An attempt is being made to develop novel Ni-Mo-W-Cr-Al-X alloys with ICME approach with critical experimental/simulations and processing/microstructural characterization/property evaluation and performance testing has been adopted. In this work, based on thermodynamic modeling five alloy compositions with varying Mo/W and two alloys with high tungsten modified with the addition of Al or Ti were selected and prepared. The newly developed alloys were evaluated for their response to thermal aging in the temperature range of 700 to 850 °C and corrosion in the KCl-NaCl-MgCl 2 salt under suitable conditions. Thermally aged and post-corrosion test samples were characterized to ascertain phase transformations, microstructural changes and corrosion mechanisms. Al/Ti modified alloys showed significant change in hardness after 400 hours aging at 750°C, which was found to be due to the presence of fine γ’/γ” precipitates along with plate-shaped W/Mo-rich particles. These alloys show comparable molten salt corrosion resistance as commercial alloys at 750°C for 200-hour exposures. The good corrosion behavior of these alloys may be attributed to the formation of a protective multicomponent Al-or Ti-enriched oxide as well as the unique microstructure.

Nitinol is commonly used as a retention clip to prevent backout of fixation screws in spinal anterior cervical plates (ACP). During implantation, however, there is metallic contact between the screw and retention clip. The effects of this surface damage on corrosion resistance of the Nitinol clip have not been thoroughly investigated and may be dependent on the level of screw-clip interference in the construct design. Therefore, the goal of this study is to characterize the effects on the Nitinol corrosion resistance using varying levels of screw-clip interference in a modified ACP assembly.