. and J.L.; validation, Z.D., Y.L. and L.L.; formal analysis, L.H. and L.L.; investigation, Y.Z.; resources, Y.L.; data curation, Z.D.; writing—original draft preparation, L.L.; writing—review and editing, H.Z.; visualization, J.L.; supervision, L.H. and H.Z.; project administration, L.H.; funding acquisition, H.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Natural Science Foundation of Shandong Province, grant number ZR2022ZD07 and Taishan Scholar Project of Shandong Province, grant number tscy202006025.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

Zhongchen Du and Jian Liu are employed by Himile Mechanical Manufacturing (Shandong) Co., Ltd. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

References

  1. Li, G.; Ma, F.; Liu, P.; Qi, P.; Li, W.; Zhang, K.; Chen, X. Review of micro-arc oxidation of titanium alloys: Mechanism, properties and applications. J. Alloys Compd. 2023, 948, 169773. [Google Scholar] [CrossRef]
  2. Liu, H.; Huang, X.; Huang, S.; Qiao, L.; Yan, Y. Anisotropy of wear and tribocorrosion properties of L-PBF Ti6Al4V. J. Mater. Res. Technol. 2023, 25, 2690–2701. [Google Scholar] [CrossRef]
  3. Liu, H.; Wu, L.; Wei, H.; Cai, J.; Luo, K.; Xu, X.; Lu, J. Microstructural evolution and tensile property enhancement of remanufactured Ti6Al4V using hybrid manufacturing of laser directed energy deposition with laser shock peening. Addit. Manuf. 2022, 55, 102877. [Google Scholar] [CrossRef]
  4. Chan, C.W.; Lee, S.; Smith, G.; Sarri, G.; Ng, C.H.; Sharba, A.; Man, H.C. Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen. Appl. Surf. Sci. 2016, 367, 80–90. [Google Scholar] [CrossRef]
  5. Ashrafizadeh, A.; Ashrafizadeh, F. Structural features and corrosion analysis of thermally oxidized titanium. J. Alloys Compd. 2009, 480, 849–852. [Google Scholar] [CrossRef]
  6. Zhao, Y. Low cost technology and application of titanium for marine seawater pipeline in the USA. Dev. Appl. Mater. 2020, 6, 93–97. [Google Scholar]
  7. Wang, H.; Zhang, R.; Yuan, Z.; Shu, X.; Liu, E.; Han, Z. A comparative study of the corrosion performance of titanium (Ti), titanium nitride (TiN), titanium dioxide (TiO2) and nitrogen-doped titanium oxides (N–TiO2), as coatings for biomedical applications. Ceram. Int. 2015, 41, 11844–11851. [Google Scholar] [CrossRef]
  8. Zhao, X.; Zhang, P.; Wang, X.; Chen, Y.; Liu, H.; Chen, L.; Li, W. In-situ formation of textured TiN coatings on biomedical titanium alloy by laser irradiation. J. Mech. Behav. Biomed. 2018, 78, 143–153. [Google Scholar] [CrossRef] [PubMed]
  9. Kumar, S.; Narayanan, T.; Raman, S.; Seshadri, S. Thermal oxidation of Ti6Al4V alloy: Microstructural and electrochemical characterization. Mater. Chem. Phys. 2010, 119, 337–346. [Google Scholar] [CrossRef]
  10. Shankar, A.R.; Karthiselva, N.S.; Mudali, U.K. Thermal oxidation of titanium to improve corrosion resistance in boiling nitric acid medium. Surf. Coat. Technol. 2013, 235, 45–53. [Google Scholar] [CrossRef]
  11. Wang, Z.; Yao, K.; Du, B.; He, S.; Min, X.; Xin, S.; Zheng, S. High strength and high work hardening rate in oxygen gradient Ti-15Mo alloy. J. Mater. Sci. Technol. 2024, 198, 56–62. [Google Scholar] [CrossRef]
  12. Ossowska, A.; Olive, J.; Zielinski, A.; Wojtowicz, A. Effect of double thermal and electrochemical oxidation on titanium alloys for medical applications. Appl. Surf. Sci. 2021, 563, 150340. [Google Scholar] [CrossRef]
