Overview

Metallic implant materials such as stainless steel, titanium, and cobalt-based alloys have found many applications as medical devices. This is due to their excellent mechanical properties such as fatigue strength and fracture toughness. Their durability however is dependent on their corrosion and wear resistance. The heat treatment and manufacturing method also affect these properties. The issues of adverse cellular response to wear debris from fretting fatigue and contact motion in artificial joints continue to present many challenges to the design of medical implants. The leaching of metallic ions such as nickel during the corrosion process has caused considerable concerns. This has paved way to development of new nickel-free alloys and amorphous metals that are more biocompatible.

2.1 Introduction

Metallic materials are often used to replace structural components of the human body because they surpass plastic or ceramic materials in terms of tensile strength, fatigue strength, and fracture toughness. As such, they are used in medical devices such as artificial joints, dental implants, artificial hearts, bone plates, staples, wires, and stents. They also possess better electro conductivity qualities, and hence are used for enclosing electronic devices such as pacemaker electrodes and artificial inner ears. Figure 2 1(a) shows typical applications of metallic implant devices, and Figure 2 1(b) shows a stainless steel stent used...