An Analysis of the Tensile Deformation Behavior of Commercial Die-Cast Magnesium-Aluminum-Based Alloys

Magnesium and its alloys have a complex progression of deformation mechanisms due to the hexagonal closed-packed crystal structure. Magnesium undergoes a series of different deformation modes as stress increases. The deformation behavior is marked by the commencement of elastic (Stage I), followed by < a > basal slip and twinning (Stage II), < a > prismatic slip (Stage III) and finally < c + a > pyramidal slip (Stage IV). In this study, the deformation behavior of a range of commercial die-cast magnesium-aluminum-based alloys are analyzed. Four distinct stages of strain hardening can be seen in the tensile stress-strain curve and these are modeled according to the assumption that they correspond to the four deformation mechanisms. It is shown that both Stages I and III can be described by a linear equation while Stages II and IV follow a power-law relationship and fitted with Hollomon's equation. A semi-empirical equation is proposed to model the entire stress-strain curve, which provides a simple way to understand the deformation of magnesium alloys and points towards better methods of modeling magnesium alloy behavior in part design.