Nucleation of recrystallized magnesium grains over quasicrystalline phase during severe plastic deformation of a Mg-Zn-Y alloy at room temperature

We show by high pressure torsion at room temperature and transmission electron microscopy that nucleation of recrystallized alpha-Mg grains occurs preferentially over quasicrystalline i-phase particles at an early stage of recrystallization in a Mg-3.0Zn-0.5Y (at%) alloy. alpha-Mg grains nucleated on i-phase surfaces by torsional rotation N = 1/2 (at 5GPa pressure), and show definite orientation relationships with the i-phase. These orientation relationships are asymmetrical variations of those reported for as-cast and extruded alloys. The nucleated grains show a planar interface with the i-phase and are often faceted as they grow into a yet unrecrystallized matrix. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.