STRUCTURE, CRYSTALLIZATION AND ELECTROCHEMICAL CORROSION BEHAVIOR OF AMORPHOUS CU66TI34 ALLOY

The effect of thermally induced structural changes on electrochemical corrosion behaviour of amorphous Cu66Ti34 alloy is studied using elect rochemical potentiodynamic polarization technique in conjunction with XRD, TEM and DTA. The heat treatment has been carried out at two tempe ratures: 300 degrees C - where the process of structural relaxation is only possible and 500 degrees C - where crystallization of the alloy occurs. As model corrosive media 1N H2SO4 and 1N HNO3 solutions are us ed. The short range order of the amorphous samples is studied with the total pair correlation function, Some changes of the interatomic dist ances and a tendency to increasing of the density of the amorphous str ucture after low temperature heating are established. The crystallizat ion leads to formation of Cu3Ti2, beta-Cu3Ti and Cu2Ti crystalline pha ses. It has been found that structural relaxation map have a beneficia l effect on the susceptibility of the amorphous alloy to passivation, while crystallization lowers considerably its corrosion resistance.