Interphase boundary segregation of silver and enhanced precipitation of Mg17Al12 Phase in a Mg-Al-Sn-Ag alloy

Aging-hardening response of Mg-7Al-2Sn (wt%) alloy can be remarkably accelerated by a small addition of silver (Ag). Using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with high resolution energy dispersive X-ray spectroscopy (EDS) mapping, for the first time, segregation of solute atoms (Ag in this case) was observed at the interphase boundary between continuous Mg17Al12 precipitate and magnesium matrix in Mg-7Al-2Sn alloy with 0.7 wt% Ag addition. Substantial size refinement and increased number density of Mg17Al12 precipitates may be responsible for the enhanced aging-hardening response in Mg-7Al-2Sn alloy with Ag addition. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.