Nitinol memory alloys (NiTi) have been used in clinical practice for more than 30 years as bone implant materials due to their unique functional properties, especially shape memory effect, hyperelasticity, good biocompatibility and biomechanics. One of the critical issues often encountered in orthopedic biomaterials is the "stress shielding" created by the mismatch of elastic modulus between bone tissue and implant material, which can lead to implantation failure. In order to reduce the elastic modulus of implanted materials, pores are introduced to form porous materials that mimic natural bone structures and mechanical properties. The porous structure not only modulates the elastic modulus of the material and improves the biomechanical compatibility of the implant, but also provides the necessary framework for osteocytes to grow into the pores and integrate with the host tissue.

In this work, porous NiTi intermetallic compounds were successfully prepared by a time-saving and energy-saving thermal explosion reaction using four particle sizes of Ni powder (99.9%, 74 μm, 38 μm, 5 μm, 100–200 nm) and Ti powder (99.99%, ≥ 300 mesh). The research results were published in Intermetallics (JCR Q1, IF=4.4) with the title “Mechanical and electrochemical properties of porous NiTi intermetallics synthesized via rapid thermal explosion”.

Fig. 1 Thermal explosion images of S1 NiTi.

Fig. 2 EPMA mapping for the NiTi samples (a) S1, (b) S2, (c) S3, (d) S4.

Fig. 3 (a) evolution of OCP with time recorded for porous NiTi in PBS solutions at 37 ◦C ± 5 ◦C, (b) potential polarization curves of porous NiTi in PBS solutions at 37 ◦C ± 5 ◦C, (c) Nyquist curves of porous NiTi intermetallics in PBS.

Authors: Xuewei Xu, Zhichan Shang, Baojing Zhang, Xiaoping Cai**, Peizhong Feng* 

Link: https://www.sciencedirect.com/science/article/pii/S0966979523003424

DOI: https://doi.org/10.1016/j.intermet.2023.108162

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