Healing cracks in additively manufactured NiTi shape memory alloys

The pursuit of enhancing NiTi superelasticity through laser powder bed fusion (L-PBF) and [001] texture creation poses a challenge due to increased susceptibility to hot cracking in the resulting microstructure with columnar grains. This limitation restricts NiTi's application and contributes t...

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Bibliographic Details
Published in:Virtual and physical prototyping 2023-12, Vol.18 (1)
Main Authors: Zhu, Jia-Ning, Ding, Zhaoying, Borisov, Evgenii, Yao, Xiyu, Brouwer, Johannes C., Popovich, Anatoly, Hermans, Marcel, Popovich, Vera
Format: Article
Language:English
Subjects:
healing crack
laser powder bed fusion
niti alloys
spark plasma sintering
superelasticity
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Summary:The pursuit of enhancing NiTi superelasticity through laser powder bed fusion (L-PBF) and [001] texture creation poses a challenge due to increased susceptibility to hot cracking in the resulting microstructure with columnar grains. This limitation restricts NiTi's application and contributes to material waste. To overcome this, we introduce a pioneering approach: utilising spark plasma sintering (SPS) to heal directional cracks in [001] textured L-PBF NiTi shape memory alloy. Diffusion bonding and oxygen utilisation for Ti2NiOx formation was found to successfully heal the cracks. SPS enhances mechanical properties, superelasticity at higher temperatures, and two-way shape memory strain during thermomechanical cycling. This work provides an alternative solution for healing cracks in L-PBF parts, enabling the sustainable reuse of cracked materials. By implementing SPS, this approach effectively addresses hot cracking limitations, expanding the application potential of L-PBF NiTi parts while improving their functional and mechanical properties.
ISSN:1745-2759
1745-2767
DOI:10.1080/17452759.2023.2246437