Grain-scale creep processes in Mg–Al–Ca base alloys: Implications for alloy design

Grain-scale creep straining processes in die-cast and permanent-mold-cast Mg–Al–Ca alloys have been studied. High-temperature strain mapping with electron backscattered diffraction analysis reveals favorably oriented grains deforming preferentially during creep. Displacements of microstructural-scale markers applied along grain boundaries and within grain interiors demonstrate no significant contribution of grain boundary sliding to creep. Creep rates at 175 °C display an inverse dependence on grain size, with fine-grained die-cast material possessing the highest creep resistance. Implications for the design of future alloys are discussed.