Metals (Chapter 5)

Abstract

Metals are the materials of choice for many structural implantable device applications and there is no reason to expect a change in the short or medium term. Processing-structure relationships are described with special emphasis for Ti and Ti-base alloys, austenitic stainless steel, and Co-based alloys, but other metallic materials in use are also presented. Mechanical properties and their relationship with the microstructure are summarized for static and dynamic loads. Chemical properties focus on the corrosion behavior, nature of the passive films, and the closely related ion release topic. Surface energy and surface charges, which are relevant for the understanding of the biological response, are also revised. A detailed overview of the new family of Ti-base alloys with a lower Young's modulus, Ni-free Fe-based alloys, nanostructured alloys, biodegradable alloys, and porous metals for the fabrication of scaffolds, is presented. The modern engineering techniques used for the fabrication of custom-made metallic implants are also considered.