A novel basal precipitate plate derived from a Mg2Ca Laves phase in a Mg-Nd-Ca alloy

The basal precipitate is a category of the key precipitation strengthening phase in Mg-based alloys. In this study, a novel basal plate designated as. gamma''' in a Mg-Nd-Ca alloy is investigated by high-angle annular dark-field scanning transmission electron microscopy. It is found that the. gamma''' phase has a hexagonal structure (a = 0.604 nm and c = 1.008 nm) and a ternary composition. Structurally, it can be described as an alternate arrangement of the. gamma '' plate and the (0001) monolayer atomic layer. Particularly, different with the conventional. gamma '' phase, the gamma''' phase has an extraordinary origin and is proved to be derived from a Mg2Ca C14 Laves phase, which is formed earlier in beta(1) chains in the shape of bubble. This study contributes to provide a new understanding of the formation mechanism of gamma-type basal precipitates. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study investigates a novel basal plate designated as gamma''' in a Mg-Nd-Ca alloy, revealing its hexagonal structure, ternary composition, and extraordinary origin derived from a Mg2Ca C14 Laves phase. This research contributes to a new understanding of the formation mechanism of gamma-type basal precipitates.