Elucidation of formation and transformation mechanisms of Ca-rich Laves phase in Mg-Al-Ca-Mn alloys
Jiehua Li, Xuyang Zhou, Andrew Breen, Zirong Peng, Jing Su, Philipp Kürnsteiner, María Jazmin Duarte, Marta Lipińska Chwałek, Hui‐Yuan Wang, David Holec, Joachim Mayer, Gerhard Dehm
Abstract
The formation of thermally stable intermetallic phases plays a key role to enable high temperature applications for Mg alloys. In the ductile Mg-Al-Ca system, Ca-rich Laves phases are expected to be crucial for improving high temperature mechanical properties. However, the formation mechanisms of Ca-rich Laves phases are still unresolved. Here, we report atomic-scale experiments and simulations on transformation of Ca-rich Laves phases and formation of Ca-rich clusters as well as Ca-segregation behaviour in Mg-Al-Ca-Mn alloys in three conditions: as-cast, homogenised (500 °C, 20 h), and rolled (350 °C). The formation mechanisms of C36 Laves phase and Mg-rich particles (eutectic Mg) within C36 Laves phase were attributed to a divorced eutectic reaction. The transformation mechanisms from C36 to C15 Laves phase were revealed and discussed in terms of Mg out-diffusion of C36 Laves phase, the partitioning of Al into C36 Laves phase and the change of stacking sequences. The combined atomic-scale experimental and simulation investigation reveals complex interactions among various Ca-rich Laves phases in Mg-Al-Ca-Mn alloys.