Publications
Achieving superelasticity in additively manufactured NiTi in compression without post-process heat treatment
N. S. Moghaddam, S. Saedi, A. Amerinatanzi, A. Hinojos, A. Ramazani, J. Kundin, M. J. Mills, H. E. Karaca, M. Elahinia.
Scientific Reports, 9, 41, (2019)
Abstract
Shape memory alloys (SMAs), such as Nitinol (i.e., NiTi), are of great importance in biomedical and
engineering applications due to their unique superelasticity and shape memory properties. In recent
years, additive manufacturing (AM) processes have been used to produce complex NiTi components,
which provide the ability to tailor microstructure and thus the critical properties of the alloys, such
as the superelastic behavior and transformation temperatures (TTs), by selection of processing
parameters. In biomedical applications, superelasticity in implants play a critical role since it gives the
implants bone-like behavior. In this study, a methodology of improving superelasticity in Ni-rich NiTi
components without the need for any kind of post-process heat treatments will be revealed. It will be
shown that superelasticity with 5.62% strain recovery and 98% recovery ratio can be observed in Ni-
rich NiTi after the sample is processed with 250 W laser power, 1250 mm/s scanning speed, and 80 μm
hatch spacing without, any post-process heat treatments. This superelasticity in as-fabricated Ni-rich
SLM NiTi was not previously possible in the absence of post-process heat treatments. The findings of
this study promise the fast, reliable and inexpensive fabrication of complex shaped superelastic NiTi
components for many envisioned applications such as patient-specific biomedical implants.
Keyword(s): Biomedical materials; metals and alloys
DOI: 10.1038/s41598-018-36641-4
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