Corrosion Resistance of Amorphous FeNiCrW Alloys

The corrosion resistance of amorphous FeNiCrW alloys prepared by cosputtering of Type 304 stainless steel and W was studied in chloride solutions by potentiodynamic polarization methods. In both neutral and acidic solutions, the as-deposited amorphous FeNiCrW alloys had excellent corrosion resistance, similar to that of metal-metalloid amorphous alloys containing Cr and P. This result demonstrates that P is not essential for producing corrosion resistance in amorphous materials. More significantly, the corrosion resistance of amorphous FeNiCrW alloys in neutral solutions was preserved after heat treatment at the crystallization temperature. In acidic solutions, these heat treated alloys exhibited a slight increase in active dissolution but remained highly passivated at high potentials. The retention of corrosion resistance of the heat treated amorphous FeNiCrW alloys was attributed to a two stage crystallization process wherein fine BCC crystallites were formed in the amorphous matrix with no segregation of impurities at boundaries.