Eventos Anais de eventos
COBEM 2019
25th International Congress of Mechanical Engineering
ENGINEERING Ti-35Nb-Sn ALLOYS WITH GRADED ELASTIC MODULUS BY LASER MELTING FOR BIOMEDICAL APPLICATIONS
Submission Author:
Juliane Ribeiro da Cruz Alves , SP
Co-Authors:
Juliane Ribeiro da Cruz Alves, Rodnei Bertazzoli
Presenter: Juliane Ribeiro da Cruz Alves
doi://10.26678/ABCM.COBEM2019.COB2019-2418
Abstract
To minimize the stress-shielding of bones, implants with low elastic modulus are necessary. However, this eventually leads to an increase in implant-bone shear stresses, that can compromise the implant success. Simulations consistently indicate that optimum implant design requires a structure with variable Young’s modulus. In this work, we wish to engineer Ti-35Nb-(0, 2 and 4)Sn mass % alloys with graded elastic modulus by laser melting. Cold-rolled 2 mm thick plates were laser melted. and microstructure characterization was carried out on the melted track transverse cross-section by optical and electron microscopy, x-ray diffraction, EBSD, nanoindentation analysis and Vickers microhardness. Thermal simulation under high heating rates with simultaneous synchrotron XRD was performed to assess phase transformations. Results show that cold-rolling promoted the formation of stress-induced α”-martensite with strong <010>α” texture in Ti-35Nb and Ti-35Nb 2Sn alloys. In addition, Ti-35Nb 2Sn alloy also developed {001}〈100〉β texture, with low β-phase stability. This resulted in an initial Young’s modulus of 57 GPa and 52 GPa, respectively. With laser melting, elastic modulus was locally increased up to 78 GPa, in Ti-35Nb alloy, and to 72 GPa. in Ti-35Nb-2Sn alloy. This was associated to martensitic reversion and reduction of {001}〈100〉β texture. On the other hand, Ti-35Nb-4Sn alloy presented high β phase stability and an initial elastic modulus of 65 GPa, that was not significantly affected by laser melting. Results show that laser melting can effectively produce Ti-35Nb and Ti-35Nb-2Sn implants with graded elastic modulus.
Keywords
β Ti alloy, Laser welding, Low elastic modulus, Functionally graded properties
