OXIDE FILM ON EQUIATOMIC TiNi SHAPE MEMORY ALLOY

１ＩＮＴＲＯＤＵＣＴＩＯＮＥｑｕｉａｔｏｍｉｃＴｉＮｉｓｈａｐｅｍｅｍｏｒｙａｌｏｙ（ＳＭＡ）ｉｓａｎｏｖｅｌａｎｄｐｒｏｍｉｓｉｎｇｂｉｏｍａｔｅｒｉａｌｄｕｅｔｏｉｔｓｕｎｉｑｕｅａｎｄｅｘｃｅｌｅｎｔｓｈａｐｅｍｅｍｏｒｙｅｆｅｃｔａｎｄｓｕｐ...

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 TiO 2 state and part of Ni element in Ni 2O 3 state, 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 TiO 2 layer dissolved by small amount of Ni and an inner pure Ni 3Ti layer.