A kind of sandwich-combined precipitate formed in a duplex-aged Mg-Gd-Y alloy

摘要

A kind of needle-like sandwich-combined precipitation product (denoted as g) was found to be formed concurrently with the equilibrium beta-phase in a Mg-Gd-Y alloy subjected to duplex aging at 200 degrees C and 250 degrees C, respectively, and its structure was characterized by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) technique. It had been clearly revealed that the eta-precipitate consists of a new base-centered orthogonal (BCO) precipitate as a long core (B) which is invariably sandwiched by the face-centered cubic (FCC) Gd(Y) solute precipitate platelets (F) as surface-shells. The orientation relationships involved with the unique F-B-F sandwiched precipitation for the g constructing in the Mg matrix were determined to be 001 F//; 001(B); {010}(F)//{010}(B) and 100(F)// 0001(Mg), {010}(F)//{10 (1) over bar 0}(Mg), respectively. (c) 2020 Elsevier B.V. All rights reserved.