Abstract
The influence of aging, tempering and normalizing heat treatments on the properties of nickel-aluminum bronze as an important cupper base nonferrous alloy was studied and the effect of time during aging treatment wasinvestigated. Phase composition, microstructure andhardness of the alloy were determined using X-ray diffraction analysis, optical and scanning electron microscopy and micro hardnessmeasurements, respectively. Corrosion resistance of samples was evaluated by performing potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques, which were carried out in%3.5 NaCl. The results showed that tempering heat treatment removed the unstable martensitic β' phase and improved corrosion performance of the alloy. Aging treatment for 2 hours caused formation of more amount of hard κ phase and resulted in the highest hardness. It seems that formation of different phases and establishing of more localized galvanic cells caused a little increasing of corrosion current density. However, increasing of hardness and negligible drop of corrosion resistance during aging heat treatmentintroduced it as an appropriate practicalheat treatment for providing high resistance against erosion.
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