Abstract:By means of scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, the oxide layers on equiatomic TiNi shape memory alloy oxidized in the temperature range from room temperature to 800℃were studied. The results showed that the thin oxide film naturally formed at room temperature contains Ti element in TiO₂state and part of Ni element in Ni₂O₃state, leaving other Ni still in metallic state; The thin oxide films formed at 300~500℃are characterized by enriched Ti and depleted Ni, both in completely oxidized state. Thick scaling layers were formed above 700℃, which are proved to be composed of an outer TiO2layer dissolved by small amount of Ni and an inner pure Ni₃Ti layer.

Key words: TiNi shape memory alloy　oxidation　surface modification