Healing cracks in additively manufactured NiTi shape memory alloys
Jia Ning Zhu (TU Delft - Team Vera Popovich)
Zhaoying Ding (TU Delft - Team Marcel Hermans)
E. Borisov (Peter the Great Saint-Petersburg Polytechnic University)
Xiyu Yao (Southern University of Science and Technology )
J.C. Brouwer (TU Delft - Team Marcel Hermans)
Anatolii Popovich (Peter the Great Saint-Petersburg Polytechnic University)
Marcel Hermans (TU Delft - Team Marcel Hermans)
Vera A. Vera (TU Delft - Team Vera Popovich)
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Abstract
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.
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