The influence of Cu content on the corrosion resistance of Co-Fe-Cu magnetic alloys in aqueous environments

To increase magnetic storage density, it is necessary to develop recording heads using materials with optimised magnetic properties. Several works hav e revealed the high Bs Co90Fe10 alloys (1.8-2.0 T). However, coercivity of these alloys is too high and the addition of a third element such as copper improves its soft magnetic properties and resistivity. Magnetic properties of these materials are very attractive and the corrosio n behaviour is investigated by electrochemical tests. The copper element im proves the passivation ability of CoFeCu alloys up to 2.7 % content. Moreover, susceptibility to pitting corrosion is greatly decreased and even suppressed for higher Cu contents.