Surface Modification, Characterization, and Cytotoxicity of Ti-6Al-4V Alloy Enriched by EDM Process
Source abstract
Abstract
This study investigates the surface modification of Ti-6Al-4V alloy through the electrical discharge machining (EDM) process to improve its suitability for orthopedic and dental implant applications. The analysis focused on evaluating the morphological, wettability, roughness, hardness, and biocompatibility properties of the modified surfaces. Samples were subjected to different dielectric fluids and polarities during EDM. Subsequently, optical microscopy, roughness measurements, Vickers microhardness, contact angle tests, and in vitro cytotoxicity assays were performed. The results demonstrated that EDM processing led to the formation of distinct layers on the sample surfaces, with surface roughness increasing under negative polarity by up to ~304% in Ra and 305% in Rz. Additionally, wettability measurements indicated that the modified surfaces presented a lower water contact angle, which suggests enhanced hydrophilicity. Moreover, the modified samples showed a significant increase in Vickers microhardness, with the highest value reaching 1520 HV in the recast layer, indicating improvements in the mechanical properties. According to ISO 10993-5, all treated samples were classified as non-cytotoxic, presenting RGR values above 75%, similar to the untreated Ti-6Al-4V alloy. Therefore, it is concluded that surface modification through the EDM process has the potential to enhance the properties and safety of biomedical implants made with this alloy.
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Research context
OpenAlex topics: Advanced Machining and Optimization Techniques · Metal and Thin Film Mechanics · Surface Treatment and Coatings
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Department of Materials Engineering, Federal Center for Technological Education of Minas Gerais (CEFET-MG), Belo Horizonte 30421-169, MG, Brazil
Department of Bioengineering, George Mason University, Fairfax, VA 22030, USA
Department of Chemical and Biomedical Engineering, University of Wyoming (UW), Laramie, WY 82071, USA
Funding
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)
References (91)
Show source-provided references
1. Electrochemical Corrosion Behavior of Magnesium and Titanium Alloys in Simulated Body Fluid10.1016/j.electacta.2009.07.047 ↗
2. Enhancing Biocompatibility and Corrosion Resistance of Ti-6Al-4V Alloy by Surface Modification Route10.1007/s11666-018-0746-7 ↗
3. Ti4+ to Ti3+ Conversion of TiO2 Uppermost Layer by Low-Temperature Vacuum Annealing: Interest for Titanium Biomedical Applications10.1006/jcis.2002.8623 ↗
4. TiO2 Nanotubes Synthesised on Ti-6Al-4V ELI Exhibits Enhanced Osteogenic Activity: A Potential next-Generation Material to Be Used as Medical Implants10.1080/10667857.2020.1760510 ↗
5. Yaszemski, M.J. (2003). Biomaterials in Orthopedics, CRC Press.10.1201/b14227 ↗
6. Moayedee, Y., Nikzad, L., and Majidian, H. (2024). Exploration into the Microstructural, Mechanical, and Biological Characteristics of the Functionally Graded 3Y-TZP/Ti6Al4V System as a Potential Material for Dental Implants. J. Mech. Behav. Biomed. Mater., 151.10.1016/j.jmbbm.2024.106380 ↗
7. (Sam) Froes, F.H. (2018). Titanium for Medical and Dental Applications—An Introduction. Titanium in Medical and Dental Applications, Elsevier.10.1016/B978-0-12-812456-7.00001-9 ↗
