Corrosion characteristics of α-Ti and Ti₂Cu composing Ti-Cu alloys

A series of binary Ti-Cu alloys containing 5-20 mass% Cu was prepared, and the corrosion behavior of α-Ti and Ti₂Cu composing the Ti-Cu alloys were examined based on the anodic polarization curves and released ions in 0.9% NaCl and 1% lactic acid solutions. In both solutions, the Ti-Cu alloys showed the same anodic polarization curves as titanium in the condition below 1.4 V. However, precipitation of Ti₂Cu contributed to a small increase in current densitiy in the transpassive region beyond 1.4 V. The amount of Cu ions released from Ti₂Cu was 0.260 and 1.003 (μg/cm ²/7 days) in 0.9% NaCl and 1% lactic acid solutions respectively. Although these values were larger than those from α-Ti (0.0379 ± 0.0041 and 0.0962 ± 0.0327 (μg/cm²/7 days) in NaCl and lactic acid solutions respectively), they were not greater than those from type 4 gold alloy under the same conditions.