The surface reaction of Co 3Ti alloys (with and without Fe) with water vapor was investigated by using Auger electron spectroscopy (AES). The results showed that the rate of the surface reaction is much lower in Co 21 5Ti 3Fe alloy as compared with Co 3Ti (Co 23Ti) alloy. The surface reaction of Co 21 5Ti 3Fe alloy with water vapor saturates at exposure of 2×10 -3 Pa·s, but it does not saturate even at 0 1 Pa·s exposure for Co 3Ti alloy without Fe. The results also indicated that the kinetic of the surface reaction of Co 21 5Ti 3Fe with water vapor is much smaller than that of Co 3Ti at the same exposure. All the above results illustrate that the suppression of environmental embrittlement by addition of Fe to Co 3Ti alloy is attributed to its reduction of the surface reaction kinetics with water vapor.
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