Microstructure, electrochemical, wear and corrosive wear performance of laser-based powder bed fusion and wrought biomedical Ti-6Al-4V alloys
(1. Laboratory of Applied Metallurgy, Department of Materials Science and Engineering,
School of Engineering, University of Ioannina, Ioannina 45110, Greece;
2. Institute of Materials Science and Computing, University Research Center of Ioannina (URCI),
Ioannina 45110, Greece;
3. Department of Physics, Pryazovskyi State Technical University, Dnipro 49044, Ukraine;
4. Institute of Materials Research of Slovak Academy of Sciences, Kosice 04001, Slovakia)
School of Engineering, University of Ioannina, Ioannina 45110, Greece;
2. Institute of Materials Science and Computing, University Research Center of Ioannina (URCI),
Ioannina 45110, Greece;
3. Department of Physics, Pryazovskyi State Technical University, Dnipro 49044, Ukraine;
4. Institute of Materials Research of Slovak Academy of Sciences, Kosice 04001, Slovakia)
Abstract: Wrought and laser powder bed fusion (LPBF) Ti-6Al-4V (Ti-6-4) specimens were comparatively evaluated, with the objective to determine LPBF Ti-6Al-4V’s suitability for biomedical applications. Testing included nanoindentation, cyclic polarization in simulated body fluid (SBF, 37 °C), and dry and SBF “ball-on-plate” sliding. Wrought Ti-6-4 exhibited a lamellar α+β microstructure, whereas LPBF Ti-6-4 displayed a fine-grained α￠-martensite microstructure. LPBF Ti-6-4 demonstrated ~3% higher indentation modulus and ~32% higher hardness, while wrought Ti-6-4 showed ~8% higher plasticity. Both alloys exhibited low corrosion rates (10-5 mA/cm2 order) and true passivity (10-4 mA/cm2 order). No localized corrosion was observed in either two alloys, except for occasional metastable pitting in the LPBF alloy. However, LPBF Ti-6-4 presented higher corrosion rate and passive current, ascribed to its martensitic structure. During dry sliding, LPBF Ti-6-4 exhibited ~14% lower volume loss compared to wrought Ti-6-4. Sliding in SBF increased volume losses for both alloys, with wear resistances nearly equalized, as the advantage of LPBF Ti-6-4 decreased due to more intense wear-accelerated corrosion induced by the stressed martensite. Overall, the results demonstrate the suitability of LPBF Ti-6-4 for biomedical uses.
Key words: biomedical Ti-6Al-4V alloy; laser-based powder bed fusion; electrochemical corrosion; nanoindentation; sliding wear; wear-corrosion synergism