Zirconium Alloys for Orthopedic Applications

Abstract

Physical and chemical properties of zirconium (Zr) are introduced and the features and differences from titanium (Ti) are pointed out. Zr is principally applied to the nuclear power industry because of its low thermal neutron cross section. For medical applications, a Zr alloy (Zr-2.5Nb) is used in total knee and hip replacements because of its excellent wear resistance. The dense and adherent oxide layers are formed on the surface of Zr alloy and contribute to improving its wear resistance. Zr is also promising for suppressing artifacts in magnetic resonance images, because it shows lower magnetic susceptibility than that of SUS, Co-Cr alloy, and Ti. The magnetic susceptibilities of the Zr alloys are sensitive to their phase constitutions. Magnetic susceptibility in addition to mechanical properties could be controlled by changing the composition depending on the requirements for medical devices under magnetic resonance imaging (MRI).