In situ investigation of the activation characteristics of basal slip systems in Mg-Y-Nd-Zr-Gd alloy: From the perspective of Schmid's law and plasticity transfer

• In situ SEM/EBSD experiments combined with a multilevel strategy enabled precise identification of coplanar basal slip systems. • Half of the activated basal slip systems exhibited non-Schmid behavior. • Predicting basal slip activation requires considering both the Schmid factor and plastic transfer capacity. In situ SEM/EBSD characterization was utilized to monitor dislocation activation during the plastic deformation of the Mg-Y-Nd-Zr-Gd alloy. Through a correlative analysis of slip traces and crystal rotation, the active basal slip systems were precisely identified. It was initially observed that grains dominated by basal slip exhibit a coexistence of multiple basal slip systems during plastic deformation. Furthermore, the activated basal slip systems were found to exhibit pronounced non-Schmid behavior. Subsequently, through specific case analyses and comprehensive statistical evaluation, the limitations of the Schmid factor in predicting the activation of basal slip systems in the Mg-Y-Nd-Zr-Gd alloy were objectively assessed. It was further highlighted that the plastic transfer significantly promotes the activation of basal slip systems, particularly for individuals with low Schmid factors.