Isometric Tilt Grain Boundaries and Solute Segregation in a Deformed Mg–Zn–Ca Alloy

Abstract

Solute segregation to grain boundaries is an essential phenomenon that affects multiple mechanical properties of magnesium alloys . In this work, the deformed microstructure in a Mg–Zn–Ca alloy that was compressed at room temperature has been examined by bright-field and high-angle annular dark-field scanning transmission electron microscopy. Domains made of nanograins have been observed in some local areas. These domains exhibit strong texture and most of the nanograins oriented with their $\left\langle {11\bar{2}0} \right\rangle_{\alpha }$ being paralleled to each other, which is similar to those reported in the Mg–Gd alloy. The grain boundaries of these nanograins involve many isometric tilt boundaries containing twin boundaries. Segregation of Zn/Ca atoms occurs in these tilt boundaries in the cold deformed sample. The segregation forms unique and chemically ordered patterns specific to tilt boundaries.