• The hot deformation behavior of Al–12Ce–0.4Sc alloy is characterized by dynamic recovery and slight flow softening, with dynamic strain aging occurring at 400–450°C and strain rates of 0.01–0.1 s−1.
• Two constitutive models—strain-compensated Arrhenius and logistic regression—were developed, with average stress exponent (n) of 14.25 and apparent activation energy (Q) of 209.58 kJ·mol−1.
• The optimal hot-working condition is identified as 400°C and 1 s−1, achieving a maximum power dissipation efficiency of 22%.
• Unstable domains in the processing map are linked to fracture of pro-eutectic Al11Ce3 intermetallics and interfacial cracks, providing critical insights for defect-free processing.