Response surface methodology and process optimization of spark plasma sintered parameters of Ti₂₀Al₂₀Cr₅Nb₅Ni₁₉Cu₁₂Co₁₉ high entropy alloy

Study was carried out on the effect of milling and sintering process parameters on the relative density and microhardness property of a septenary non-equiatomic Ti₂₀Al₂₀Cr₅Nb₅Ni₁₉Cu₁₂Co₁₉ high entropy alloy fabricated via spark plasma sintering (SPS) process at 100 °C/min constant heating rate, 5 min dwell time, and at a pressure of 50 MPa. A predictive model was developed through response surface methodology (RSM) using the SPS sintering temperature (ST) and milling time (MT) as the process variables. In order to reduce the number of experimental runs, the design of experiment (DOE) technique was used, to eventually avoid the trial-and-error process associated with conventional experimental procedures. The user-defined design (UDD) of the RSM was used to forecast the optimal operating parameters, and the outcome was validated by experiments. Findings indicate that MT and ST are important in achieving high densification, which leads to high densification and mechanical properties. Optimization model shows that, at MT of 7.20115 h and ST of 899.742 °C, desirable responses of 99.9 % relative density, percentage porosity of 0.0999994 % and a micro-hardness value of 835.21 HV can be attained.