8. Effects of Tool Electrode on EDM Performance of Ti-6Al-4V10.1007/s12633-018-9760-0 ↗
9. Titanium Alloys for Dental Implants: A Review10.3390/prosthesis2020011 ↗
10. Ronoh, K., Mwema, F., Dabees, S., and Sobola, D. (2022). Advances in Sustainable Grinding of Different Types of the Titanium Biomaterials for Medical Applications: A Review. Biomed. Eng. Adv., 4.10.1016/j.bea.2022.100047 ↗
11. Stich, T., Alagboso, F., Křenek, T., Kovářík, T., Alt, V., and Docheva, D. (2022). Implant-bone-interface: Reviewing the Impact of Titanium Surface Modifications on Osteogenic Processes in Vitro and in Vivo. Bioeng. Transl. Med., 7.10.1002/btm2.10239 ↗
12. Osseointegration and More—A Review of Literature10.1016/j.ijd.2012.03.012 ↗
13. Tanfloc/Heparin Polyelectrolyte Multilayers Improve Osteogenic Differentiation of Adipose-Derived Stem Cells on Titania Nanotube Surfaces10.1016/j.carbpol.2020.117079 ↗
14. Ti Based Biomaterials, the Ultimate Choice for Orthopaedic Implants—A Review10.1016/j.pmatsci.2008.06.004 ↗
15. Investigating Wettability and Corrosion Resistance of the Titanium Alloy Surface Engineered by the WEDM Process10.1016/j.mfglet.2023.08.100 ↗
16. Multifunctional Implant Surfaces: Surface Characterization and Bone Response to Acid-etched Ti Implants Surface-modified by Fibrillar Collagen I10.1002/jbm.a.32702 ↗
17. Histologic Evaluation of Early Human Bone Response to Different Implant Surfaces10.1902/jop.2006.050325 ↗
18. The Roles of Ions on Bone Regeneration10.1016/j.drudis.2018.01.049 ↗
19. American Society of Mechanical Engineers (2019). ASME B46.1—Surface Texture (Surface Roughness, Waviness, and Lay), American Society of Mechanical Engineers.
20. The Influence of Micro-Topography on Cellular Response and the Implications for Silicone Implants10.1163/156856295X00698 ↗
21. Titanium-Based Alloys and Composites for Orthopedic Implants Applications: A Comprehensive Review10.1016/j.matdes.2024.112850 ↗
22. Omarov, S., Nauryz, N., Talamona, D., and Perveen, A. (2022). Surface Modification Techniques for Metallic Biomedical Alloys: A Concise Review. Metals, 13.10.3390/met13010082 ↗
23. Electric Discharge Machining of Titanium and Alloys for Biomedical Implant Applications: A Review
24. Enhanced Micro-Electric Discharge Machining-Induced Surface Modification on Biomedical Ti-6Al-4V Alloy10.1115/1.4053110 ↗
25. Critical Review on the Impact of EDM Process on Biomedical Materials10.1080/10426914.2021.1942907 ↗
26. Performance Evaluation of Electric Discharge Machining of Titanium Alloy—A Review10.1186/s44147-022-00118-z ↗
27. Farooq, M.U., Anwar, S., Bhatti, H.A., Kumar, M.S., Ali, M.A., and Ammarullah, M.I. (2023). Electric Discharge Machining of Ti6Al4V ELI in Biomedical Industry: Parametric Analysis of Surface Functionalization and Tribological Characterization. Materials, 16.10.3390/ma16124458 ↗
28. The Effect of Nano and Micro Hydroxyapatite Powder Additives on Surface Integrity in Electrical Discharge Machining of Ti6Al4V Alloy10.1016/j.surfcoat.2022.128708 ↗
29. Electrical Discharge Machining of Titanium Alloy (Ti–6Al–4V)10.1016/j.apsusc.2007.05.031 ↗
30. Research Progress of Metal Biomaterials with Potential Applications as Cardiovascular Stents and Their Surface Treatment Methods to Improve Biocompatibility10.1016/j.heliyon.2024.e25515 ↗
