Adjustment of AgCaLa Phases in a FeMn Matrix via LBM for Implants with Adapted Degradation

Abstract

For many applications, implants overtake body function for a certain time. Bioresorbable implants reduce patient burden as they prevent adverse consequences due to remaining implants or operations for removal. Such materials are in clinical use but do not fulfill the requirements of all applications. Iron (Fe) is promising to develop further bioresorbable materials as it offers biocompatibility and good mechanical properties. Alloying, e.g., with manganese (Mn), is necessary to adapt the mechanical behavior and the degradation rate. However, the degradation rate of FeMn is too low. The creation of phases with high electrochemical potential evokes anodic dissolution of the FeMn, increasing the degradation rate. Therefore, silver (Ag), which is insoluble with Fe, has high potential, is biocompatible, and offers antibacterial properties, can be used. Powder-based processes such as laser beam melting (LBM) are favorable to process such immiscible materials. A degradable Ag alloy has to be used to enable the dissolution of Ag phases after the FeMn. This study reports first about the successful processing of FeMn with 5 wt.% of a degradable Ag–calcium–lanthanum (AgCaLa) alloy and enables further targeted adaption due to the gained understanding of the effects influencing the morphology and the chemical composition of the Ag phases.