GeSbTe　alloys　have　the　ability　of　rapidly　transforming　between　amorphous　and　crystalline　phases.　Therefore,　they　can　be　used　in　the　non-volatile　phase　change　memory.　Recently,　a　vacancy-ordered　cubic　Ge2Sb2Te5　(VOC　GST)　phase　change　material　where　the　vacancies　are　highly　ordered　in　the　(111)　plane,　has　been　experimentally　demonstrated　by　STEM.　However,　studies　are　mainly　on　the　structural　characterization,　rather　than　on　the　phase　change　behavior　and　possible　applications　of　the　VOC　GST.　Here,　using　first-principles　molecular　dynamic　simulations,　we　study　the　melt-quenched　amorphization　process　and　its　possible　applications.　We　find　that　the　VOC　GST　exhibits　a　quasi-two-dimensional　amorphization　process　that　is　triggered　by　the　diffusion　of　Ge　atoms　but　not　others.　A　partial　amorphous　(P-amor)　phase　is　obtained,　which　can　act　as　an　intermediate　state　between　the　pure　amorphous　and　pure　crystalline　phases　for　possible　ternary-state　data　storage.　(C)　2017　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.