Characteristics of the contraction twins formed close to the fracture surface in Mg–3Al–1Zn alloy deformed in tension

Characteristics of the “contraction” twins, formed close to the fracture surface in Mg–3Al–1Zn alloy deformed in tension approximately perpendicular to the grain c-axes, are investigated using transmission electron microscopy. The grain c  -axis contractions were largely accommodated by {101¯1}–{101¯2} double-twins in a variant characterized by 38°〈12¯10〉 twin/matrix misorientation in conjunction with dislocation slip. A possible interpretation of the observed preference for this variant formation is given and some crystal plasticity modelling is performed to elucidate the matter.