Hot compression behavior of the AZ91 magnesium alloy produced by high pressure die casting

The hot deformation behavior of a Mg–9Al–1Zn alloy produced by high pressure die casting has been investigated by means of compression tests in the temperature and strain rate ranges of 125–300 °C and 1.6 × 10−5 to 10−1 s−1, respectively. The samples were deformed in the high pressure die casting state or after an exposure at 415 °C for 2 h to evaluate any different response to deformation. A premature fracture at 45° respect to the compression axis was observed in samples strained at low temperatures and high strain rates. The stress–strain curves are explained in terms of microstructure evolution, with emphasis on the eutectic phase and on dynamic precipitation phenomena occurring at low and high temperature of deformation. Constitutive parameters were evaluated in order to better understand the microstructure evolution. Light and scanning electron microscopy have been performed to correlate the microstructure to the deformation parameters in all the tested conditions.