In-situ neutron diffraction studies of the pseudoelastic-like behaviour of hydrostatically extruded Mg-Al-Zn alloy

摘要

In-situ neutron diffraction has been used to study the pseudoelastic-like behaviour of hydrostatically extruded AZ31 magnesium alloy during stress-strain cycles in compression and tension along the extrusion direction. It has been confirmed that the activation of reversal twinning processes during unloading is responsible for the macroscopically observed hysteresis effect. Moreover, neutron diffraction data reveals the existence of high tensile stresses in grains which have just experienced significant twinning activity prior to the start of the unload cycle. It is thus proposed that this tensile stresses provides the necessary driving force for the activation of untwinning in already twinned grains.