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

摘要

The hot forming behaviour of 2618 aluminium alloy reinforced with 20 percent of Al_2O_3 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 deg C and 10~(-3)-10 s~(-1), respectively. The deformation efficiency was calculated by strain rate sensitivity {in} values obtained by hot torsion tests. The material showed a regime of dynamic recrystallization in the ranges 450-500 deg C and 10-10~(-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.