GRAIN SIZE EVOLUTION, MECHANICAL AND CORROSION BEHAVIOUR OF PRECIPITATE STRENGTHENED Cu-Ni ALLOY

The grain size characteristics, mechanical properties, and corrosion resistance of Cu-10Ni alloy heat treated at three different temperatures and times were investigated and compared with the synthesized alloy. Mechanical properties such as ultimate tensile strength (UTS), ductility, hardness, and impact strength were determined in the research work. An optical metallurgical microscope was used to examine the structural properties. ImageJ software was also used to measure the grain size distribution of the alloys. The corrosion behaviour of the produced Cu-10Ni alloys is analyzed by potentiodynamic polarization and Electrochemical Imped-ance Spectroscopy (EIS). After corrosion testing, the surface morphology of the exposed samples is analyzed by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy. The results indicated that average grain size and level of grain distribution improve mechanical properties and corrosion resistance of Cu-10Ni alloy. The precipitate-strengthened Cu-10Ni alloys had a lower corrosion rate compared to as-cast alloys, and their ultimate tensile strength, ductility, and hardness improved with decreasing average grain size distribution. The non-heat treated Cu-10Ni alloy showed a peak value of corrosion rate and average grain size, but a lower value of mechanical properties. An increase in residual stress follows an increase in grain size distribution, which lowers the strength and increases corrosion rates due to more active sites of activation energy. The surface analysis confirms the presence of a protective film on the exposed alloy surface. The research outcome has enabled the improvement of the mechani-cal and corrosion properties of Cu-10Ni alloys as a component for marine and automobile applications.