The effect of strontium in plasticity of magnesium alloys

The objective of this article is to quantify relationships between microstructural changes and the room temperature mechanical behavior of novel extruded Mg-Al-Zn-Sr alloys. To this aim, targeted mechanical testing coupled with full-field strain measurements and simultaneous acoustic emission recordings is further combined with grain-scale observations. To date, the precise effect of alloying elements on the plasticity of Mg alloys is still largely unknown. Strontium in wrought Mg alloys has already been shown to reduce grain size and texture anisotropy, as well as improve their creep resistance, replicating the effects of rare earth elements. To further investigate the effects of Sr on the mechanical properties and plasticity of Mg alloys compression tests were performed and were coupled with nondestructive measurements provided by digital image correlation and acoustic emission monitoring. The results presented herein demonstrate the effect of the extrusion temperature and provide direct correlations between Sr content and bulk mechanical properties, overall plasticity and texture evolution in these novel alloys. Furthermore, the addition of Sr was found to be related to distinct strain localizations near yielding, which were linked to twinning activity, providing in this way a route for quantitative control of their microstructural design.