  13. Lavisse, L.; Sahour, M.C.; Jouvard, J.M.; Pillon, G.; de Lucas, M.M.; Bourgeois, S.; Grevey, D. Growth of titanium oxynitride layers by short pulsed Nd:YAG laser treatment of Ti plates: Influence of the cumulated laser fluence. Appl. Surf. Sci. 2009, 255, 5515–5518. [Google Scholar] [CrossRef]
  14. Skowronski, L.; Antończak, A.J.; Trzcinski, M.; Hiller, T.; Bukaluk, A.; Wronkowska, A.A. Optical properties of laser induced oxynitride films on titanium. Appl. Surf. Sci. 2014, 304, 107–114. [Google Scholar] [CrossRef]
  15. Yang, C.C.; Lin, Y.C.; Yang, C.C.; Lin, Y.H.; Huang, K.C.; Lin, K.M.; Hsiao, W.T. Laser- induced coloring of titanium alloy using ultraviolet nanosecond pulses scanning technology. J. Alloy Compd. 2017, 715, 349–361. [Google Scholar] [CrossRef]
  16. Dahotre, S.N.; Vora, H.D.; Pavani, K.; Banerjee, R. An integrated experimental and computational approach to laser surface nitriding of Ti-6Al-4V. Appl. Surf. Sci. 2013, 271, 141–148. [Google Scholar] [CrossRef]
  17. Wang, X.; Han, W. Oxygen-gradient titanium with high strength, strain hardening and toughness. Acta Mater. 2023, 246, 118674. [Google Scholar] [CrossRef]
  18. Liu, Z.; Ren, S.; Li, T.; Chen, P. A Comparison Study on the Microstructure, Mechanical Features, and Tribological Characteristics of TiN Coatings on Ti6Al4V Using Different Deposition Techniques. Coatings 2024, 14, 156. [Google Scholar] [CrossRef]
  19. Somsanith, N.; Narayanan, S.; Kim, Y.; Park, S.; Bae, T.; Lee, M. Surface medication of Ti-15Mo alloy by thermal oxidation: Evaluation of surface characteristics and corrosion resistance in Ringer’s solution. Appl. Surf. Sci. 2015, 356, 1117–1126. [Google Scholar] [CrossRef]
  20. Wang, S.; Liu, Y.; Zhang, C.; Liao, Z.; Liu, W. The improvement of wettability, biotribological behavior and corrosion resistance of titanium alloy pretreated by thermal oxidation. Tribol. Int. 2014, 79, 174–182. [Google Scholar] [CrossRef]
  21. Alontseva, D.; Safarova, Y.; Voinarovych, S. Biocompatibility and corrosion of microplasma-sprayed titanium and tantalum coatings versus titanium alloy. Coatings 2024, 14, 206. [Google Scholar] [CrossRef]
  22. Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D.; Bokorov, M.; Trtica, M. Surface modification of the titanium implant using TEA CO2 laser pulses in controllable gas atmospheres—Comparative study. Appl. Surf. Sci. 2012, 258, 2741–2748. [Google Scholar] [CrossRef]
  23. Zeng, C.; Wen, H.; Zhang, B.; Sprunger, P.T.; Guo, S.M. Diffusion of oxygen and nitrogen into titanium under laser irradiation in air. Appl. Surf. Sci. 2020, 505, 144578. [Google Scholar] [CrossRef]
  24. Kumar, C.; Das, M.; Paul, C.P.; Bindra, K.S. Comparison of bead shape, microstructure and mechanical properties of fiber laser beam welding of 2 mm thick plates of Ti-6Al-4V alloy. Opt. Laser Technol. 2018, 105, 306–321. [Google Scholar] [CrossRef]
  25. Nguyen, H.; Pramanik, A.; Basak, A.; Dong, Y.; Parkash, C.; Debnath, S.; Shankar, S.; Jawahir, I.; Dixit, S.; Buddhi, D. A critical review on additive manufacturing of Ti-6Al-4V alloy: Microstructure and mechanical properties. J. Mater. Res. Technol. 2022, 18, 4641–4661. [Google Scholar] [CrossRef]
