Microstructural Optimization and Erosion–Corrosion Resistance of Cu-10Ni-3Al-1.8Fe-0.8Mn Alloy via Tailored Heat Treatment

This study systematically investigated the effects of tailored heat treatments on the microstructural evolution, mechanical properties, and erosion-corrosion resistance of Cu-10Ni-3Al-1.8Fe-0.8Mn alloy. Four heat treatment conditions-as-cast (AC-1); homogenized (H-2); and deformation-aged at 500 °C (D-3) and 750 °C (D-4)-were applied to elucidate the interplay between microstructure and performance. The D-3 specimen, subjected to deformation followed by aging at 500 °C for 0.5 h, demonstrated superior properties: a Vickers hardness of 118 HV5 (83.3% higher than H-2) and an erosion-corrosion rate of 0.0075 mm/a (84.1% reduction compared to H-2). These enhancements were attributed to the uniform dispersion of nanoscale Ni₃Al precipitates within the matrix, which optimized precipitation strengthening and reduced micro-galvanic corrosion. The D-3 specimen also formed a dense, crack-free Cu₂O corrosion product film with a flat matrix interface, confirmed by SEM cross-sectional analysis and electrochemical impedance spectroscopy (EIS), exhibiting the highest charge transfer resistance and film impedance.