Influence of core–shell intermetallic on dynamic recrystallization and processing maps of novel Al-Cu-Ni composite through Arrhenius and artificial neural network (ANN) models.

A novel Al-Cu-Ni composite, featuring Ni-Al3Ni2/Al3Ni core–shell intermetallics within its matrix produced via powder metallurgy, was subjected to isothermal compression tests at different conditions so as to garner an insight into its hot deformation behaviour. These experiments were conducted from 300 to 500 °C, with strain rates varying from 0.0001 s−1 to 0.1 s−1. It is found that the flow stress is influenced by both strain rate and temperature. As the deformation temperature reduced or the strain rates increased, the peak stress level increased. To characterize the flow stress of the composite, a sine-hyperbolic constitutive equation was developed and the calculated value of activation energy (234 kJ/mol) was substantially higher than that for the self-diffusion of pure Al. Subsequently, the strain-compensated Arrhenius model and the artificial neural network (ANN) model were developed to predict the composite flow behaviour. With a lower average absolute relative error of 2.266%, a smaller root means square error of 0.668 MPa, and a higher correlation coefficient of 0.999 than the Strain-compensated Arrhenius model, the ANN model is more predictable. The processing maps show that the ideal hot working conditions for the composite are between 400 and 500 °C, with strain rates between 0.0001 s−1 and 0.01 s−1 with an efficiency of 37%. The uneven distribution in the shape and size of Core–shell/Al3Ni intermetallic compounds influenced the flow stress curves, leading to dynamic recrystallization (DRX), followed by partial dynamic recovery (DRV), and ultimately strain hardening at 0.01 s−1 & 0.1 s−1. The occurrence of recrystallization and recovery up to a specific strain followed by strain hardening at all the deformation temperatures is a rare phenomenon and has been attributed to the structure and composition of core–shell intermetallics. The occurrence of work hardening at higher strains throughout the operational range of temperatures imparts greater reliability to structural components. [ABSTRACT FROM AUTHOR]