  26. Suyitno; Pujiyulianto, E.; Arifviato, B.; Mahardika, M.; Salim, U. Evaluation of quantitative hot cracking criteria. Mater. Sci. Technol. 2022, 38, 269–280. [Google Scholar] [CrossRef]
  27. Jambagi, S.; Malik, V. A review on surface engineering perspective of metallic implants for orthopaedic applications. J. Miner. Metals Mater. Soc. 2021, 73, 4349–4364. [Google Scholar] [CrossRef]
  28. Hou, Y.; Peng, Z.; Liang, J.; Liu, M. Ni-Al nanocomposite coating electrodeposited from deep eutectic solvent. Surf. Coat. Technol. 2021, 405, 126587. [Google Scholar] [CrossRef]
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Figure 1. Macroscopic morphology of titanium alloy surface after laser scanning with different parameters in atmospheric atmosphere: (a) The surface morphology of Ti-A10 sample; (b) The surface morphology of Ti-A15 sample; (c) The surface morphology of Ti-A20 sample.
Figure 1. Macroscopic morphology of titanium alloy surface after laser scanning with different parameters in atmospheric atmosphere: (a) The surface morphology of Ti-A10 sample; (b) The surface morphology of Ti-A15 sample; (c) The surface morphology of Ti-A20 sample.
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Figure 2. SEM photographs of Ti-A10 sample: (a) Cross section of the sample; (b) The enlarged view of the corresponding area in (a).
Figure 2. SEM photographs of Ti-A10 sample: (a) Cross section of the sample; (b) The enlarged view of the corresponding area in (a).
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Figure 3. XRD pattern of the surface in sample Ti-A10.
Figure 3. XRD pattern of the surface in sample Ti-A10.
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Figure 4. SEM photos of Ti-A15 and Ti-A20 titanium alloy samples: (a) Cross section of Ti-A15 sample; (b) Close-up view of the rectangle area in Ti-A15 sample; (c) Cross section of Ti-A20 sample; (d) Close-up view of the rectangle area in Ti-A20 sample.
Figure 4. SEM photos of Ti-A15 and Ti-A20 titanium alloy samples: (a) Cross section of Ti-A15 sample; (b) Close-up view of the rectangle area in Ti-A15 sample; (c) Cross section of Ti-A20 sample; (d) Close-up view of the rectangle area in Ti-A20 sample.
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Figure 5. SEM micro morphologies of sample Ti-O10: (a) Cross-sectional morphology of the coating; (b) The enlarged view of the corresponding zone.
Figure 5. SEM micro morphologies of sample Ti-O10: (a) Cross-sectional morphology of the coating; (b) The enlarged view of the corresponding zone.
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Figure 6. XRD pattern of the surface in sample Ti-O10.
Figure 6. XRD pattern of the surface in sample Ti-O10.
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Figure 7. SEM micro morphologies of sample Ti-O15: (a) Cross-sectional morphology of the coating; (b) The enlarged view of the corresponding square area.
Figure 7. SEM micro morphologies of sample Ti-O15: (a) Cross-sectional morphology of the coating; (b) The enlarged view of the corresponding square area.
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Coatings 14 00753 g008
Figure 8. The XRD pattern of the surface in sample Ti-O15.
Figure 8. The XRD pattern of the surface in sample Ti-O15.
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Coatings 14 00753 g009
