Assessment of magnesium calcium alloys improved by rare earths addition for medical implants

Biodegradable materials are used as alternative implants for orthopedic applications due suitable strength, fatigue resistance, ductility and biocorrosion resistance which are features for biodegradable implants. Mechanical properties can be improved by adding alloying elements. The decrease of the corrosion rate of Mg can be induced by modifying the structure and phase distribution. Thus, Mg alloys have been designed to meet the requirements of bone repair implant materials by adding = Calcium and Yttrium or Gadolinium. Mg based alloy with Ca and Y/Gd had been proved to be a biocompatible material, osteoconductive and biodegradable and can be used in bone repairs. The system is defined as Mg100-(n+x) Ca(n) RE(x), varying the RE concentration in order to slow the degradation process. Beside morphological combining characterization SEM, EDX, with non-invasive testing is required to be carried out the determination of mechanical characteristics. The interest in this study is to analyze the influence of RE over elastic properties of these alloys in order to choose the best values appropriate with human bones, using Resonant Ultrasound Spectroscopy and ultrasound method.