Tension-compression-tension tertiary twins in coarse-grained polycrystalline pure magnesium at room temperature

Using electron backscatter diffraction, the microstructural features of tension–compression–tension (T–C–T) tertiary twins are studied in coarse-grained pure polycrystalline magnesium subjected to monotonic compression along the extrusion direction in ambient air. T–C–T tertiary twins are developed due to the formation of a compression–tension double twin inside a primary tension twin. All the observed T–C–T twin variants are of T_iC_jT_j type. T_iC_i+1T_i+1 (or T_iC_i?1T_i?1) variants are observed more frequently than T_iC_i+2T_i+2 (or T_iC_i?2T_i?2) variants. The number of tertiary twin lamellae increases with the applied compressive strain.