Constitutive Modeling and Hot Deformation Behavior of Duplex Structured Mg-Li-Al-Sr Alloy

Hot deformation behavior of an as-extruded duplex structured Mg-9Li-3Al-2.5Sr alloy is investigated via hot compression tests conducted at 200-350 °C with strain rate of 0.001-1 s−1. The flow behavior of Mg-9Li-3Al-2.5Sr alloy can be described accurately by hyperbolic sine constitutive equation and the average activation energy for deformation is calculated as 143.5 kJ/mol. Based on a dynamic materials model, the processing maps of Mg-9Li-3Al-2.5Sr alloy which describe the variation of power dissipation efficiency are constructed as a function of temperature and strain rate. The processing maps exhibit an area of discontinuous dynamic recrystallization occurring at 280-300°C with strain rate of 0.001-0.01 s−1, which corresponds to the optimum hot working conditions.