Tailoring the pore morphology of porous nitinol with suitable mechanical properties for biomedical applications

• Porous NiTi with tailorable pore size and morphology for biomedical implants 75% recovery at 8% absolute strain.
• Spherical pores have better mechanical properties than cuboidal ones.
• Interconnected pores suitable for tissue ingrowth for biomedical applications.
• Low modulus and almost complete recovery at 2% strain; critical to mimic the bone structure.

NiTi, commercially known as Nitinol, exhibits unique properties of high recoverable strain, shape memory effect, biocompatibility, high strength, low density and stiffness. The porous structure of this material mimics the hierarchical structure of bone, which makes it a potential material for biomedical implants. Porous NiTi shape memory alloys were fabricated by pressureless sintering under vacuum using NaCl as a spacer. The porosity of the fabricated alloys was kept within the range suitable for better bone tissue ingrowth and osseointegration for bone grafting and implant applications. The effect of the shape and size of NaCl powder on the pore morphology and mechanical properties was studied. Pore morphology and size were replica of the shape of the spacer powder. Moreover, porous alloys with spherical pores showed better mechanical properties as compared to the cuboidal shape. All the foams showed low modulus and almost complete recovery at 2% strain, which is critical to mimic the bone structure for implant applications.

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