Plastic deformation behavior of 10H-type synchronized LPSO phase in a Mg–Zn–Y system

Abstract We recently succeeded in fabricating a new type of synchronized long-period stacking ordered (LPSO) phase crystal with the 10H crystal structure in the Mg–Zn–Y system. In the 10H LPSO phase, the long-range order of the Zn/Y-enriched L12-like cluster was more significantly developed than that in the previously reported 18R LPSO phases in the Zn/Y concentrated layer. As the operative deformation mode in the 10H phase, (0001) 2 ¯ 0> basal slip was found to predominate. In addition, the formation of deformation kink bands was confirmed under conditions in which the operation of basal slip was macroscopically hindered. These features were similar to those observed in the 18R phase, but some differences were also observed in the deformation behavior owing to the development of in-plane ordering in the Zn/Y concentrated layers. The formation of a deformation kink band was localized in the deformation of the 10H crystal, and the localization of the kink-band formation was more enhanced in a specimen annealed at 500 °C for 24 h, in which the long-range order of the L12-like cluster was pronounced. In addition, the operation of nonbasal slip was hindered in 10H crystals during deformation at high temperatures. The localization of kink-band formation and the prohibition of nonbasal slip induced the frequent formation of microcracks during the deformation of the 10H crystal, which led to fracture in the early stage of deformation. Experimental results demonstrated that the development of in-plane ordering of the L12-like cluster in the Zn/Y concentrated layer is significantly detrimental to the ductility of the synchronized LPSO phase.