Microstructure and properties of a HIP manufactured SiCp reinforced high alloyed Al-Zn-Mg-Cu-Zr-Ti aluminum matrix composite

In this study, a hot isostatic pressing (HIP) manufactured SiC particles (SiCp) reinforced high alloyed Al-Zn-Mg-Cu-Zr-Ti aluminum matrix composite was fabricated through ball-milling, HIP, homogenization, hot extrusion, solution treatment, and aging treatment. The results showed the presence of an interfacial reaction layer, MgAl2O4, around the SiCp, which enhanced the bonding between the particles and the matrix. The aging treatment resulted in the formation of different aging precipitates, which were featured by GP zone for T4, GP zone + η' (metastable MgZn2) + η (stable MgZn2) for T6 and GP zone + η' (metastable MgZn2) for T6I4. The composite samples of T4, T6, and T6I4 exhibited different mechanical properties. Specifically, the elastic modulus was measured as 102.9, 103.4, and 102.3 GPa, the yield strength was 685.3, 598.1, and 619.7 MPa, the ultimate tensile strength was 713.6, 618.9, and 633.3 MPa, and the elongation was 2.2%, 1.8%, and 2.8%, respectively. Furthermore, the corrosion behavior of the composite was evaluated through electrochemical, intergranular corrosion, and exfoliation corrosion. The corrosion current density was found to be 3.17×10-7, 4.97×10-7, and 3.67×10-7 A·cm-2, the corrosion potential was measured as -0.70, -0.81, and -0.56 V, and the maximum intergranular corrosion depth was 139.9, 167.8, and 106.2 μm for T4, T6, and T6I4, respectively. The severity of exfoliation corrosion varied, with T4 showing severe pitting, T6 exhibiting moderate pitting, and T6I4 displaying slight pitting. The strengthening mechanism and load transfer strengthening of the composites were discussed based on theoretical calculations, and the corrosion mechanisms were analyzed in detail.