Virtual and Physical Prototyping (Dec 2023)

Healing cracks in additively manufactured NiTi shape memory alloys

  • Jia-Ning Zhu,
  • Zhaoying Ding,
  • Evgenii Borisov,
  • Xiyu Yao,
  • Johannes C. Brouwer,
  • Anatoly Popovich,
  • Marcel Hermans,
  • Vera Popovich

Journal volume & issue
Vol. 18, no. 1


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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.