Corrosion performance of Ti-Cu alloys targeted for biomedical applications

The Thermo-Calc™ program and TTTI3 database were used to predict the phases in Ti-Cu with 5, 25, and 40 wt% Cu. Based on the predicted results, experimental work was conducted and the Ti-Cu alloys were produced in a button arc furnace, and characterised in the as-cast and the annealed condition (900°C) followed by water quenching. Microstructures and compositions were determined using an electron probe micro-analyser, and the phases were identified by X-ray diffraction. The corrosion performance was measured by potentiodynamic polarisation in a phosphate buffered saline solution at 37 °C at 7.4 pH while purging with nitrogen gas. The Ti-5Cu and Ti-25Cu alloys comprised (αTi) and Ti2Cu phases, the Ti-40Cu alloy comprised Ti2Cu and TiCu. Although the addition of copper decreased the corrosion performance by down to 75%, the corrosion rates were still within the acceptable range (0.02-0.13 mm/y) for biocompatibility of metallic implants. Annealing at 900 °C did not improve the corrosion performance.