31. Current Advanced Research Development of Electric Discharge Machining (EDM): A Review
32. Powder Mixed-EDM for Potential Biomedical Applications: A Critical Review10.1080/10426914.2020.1779939 ↗
33. A Review on the Performance of the Materials by Surface Modification through EDM
34. Kossymbayev, A., Ali, S., Talamona, D., and Perveen, A. (2024, January 15–17). Powder-Mixed Micro Electrical Discharge Machining-Assisted Surface Modification of Ti-35Nb-7Zr-5Ta Alloy in Biomedical Applications. Proceedings of the 2024 IEEE 6th Eurasia Conference on IoT, Communication and Engineering, Yunlin, Taiwan.10.3390/engproc2025092071 ↗
35. Modification of Ti6Al4V Alloy Surfaces Using Hydroxyapatite-Mixed Electric Discharge-Assisted Centerless Turning for Application of Bone-Anchored Limb Prosthesis Fixtures10.1007/s11665-024-09748-1 ↗
36. Nauryz, N., Omarov, S., Kenessova, A., Pham, T.T., Talamona, D., and Perveen, A. (2023). Powder-Mixed Micro-Electro-Discharge Machining-Induced Surface Modification of Titanium Alloy for Antibacterial Properties. J. Manuf. Mater. Process., 7.10.3390/jmmp7060214 ↗
37. Investigation the Effect of Negative Polarity of Surface Roughness and Metal Removal Rate During EDM Process10.30684/etj.v38i12A.1591 ↗
38. Cytotoxicity of Copper Ions Released from Metal: Variation with the Exposure Period and Concentration Gradients10.1385/BTER:102:1-3:129 ↗
39. The Biocompatibility of Carbon Nanotubes10.1016/j.carbon.2005.10.011 ↗
40. Carbon Biomedical Devices10.1016/0008-6223(77)90324-4 ↗
41. The Application of Research on Powder Mixed EDM in Rough Machining10.1016/S0924-0136(02)00570-8 ↗
42. Zhang, Y., Liu, Y., Shen, Y., Ji, R., Cai, B., Li, H., and Wang, F. (2012, January 5). A Review of the Current Understanding and Technology of Powder Mixed Electrical Discharge Machining (PMEDM). Proceedings of the 2012 IEEE International Conference on Mechatronics and Automation, New York, NY, USA.10.1109/ICMA.2012.6285692 ↗
43. Santos, R. (2013). Nitretação Por EDM Do Aço AISI 4140, Universidade Federal de Uberlândia.
44. Influence of Kerosene and Distilled Water as Dielectrics on the Electric Discharge Machining Characteristics of Ti–6A1–4V10.1016/S0924-0136(98)00340-9 ↗
45. Study on the Effect of Different Electrode Forms on the Surface Modification of Ti–6Al–4V Alloy by near-Dry Electrical Discharge Machining10.1016/j.matchemphys.2023.128801 ↗
46. EDM Machining Effectiveness for Ti–6Al–4V Alloy Using Cu–TiB2 Ceramic Composite Electrode: A Parametric Evaluation10.1016/j.ceramint.2024.03.135 ↗
47. Karmiris-Obratański, P., Papazoglou, E.L., Leszczyńska-Madej, B., Zagórski, K., and Markopoulos, A.P. (2021). A Comprehensive Study on Processing Ti–6Al–4V ELI with High Power EDM. Materials, 14.10.3390/ma14020303 ↗
48. Mughal, M.P., Farooq, M.U., Mumtaz, J., Mia, M., Shareef, M., Javed, M., Jamil, M., and Pruncu, C.I. (2021). Surface Modification for Osseointegration of Ti6Al4V ELI Using Powder Mixed Sinking EDM. J. Mech. Behav. Biomed. Mater., 113.10.1016/j.jmbbm.2020.104145 ↗
49. Oliveira, L.F.B. (2019). Ativação da Superfície da Liga Ti-6Al-4V Através de Eletroerosão, Centro Federal de Educação Tecnológica de Minas Gerais.
50. Rosa, J.B.D. (2018). Enriquecimento Superficial Da Liga Ti-6Al-4V Com Cálcio e Fósforo Pelo Processo de Usinagem Por Descargas Elétricas, CEFET-MG.
