TY - JOUR
T1 - Selective laser melting of high-strength, low-modulus Ti–35Nb–7Zr–5Ta alloy
AU - Ummethala, Raghunandan
AU - Karamched, Phani S.
AU - Rathinavelu, Sokkalingam
AU - Singh, Neera
AU - Aggarwal, Akash
AU - Sun, Kang
AU - Ivanov, Eugene
AU - Kollo, Lauri
AU - Okulov, Ilya
AU - Eckert, Jürgen
AU - Prashanth, K. G.
PY - 2020/12
Y1 - 2020/12
N2 - The state-of-the-art alloys for load-bearing implant applications lack the necessary functional attributes and are largely a compromise between biocompatibility and mechanical properties. While commercial alloys pose long-term toxicity and detrimental stress shielding effects, the newly developed alloys are closing in on the gaps, however, falling short of the desired elastic modulus necessary to rule out stress shielding. In this work, we report the fabrication of a low modulus β-Ti alloy, Ti–35Nb–7Zr–5Ta (TNZT), by selective laser melting (SLM) with optimized laser parameters. The as-prepared SLM TNZT shows a high ultimate tensile strength (~630 MPa), excellent ductility (~15%) and a lower elastic modulus (~81 GPa) when compared to the state-of-the-art cp-Ti and Ti-based alloys. The mechanical performance of the as-printed TNZT alloy has been examined and is correlated to the microstructure (grain structure, phase constitution and dislocation density). It is proposed that a high density of GND (geometrically necessary dislocations), resulting from rapid cooling, in the as-prepared condition strengthens the alloy, whereas the single phase β-bcc crystal structure results in lowering the elastic modulus. High grain boundary area and a preferred crystal orientation of {200} planes within the bcc crystal lattices contribute to an additional drop in the elastic modulus of the alloy. It is shown that the TNZT alloy, processed by SLM, demonstrates the best combination of strength and modulus, illustrating its potential as a promising biomaterial of the future.
AB - The state-of-the-art alloys for load-bearing implant applications lack the necessary functional attributes and are largely a compromise between biocompatibility and mechanical properties. While commercial alloys pose long-term toxicity and detrimental stress shielding effects, the newly developed alloys are closing in on the gaps, however, falling short of the desired elastic modulus necessary to rule out stress shielding. In this work, we report the fabrication of a low modulus β-Ti alloy, Ti–35Nb–7Zr–5Ta (TNZT), by selective laser melting (SLM) with optimized laser parameters. The as-prepared SLM TNZT shows a high ultimate tensile strength (~630 MPa), excellent ductility (~15%) and a lower elastic modulus (~81 GPa) when compared to the state-of-the-art cp-Ti and Ti-based alloys. The mechanical performance of the as-printed TNZT alloy has been examined and is correlated to the microstructure (grain structure, phase constitution and dislocation density). It is proposed that a high density of GND (geometrically necessary dislocations), resulting from rapid cooling, in the as-prepared condition strengthens the alloy, whereas the single phase β-bcc crystal structure results in lowering the elastic modulus. High grain boundary area and a preferred crystal orientation of {200} planes within the bcc crystal lattices contribute to an additional drop in the elastic modulus of the alloy. It is shown that the TNZT alloy, processed by SLM, demonstrates the best combination of strength and modulus, illustrating its potential as a promising biomaterial of the future.
KW - Biomaterials
KW - Elastic modulus
KW - Microstructure evolution
KW - Selective laser melting
KW - Ti–35Nb–7Zr–5Ta
UR - http://www.scopus.com/inward/record.url?scp=85094315675&partnerID=8YFLogxK
U2 - 10.1016/j.mtla.2020.100941
DO - 10.1016/j.mtla.2020.100941
M3 - Article
AN - SCOPUS:85094315675
SN - 2589-1529
VL - 14.2020
JO - Materialia
JF - Materialia
IS - December
M1 - 100941
ER -