Twin pattern evolution in a fine-grained Mg alloy subjected to indentation

A Vickers diamond pyramid indenter was impressed on a fine-grained polycrystalline Mg-3Al-1Zn alloy. Serial polishing in combination with quasi-in-situ electron backscatter diffraction (EBSD) examinations revealed the presence and the 3D spatial distributions of {10-12} extension twins around the indent. Twin chains and completely twinned areas were found in some regions close to the indent. A model of twin pattern evolution around the indent was proposed based on the experimental observations and local strain accommodation analysis.