Passive metals and alloys depend on the durability of passive oxide films for high corrosion resistance.
This paper discusses the durability of the passive film on alloy 22 (a Ni-Cr-Mo alloy) as a function of
chemical, thermal and mechanical durability. The durability of the passive film on alloy 22 was
compared and contrasted with that of a corrosion resistant, iron-based structurally amorphous alloy,
SAM1651 and with less corrosion resistant alloys such as 316L SS and AL6XN. The chemical and
thermal durability were determined by the breakdown and repassivation response of the passive film and
by the ability of the passive film to stifle the corrosion after initiation of severe localized corrosion. The
mechanical durability of passive films was studied by examining their reformation behavior after
scribing the passive film with a diamond tip. The passive film on alloy 22 showed excellent durability
under aggressive conditions accompanying a detrimental chemical environment, high temperature and
mechanical damage.