Profuse slip transmission across twin boundaries in magnesium

Abstract

In-situ SEM simple shear tests were performed on magnesium bicrystals of random misorientations at room temperature and 150 °C. {101¯2} extension twins nucleated at the grain boundaries and grew with increasing strain. Rectilinear slip traces appeared in the grain interior of the bicrystal which corresponded to basal slip. By deflection at twin boundaries, these slip lines readily continued through the twins. Besides slip traces due to basal slip, additional slip lines were observed inside twins at 150 °C that evidenced the activation of non-basal slip. Supplemental tests were performed on single crystals, in which twinning/detwinning via migration of twin boundaries was observed. The obtained results are discussed with respect to direct and indirect slip transfer across {101¯2} twin boundaries, the transmutation of 〈a〉 into 〈c+a〉 dislocations and the activation of first-order pyramidal slip as a result of slip-twin interaction.