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Additively Manufactured NiTi Implants

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Figure 21. (A) The mean local displacements owing to scaffold deformation. (B) The mean local plane strains in the three orthogonal directions
(a-a, b-b, c-c, d-d are the cross-sections in different positions and directions) [112] (Reprinted from Acta Biomaterialia, 10(2), T. Bormann,
G. Schulz, H. Deyhle, et al., combining micro-computed tomography and three-dimensional registration to evaluate local strains in shape
memory scaffolds, 1024–1034, Copyright (2014), with permission from Elsevier).

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G H J

Figure 22. (A) Macro image of Cancer pagurus. (B-D) Top-surface morphology of Cancer pagurus at different magnifications. (E and F)
Cross-sectional fracture structure at different magnifications. (G and H) Cross-sectional structure after polishing. (I) A multi-pore structure.
(J) A helicoidal structure [114] (Reprinted from Applied Surface Science, 469, C. Ma, D. Gu, K. Lin et al., selective laser melting additive
manufacturing of Cancer pagurus’s claw inspired bionic structures with high strength and toughness, 647–656, Copyright (2019), with
permission from Elsevier).
tensile strain of the obtained lath SLM-NiTi is 15.6%, of SLM-NiTi parts. When manufacturing SLM-NiTi
which is more than twice the best-reported ones. Besides, in a high-oxygen atmosphere (>25 ppm), the authors
parts with complex shapes show 99% shape memory believed that oxygen would destroy the grain boundary
recovery after 50% compression deformation. layer by layer, ultimately destroying the ductility of
Wang et al. [119] studied the effects of scanning a part. Reducing the oxygen content of the chamber is
speed, hatch distance, and laser power on the phase more important for improving the ductility of parts than
change behavior and mechanical/functional properties optimizing laser parameters [120] . Despite the existence of

30 International Journal of Bioprinting (2021)–Volume 7, Issue 2