Investigating the effects of processing parameters on microstructure and mechanical properties of Ni-Al-Co-Cr-Cu-Mn-Ti high entropy alloys: A response surface methodology approach

High-entropy alloys (HEAs) have attracted significant attention due to their unique properties, but their development is hindered by the vast compositional space requiring extensive experimentation. This study introduces an optimization of processing parameters for a novel septenary equiatomic Ni-Al-Co-Cr-Cu-Mn-Ti HEA using user-defined design response surface methodology (UDD-RSM). The methodology focused on mechanical alloying and spark plasma sintering (SPS) techniques, examining the influence of milling time (MT) and sintering temperature (ST) on the microstructure, mechanical properties including relative density, porosity, and microhardness. SEM-EDS analysis identified a dominant CoNiCrCuMnTi phase alongside secondary (CuNiMn and CrCo) phases, with the optimized processing parameters predicting a relative density of 99.83 % and a microhardness of 742.019 HV at a sintering temperature of 896.009 °C for 11.9 h. The study not only demonstrates the utility of UDD-RSM in efficiently navigating the parameter space for HEA development but also contributes to the broader understanding of the relationship between processing conditions and the resulting material properties of HEAs.