Cyclic deformation behaviour and fatigue induced surface damage of titanium alloys in simulated physiological media

In this investigation, the cyclic deformation behaviour of the binary titanium alloys Ti-6Al-4V and Ti-6Al-7Nb was characterized in axial stress controlled constant amplitude and load increase tests as well as in load courses based on gait patterns from human walking [1]. The influence of slight differences of the alloy microstructures as well as different clinically relevant surface treatments (polishing, thermal and anodic oxidising, corundum grit blasting) on the fatigue behaviour was investigated. The constant amplitude tests and gait pattern tests were realized in oxygen saturated Ringer's solution. All results were characterized by mechanical hysteresis and temperature measurements, respectively. In addition, the change of the free corrosion potential and the corrosion current during testing in quasi-physiological media indicated surface deformations such as slip bands, intrusions and extrusions or finally microcracks. Microstructural changes on the specimen surfaces were examined by scanning electron microscopy (SEM).