Figure 9. SEM micro morphologies of sample Ti-O20: (a) Cross-sectional morphology of the coating; (b) The enlarged view of the corresponding rectangular area.
Figure 9. SEM micro morphologies of sample Ti-O20: (a) Cross-sectional morphology of the coating; (b) The enlarged view of the corresponding rectangular area.
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Coatings 14 00753 g010
Figure 10. Vickers hardness of the corresponding samples.
Figure 10. Vickers hardness of the corresponding samples.
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Coatings 14 00753 g011
Figure 11. Potentiodynamic polarization curves of the corresponding samples. The corrosion liquid was 0.62 M NaCl aqueous solution.
Figure 11. Potentiodynamic polarization curves of the corresponding samples. The corrosion liquid was 0.62 M NaCl aqueous solution.
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Table 1. Chemical compositions of the Ti6Al4V substrate (in weight%).
Table 1. Chemical compositions of the Ti6Al4V substrate (in weight%).
ElementTiAlVFeOCNH
wt.%Bal.5.5–6.83.5–4.5<0.3<0.2<0.1<0.05<0.015
Table 2. Laser processing parameters of different samples.
Table 2. Laser processing parameters of different samples.
Sample No.AtmosphereScanning Speed (mm/s)Laser Power (W)
Ti-A10Air10500
Ti-A15Air15500
Ti-A20Air20500
Ti-O10O210500
Ti-O15O215500
Ti-O20O220500
Table 3. EDS results of the corresponding points in Figure 2.
Table 3. EDS results of the corresponding points in Figure 2.
Ti (at. %)O (at. %)N (at. %)Al (at. %)V (at. %)
Spot 150.3131.9714.542.960.22
Spot 278.986.135.246.423.23
Spot 380.266.394.215.783.36
Table 4. EDS results of the corresponding points in Figure 5.
Table 4. EDS results of the corresponding points in Figure 5.
N (at. %)O (at. %)Al (at. %)Ti (at. %)V (at. %)
Spot 10.0232.342.6265.03-
Spot 20.4224.322.5270.412.33
Spot 31.5915.479.6769.293.97
Spot 43.5110.508.7073.114.18
Table 5. EDS results of the corresponding points in Figure 7.
Table 5. EDS results of the corresponding points in Figure 7.
Ti (at. %)O (at. %)Al (at. %)N (at. %)V (at. %)
Spot 162.8732.348.940.163.85
Spot 271.4813.868.521.874.26
Spot 370.8514.958.332.093.79
Spot 473.8612.118.301.044.69
Table 6. Corrosion potential and corrosion current of the corresponding samples.
Table 6. Corrosion potential and corrosion current of the corresponding samples.
Sample No.Ecorr (V)icorr (A/cm2)
Ti−0.91013.95 × 10−4
Ti-O10−0.56937.49 × 10−7
Ti-A10−0.69086.49 × 10−7
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MDPI and ACS Style

Huang, L.; Li, L.; Zhao, Y.; Liu, Y.; Zheng, H.; Du, Z.; Liu, J. Microstructure and Properties of Ti6Al4V Surface Processed by Continuous Wave Laser in Different Atmospheres. Coatings 2024, 14, 753. https://doi.org/10.3390/coatings14060753

AMA Style

Huang L, Li L, Zhao Y, Liu Y, Zheng H, Du Z, Liu J. Microstructure and Properties of Ti6Al4V Surface Processed by Continuous Wave Laser in Different Atmospheres. Coatings. 2024; 14(6):753. https://doi.org/10.3390/coatings14060753

Chicago/Turabian Style

Huang, Lei, Lei Li, Yanfei Zhao, Yaoyao Liu, Hongyu Zheng, Zhongchen Du, and Jian Liu. 2024. "Microstructure and Properties of Ti6Al4V Surface Processed by Continuous Wave Laser in Different Atmospheres" Coatings 14, no. 6: 753. https://doi.org/10.3390/coatings14060753

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