抄録
We have examined the plastic deformation behavior of Mg12ZnY phase having the so-called "chemical and structural modulations synchronized long-period stacking ordered (LPSO) structure". In this presentation the variation in mechanical properties of the LPSO-phase depending on their stacking sequence is discussed. A 14H-typed LPSO-phase crystal was fabricated by annealing a directionally solidified (DS) crystal with a 18R-typed LPSO-structure at 525 ℃ for 3 days, and the temperature dependence and orientation dependence of the yield stress were examined via compression tests. (0001)<1120> basal slip was identified as a dominant deformation mode, and deformation kink bands were formed under compression in the case of suppression of basal slip motion. It was found that the deformation mechanism of the 14H-typed LPSO-phase is almost similar to that of the 18R-typed LPSO-phase, irrespective of their stacking sequences. The existence of the LPSO-phase in Mg-alloy strongly enhances the refinement of Mg matrix grains during extrusion, which leads to a large increase in yield stress through the Hall-Petch relationship. In addition, the LPSO-phases are aligned along the direction of extrusion in the alloy during the extrusion process, and they act as hardening phases, being roughly coordinated with the short fiber-reinforcement mechanism.
