Electrochemical corrosion behavior and mechanical properties of Ti–Ag biomedical alloys obtained by two powder metallurgy processing routes

Abstract

Titanium is frequently used as a biomaterial and the importance of Ti–Ag alloys has increased thanks to the antibacterial behavior of silver. In this study, Ti–Ag alloys (5, 10 and 15 wt% Ag) were obtained by two different powder metallurgy routes: blended elemental (BE) and mechanical alloying (MA). The influence of the powder mixture methodology on both microstructure and electrochemical behavior was analyzed. Powders were compacted at 600 and 900 MPa, respectively, and sintered at high vacuum for 3 h at 950 °C. The obtained Ti–Ag alloys were microstructurally characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD), and mechanically tested by hardness and bending tests. Electrochemical tests were run using a three-electrode cell in an artificial Fusayama saliva solution. Open-Circuit Potential (OCP), polarization curves, potentiostatic tests and Electrochemical Impedance Spectroscopy (EIS) techniques were employed to evaluate the corrosion resistance of the studied Ti–Ag alloys. The initial characteristics of powders before sintering and after blend/alloying modified the electrochemical behavior of the Ti–Ag-sintered alloys and were determined. The samples obtained with the BE powders better resisted corrosion than the MA samples, and this behavior was directly related to the quantity and distribution of intermetallic Ti2Ag. A large quantity of intermetallics present on both the edge and inside grains reduced the corrosion resistance of TiAg alloys.