Dilute Cu–Al, Cu–Ti and Cu–Al–Ti alloys internally oxidized over the temperature range 1073–1323 K were investigated by X-ray diffractometry, optical and electron microscopy and microvickers hardness testing.
From X-ray diffractometry of the nitric-acid-treated residues, γ- and α–Al₂O₃ and CuAlO₂ were identified in internally oxidized Cu–Al alloys and rutile and anatase type TiO₂ in internally oxidized Cu–Ti alloys. In internally oxidized Cu–Al–Ti alloys, all of the oxides observed in the both above Cu–Al and Cu–Ti systems were identified, and no other complex oxides were detected.
By electron microscopy, it was revealed that the particle size of dispersed oxide was remarkably decreased with addition of a small amount of titanium into Cu–Al alloy. In accord with the results from electron microscopy, the microvickers hardness increased with the mass ratio of TiO₂ to total oxide.
The internally oxidized Cu–Al–Ti alloys possessed excellent qualities that belonged to the internally oxidized Cu–Al and Cu–Ti alloys.