強度・曲げ加工性・疲労特性に優れたCu–Ti–Al–Fe系合金の開発

抄録

The effects of Al and Fe co–doping with Cu–Ti alloys on microstructure, strength, bend formability, and fatigue properties were investigated. Al and Fe co–doping with Cu–Ti alloys leads to (i) suppression of coarsen discontinuous precipitate β–Cu₄Ti on the grain boundaries, (ii) grain refinement during solution heat treatment caused by pinning effect by FeTi particles, and (iii) formation of extra–precipitates such as Cu₂TiAl in Al–doped alloys and FeTi and (Cu,Fe)₄Ti₃ in Fe–doped alloys. The microstructural evolutions in the Cu–Ti–Al–Fe alloy were contributed to the improvement of strength, bend formability, and fatigue properties, in comparison with those of binary Cu–Ti and ternary Cu–Ti–Al and Cu–Ti–Fe alloys. Especially, fatigue property was significantly improved in the Cu–Ti–Al–Fe alloy, which was explained by suppression of the initiation and growth of fatigue cracks through small Cu₂TiAl particles on the fine grain boundaries. Therefore, it can be concluded that the Cu–Ti–Al–Fe alloy should be expected as an applicable material for compact springs and connectors in information communication devices.