On the twinning shear of {101¯2} twins in magnesium - Experimental determination and formal description

Specifically oriented Mg single crystals, aligned for c-axis extension, were deformed in channel-die plane strain compression in order to form {101¯2} extension twins. The amount of twinning shear for {101¯2} twins was determined directly from the deflection of marker lines to be s=0.126, in excellent agreement with the theoretical value. The twinning shear was discussed with respect to the shear-coupled grain boundary migration by analyzing the formal dislocation content of {101¯2} twin boundaries. The respective boundary migration - shear coupling factor is proposed to result from a combination of two elementary coupling modes, 〈101¯0〉 and [0001].

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