51. (2013). ASTM International ASTM F136—Standard Specification for Wrought Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications (Standard No. UNS R56401).
52. (2016). Implants for Surgery—Metallic Materials—Part 3: Wrought Titanium 6-Aluminium 4-Vanadium Alloy (Standard No. ISO 5832-3:2016).
53. A Review—Metastable β Titanium Alloy for Biomedical Applications10.1186/s44147-023-00196-7 ↗
54. Oliveira, L.F.B., Dos Santos, B.A.B., dos Santos, R.F., and de Souza Costa, H. (2020). ATIVAÇÃO DA SUPERFÍCIE DA LIGA TI-6AL-4V ATRAVÉS DO PROCESSO EDM. Rev. Eletrônica Perspect. Ciência Tecnol., 12.10.22407/1984-5693.2020.v12.p.213-227 ↗
55. (1996). Geometrical Product Specifications (GPS)—Surface Texture: Profile Method—Nominal Characteristics of Contact (Stylus) Instruments (Standard No. ISO 3274:1996).
56. (2009). Biological Evaluation of Medical Devices. Part 5: Tests for in Vitro Cytotoxicity (Standard No. ISO 10993-5:2009).
57. Enhancing Biocompatibility of Co-Cr Alloy Implants via Electrical Discharge Process10.1080/10667857.2018.1475144 ↗
58. Nanoporous Biocompatible Layer on Ti–6Al–4V Alloys Enhanced Osteoblast-like Cell Response10.1016/j.jecm.2013.04.002 ↗
59. Analysis of Micro-Cracks on Machined Surfaces in Dry Electrical Discharge Machining10.1016/j.jmapro.2012.05.003 ↗
60. A Gap-Active Electrical Discharge Machining (GA-EDM) to Rectify the Textural Defects of the Processed Surface10.1016/j.jmapro.2021.01.053 ↗
61. Surface Alloying of Miniature Components by Micro-Electrical Discharge Process10.1080/10426914.2017.1364755 ↗
62. Nafi, M.A., and Jahan, M.P. (2022). Functional Surface Generation by EDM—A Review. Micromachines, 14.10.3390/mi14010115 ↗
63. Influences of Tool Electrodes on Machinability of Titanium α-β Alloy with ISO Energy Pulse Generator in EDM Process10.1016/j.aej.2022.07.059 ↗
64. Han, X., Ma, J., Tian, A., Wang, Y., Li, Y., Dong, B., Tong, X., and Ma, X. (2023). Surface Modification Techniques of Titanium and Titanium Alloys for Biomedical Orthopaedics Applications: A Review. Colloids Surf. B Biointerfaces, 227.10.1016/j.colsurfb.2023.113339 ↗
65. Tool Speed and Polarity Effects in Micro-EDM Drilling of 316L Stainless Steel
66. Machinability Assessment of Titanium Grade 2 Alloy Using Deionized Water in EDM10.1016/j.matpr.2020.02.482 ↗
67. Machinability of Titanium Alloy through Electric Discharge Machining10.1080/10426914.2018.1532092 ↗
68. Electric Discharge Machining—A Potential Choice for Surface Modification of Metallic Implants for Orthopedic Applications: A Review10.1177/0954405415579113 ↗
69. The Relationship of Surface Roughness and Cell Response of Chemical Surface Modification of Titanium10.1007/s10856-012-4611-9 ↗
70. Properties and Applications of Calcium Hydroxide in Endodontics and Dental Traumatology10.1111/j.1365-2591.2011.01886.x ↗
71. Modification of Titanium by Ion Implantation of Calcium and/or Phosphorus10.1016/S0257-8972(98)00717-8 ↗
72. Anomalous Influence of Polarity in Sink EDM of Titanium Alloys10.1016/j.cirp.2018.04.069 ↗
