The interrupted properties of an extruded Mg alloy

The current paper investigates the effect of {101¯2} extension twins identified by using electron backscattered diffraction on the interrupted properties of an extruded Mg–3Al–1Zn (AZ31) alloy. Compressive and recompressive tests are conducted along extrusion direction (ED). It is discovered that the yield strength of recompression is enhanced due to grain refinement by {101¯2} extension twins. The reinforcement effect of {101¯2} extension twins on the yield stress of recompression is mainly reflected at the stage of small deformation while the improvement of yield strength is mainly attributed to the pile-up and intersection of dislocations as large deformation occurs. Furthermore, the yield stress of recompression is identical to the interrupted stress of precompression. In situ observation reveals that some twins generated in precompression could also become thicker in the following recompression.

► The reinforcement effect of {101¯2} twins on yield stress is reflected at low deformation.
► The recompressive yield stress equals to the stress when it is unloaded.
► The stress–strain curve of recompression seems like that without interruption.
► Twins generated in precompression could become thicker in recompression.