Isothermal forging of metal matrix composites: Recrystallization behaviour by means of deformation efficiency

The hot forming behaviour of 2618 aluminium alloy reinforced with 20% of Al2O3 particles have been studied by employing both “processing maps” and microstructural observations. The material under investigations was deformed by torsion in the temperature and strain rate ranges 350–500 °C and 10−3–10 s−1, respectively. The deformation efficiency was calculated by strain rate sensitivity (m) values obtained by hot torsion tests. The material showed a regime of dynamic recrystallization in the ranges 450–500 °C and 10−2–10−1 s−1 corresponding to the higher values of efficiency. The material was characterized by employing optical and electron microscopy (SEM, TEM) to evaluate the microstructural transformations and instability phenomena.