<p>Ti-Cu alloys, as a precipitation-hardened ones, were investigated to balance mechanical properties and corrosion ones, where limited Cu up to 1 wt.% was added. Limiting the Cu addition maintained the α-Ti phase, but the grain refining occurred as a result of the precipitate (embryo) formation at grain boundaries. SEM and TEM results showed the presence of the precipitates at grain boundaries for the Ti-1.0Cu alloy but there was no evidence on the precipitate for the Ti-0.5Cu alloy. Only EPMA analysis revealed the Cu rich zone at the grain boundary, indicating the existence of the precipitate (or embryo). The added Cu utilized not only solid solution element but precipitate formation, which improved mechanical properties such as hardness and wear resistance. In particular, the precipitate seemed to exert an impact on wear mode. The transition from adhesive wear to abrasive wear occurred with increasing the Cu content, indicating the precipitate would work as a lubricant. The precipitate also affected corrosion properties. Corrosion resistance against the high concentrated H₂SO₄ was improved with the addition of Cu. The positive shift of corrosion potential with the Cu addition seemed to be ascribed to the cathodic modification of the precipitate and thus, the improved passivation stability retarded the dissolution of the passivation layer in the high concentrated H₂SO₄ solution. So, the highest Cu content showed the lowest corrosion rate due to the largest amount of the precipitates.</p>