In this study, three non-linear mathematical models were developed using a central composite design for the prediction of heat treatment effects on Vickers micro hardness (HV), Rockwell hardness (RHN), and electrical conductivity (%IACS) of nano Al2O3 reinforced Al composite fabricated by a two-step stir casting method. As per the investigation, both process variables of heat treatments such as solution temperature and aging temperature considerably influence the changes in hardness and electrical conductivity of Al composite. For the two-way interaction analysis of variance test, the R2 values for HV, RHN, and %IACS were 89.29%, 96.23%, and 91.50%, respectively, with a 95% confidence level and 5% significance level. As per the regression equation, the optimized process variables of heat treatment such as solution temperature and aging temperatures are 531.4280C and 1800C which can provide an improvement of 23.15%, 33.57%, and 9.57% respectively for HV, RHN, and %IACS in contrast to their as-cast conditions., Here, the maximum error (%) measured between experimental and prediction are respectively 3.52%, 6.09%, and 2.69%. The microstructure reveals an almost uniform distribution of nano Al2O3 in Al composite with fewer agglomeration. The formation of intermetallic compounds at different heat treatment processes identified in SEM impacted the changes in the electro-mechanical properties of fabricated Al composite.