73. Effects of Bioceramic Particles in Dielectric of Powder-Mixed Electrical Discharge Machining on Machining and Surface Characteristics of Titanium Alloys10.1016/j.jmatprotec.2017.02.018 ↗
74. Effect of the Electrical Discharge Machining on Ti6Al4V Corrosion Behaviour in Simulated Body Fluid10.1016/j.surfcoat.2023.129830 ↗
75. Performance Evaluation of Surfactant Mixed Dielectric and Process Optimization for Electrical Discharge Machining of Titanium Alloy Ti6Al4V10.1016/j.cirpj.2023.02.007 ↗
76. Evaluation of the Effect of Surface Modification of Ti64 and 316L by Addition of Calcium Phosphate through Electrical Discharge Machining Process10.1016/j.triboint.2023.108245 ↗
77. Xiang, H., Chen, X., Huang, Y., Wu, C., Mou, G., and Zheng, K. (2025). Decomposition Behavior and Strengthening Mechanism of Ti-TiO2 Material in Selective Laser Melting Process. J. Mater. Eng. Perform., 1–16.10.1007/s11665-025-11314-2 ↗
78. Thermal Based Surface Modification Techniques for Enhancing the Corrosion and Wear Resistance of Metallic Implants: A Review10.1016/j.vacuum.2022.111298 ↗
79. The Impact of Contact Angle on the Biocompatibility of Biomaterials10.1097/OPX.0b013e3181da863e ↗
80. Improved Bio-Physical Performance of Hydroxyapatite Coatings Obtained by Electrophoretic Deposition at Dynamic Voltage10.1016/j.ceramint.2014.04.116 ↗
81. A Review on the Wettability of Dental Implant Surfaces II: Biological and Clinical Aspects10.1016/j.actbio.2014.03.032 ↗
82. Effect of Surface Topography and Chemical Composition on Wettability of Calcium Phosphate Coatings Formed on Ti-40Nb Alloy10.4028/www.scientific.net/KEM.683.370 ↗
83. Optimization of Blood and Protein Flow around Superhydrophilic Implant Surfaces by Promoting Contact Hemodynamics10.2186/jpr.JPR_D_22_00225 ↗
84. Shao, H., Ma, M., Wang, Q., Yan, T., Zhao, B., Guo, S., and Tong, S. (2022). Advances in the Superhydrophilicity-Modified Titanium Surfaces with Antibacterial and pro-Osteogenesis Properties: A Review. Front. Bioeng. Biotechnol., 10.10.3389/fbioe.2022.1000401 ↗
85. Validation and Stability Analysis of a Modified Lactate Dehydrogenase (LDH) Test Method to Be Employed for an in Vitro Viable Skin Model10.1016/j.heliyon.2019.e01618 ↗
86. Cytocompatibility of Cu-Bearing Ti6Al4V Alloys Manufactured by Selective Laser Melting10.1016/j.matchar.2017.12.003 ↗
87. Mechanical Properties, Corrosion Behavior and Cytotoxicity of Ti-6Al-4V Alloy Fabricated by Laser Metal Deposition10.1016/j.matchar.2021.111302 ↗
88. Influence of the Roughness of Dental Implants Obtained by Additive Manufacturing on Osteoblastic Adhesion and Proliferation: A Systematic Review10.1016/j.heliyon.2022.e12505 ↗
89. Pandey, C., Rokaya, D., and Bhattarai, B.P. (2022). Contemporary Concepts in Osseointegration of Dental Implants: A Review. Biomed. Res. Int., 2022.10.1155/2022/6170452 ↗
90. Effect of Cryogenic Treatment on Wear Resistance of Ti–6Al–4V Alloy for Biomedical Applications10.1016/j.jmbbm.2013.11.003 ↗
91. Tsujita, H., Nishizaki, H., Miyake, A., Takao, S., and Komasa, S. (2021). Effect of Plasma Treatment on Titanium Surface on the Tissue Surrounding Implant Material. Int. J. Mol. Sci., 22.10.3390/ijms22136931 ↗