Corrosion behavior of AA6061 alloy and AA6061-5wt.%TiB2in-situ metal matrix composite processed through equal channel angular pressing

Purpose This study aims to report the corrosion behavior of AA6061 alloy, and AA6061–5 Wt.%TiB2in situ metal matrix composite prepared by stir-casting method followed by further processing by equal channel angular pressing (ECAP). Design/methodology/approach An optical microscope, a scanning electron microscope and a high-resolution transmission electron microscope was observed. Open circuit potential (OCP) tests, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements were conducted in a 3.5 Wt.% NaCl solution at room temperature for each sample. Findings The corrosion rate of the AA6061 alloy decreased from 390 µm/year in the annealed samples to 3 µm/year following 10 passes of ECAP. The corrosion rate of AA6061–TiB2 composites decreased from 203 µm/year in the annealed samples to 126 µm/year after 10 passes of ECAP. The polarization resistance (Rp) value of AA6061 increased to 53,232 kO·cm² following 10 passes of ECAP, significantly higher than the 2,822.5 kO·cm² observed in the annealed sample. Likewise, the Rp value of AA6061–TiB2 composites increased to 2,143.5 kO·cm² after 10 passes, as opposed to the 1,551.9 kO·cm² measured in the annealed sample. Originality/value OCP tests, EIS and potentiodynamic polarization measurements were conducted in a 3.5 Wt.% NaCl solution at room temperature. Ultrafine grain structures were obtained after 10 passes of ECAP, which exhibited better corrosion resistance compared to annealed samples under both conditions. For both materials, an increase in OCP values and a decrease in the corrosion rate from annealed samples after 10 passes of ECAP was seen. In addition, Rp values for AA6061 alloy and AA6061–5 Wt.% TiB2 increased from annealed sample to after 10 passes.