Abstract
In this work, NiTi alloy parts were fabricated using laser powder bed fusion (LBPF) from pre-alloyed NiTi powder and in situ alloyed pure Ni and Ti powders. Comparative research on the corrosive and biological properties of both studied materials was performed. Electrochemical corrosion tests were carried out in phosphate buffered saline at 37 °C, and the degradation rate of the materials was described based on Ni ion release measurements. Cytotoxicity, bacterial growth, and adhesion to the surface of the fabricated coupons were evaluated using L929 cells and spherical Escherichia coli (E. coli) bacteria, respectively. The in situ alloyed NiTi parts exhibit slightly lower corrosion resistance in phosphate buffered saline solution than pre-alloyed NiTi. Moreover, the passive layer formed on in situ alloyed NiTi is weaker than the one formed on the NiTi fabricated from pre-alloyed NiTi powder. Furthermore, in situ alloyed NiTi and NiTi made from pre-alloyed powders have comparable cytotoxicity and biological properties. Overall, the research has shown that nitinol sintered using in situ alloyed pure Ni and Ti is potentially useful for biomedical applications.
Highlights
Personalised implants and medical instrumentation that can be adapted to the anatomy and needs of a particular patient, may bring many benefits to the healing process and improved quality of life
The corrosion and biological properties of NiTi pre-alloyed and Ni+Ti unalloyed powders used in laser powder-bed fusion (LPBF) manufacturing of test coupons with an Ni:Ti ratio of unalloyed powders used in LPBF manufacturing of test coupons with an Ni:Ti ratio of
The form of batch powders used during LBPF determined the microstructure and phase composition of the alloys the LPBF-printed coupons
Summary
Personalised implants and medical instrumentation that can be adapted to the anatomy and needs of a particular patient, may bring many benefits to the healing process and improved quality of life. The critical issue of medical devices for skeletal reconstruction is to adjust their mechanical properties in relation to their attachment to the surrounding bone [4,5,6]. The currently predominant alloy for these devices, Ti-6Al-4V, often presents a mismatch between bone and device mechanical properties. This may lead surgically reconstructed bone to fail due to stress shielding and/or device failure due to stress concentration [7,8,9]. NiTi alloys have been recently shown to be promising materials for reducing the risk of stress shielding and hardware failure due to their low stiffness provided by superelasticity and shape memory behaviour [10,11,12].
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