Enhancement of Mechanical Properties and Corrosion Resistance in SiCw Reinforced Al–Zn–Mg–Cu Composites via Controlled Aging Treatments

In this study, a high-performance aluminum matrix composite reinforced with SiC whiskers (SiCw), exhibiting excellent mechanical properties and outstanding corrosion resistance, was successfully fabricated. The composite was prepared via ball-milling, hot isostatic pressing (HIP), solution treatment, and aging. It was observed that the coherent interface structure of SiCw/MgAl2O4/Al enhanced the bonding between the particles and the matrix. In the T4 aging state, the composite demonstrated superior properties, with an elastic modulus of 104.9 GPa, a yield strength of 629.2 MPa, and an ultimate tensile strength of 680.6 MPa. Aging treatment facilitated Mg migration to MgAl2O4, reducing the Mg content in the matrix and consequently decreasing the composite’s strength. The T6I4 aging process promoted the transformation of precipitates from GP zones + η' (T4) to η + η' (T6I4). Post T6I4 aging, the grain boundaries were remarkably clean, free of aging precipitates and O element segregation. Additionally, the galvanic corrosion current density in 3.5 wt % NaCl solution was as low as 9.05 × 10–8 A cm–2, indicating excellent corrosion resistance.