Structures of Precipitates in Mg-RE (RE: Rare Earth Metals) Alloys Studied by HAADF-STEM and HRTEM

Abstract

Mg-based alloys containing rare earth elements show remarkable precipitation hardening by aging of supersaturated solid solutions at low temperatures, and so examinations about microstructures of precipitates and precipitation process have been important subjects by TEM and HRTEM. We have studied structures of fine precipitates in Mg-Gd, Mg-Y and Mg-Gd-Zn alloys by the combination of HRTEM and HAADF-STEM, and obtained some valuable results, which can not be accomplished by TEM and HRTEM. In this paper, we review recent results about crystal structures and microstructures of fine coherent precipitates and GP-zones, and demonstrate the power of HAADF-STEM for the examination of fine precipitates in Mg-RE alloys.