Hot isotherm compression tests were performed in temperature range of 350–500 °C and at strain rates of 0.0005 to 0.5 s1 for Al6061 alloy reinforced with alumina nanoparticles. Effect of deformation parameters and optimal conditions for hot working this nanocomposite were comprehended thoroughly via hot working data analyses, electron microscopy images, and X-ray diffractograms. The results indicated the severity of hot deformation process and an increase in the activation energy to 320 kJ/mol due to the addition of nanoparticles. Dynamic recovery (DRV) was considered as the individual determinative softening mechanism during hot deformation of this nanocomposite, and no sign of dynamic recrystallization (DRX) phenomenon observed in the same domain. The unstable region occurred at high strain rates and temperature range of 350–500 °C accompanied with happening drastic defects such as shear bands and cracks. Furthermore, the value of both critical strain and critical stress increased with increasing the strain rate and alumina addition. On the other hand, increasing the temperature decreased the value of critical strain and facilitated the initiation of softening mechanisms.

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