Optimizing Heat Treatment to Reduce Failure Rates in Cu-P-Ag Brazing Alloys: A Microstructural, Mechanical, and Corrosion Study

Abstract In this study, the effects of heat treatment on the mechanical and corrosion performance of Cu-P-Ag alloys were systematically investigated with the aim of achieving an optimized balance between flexibility, mechanical strength, and electrochemical stability. Cu-P-Ag alloys are widely used in industrial brazing and electronic applications due to their high electrical conductivity, thermal performance, and corrosion resistance. However, improving mechanical strength often compromises flexibility and increases residual stress causing early fractures during production. To address this challenge, the alloy was subjected to controlled heat treatments at various temperatures (100 to 550 °C). Microstructural evolution was analyzed via SEM and XRD, while hardness and residual stress measurements provided insights into mechanical behavior. The results reveal that heat treatment at 400 °C significantly enhances flexibility and reduces internal stress, primarily due to the uniform and fine precipitation of β-Ag phases and the formation of a uniform and thermodynamically stable microstructure. In parallel, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and Mott–Schottky analysis were employed to assess corrosion resistance in 0.9% NaCl solution. The findings indicate that the passive films formed post-treatment at 400 °C exhibit superior protective characteristics, attributed to improved film compactness and reduced surface heterogeneity. This optimized heat treatment condition successfully enhances both mechanical and electrochemical performance, making the Cu-P-Ag alloy more suitable for high-performance industrial applications where strength, softness, and corrosion resistance need to be balanced.