Characterisation of precipitates formed in high-pressure torsion treated Mg-3.4at.%Zn alloy

TL;DR

This study investigates the microstructural evolution of a Mg-3.4at.%Zn alloy subjected to high-pressure torsion, revealing the formation and stability of nanoscale precipitates without heat treatment.

Contribution

It provides detailed characterization of precipitate types, sizes, and distributions in a Mg-Zn alloy deformed by HPT, highlighting the microstructural stability during severe plastic deformation.

Findings

Precipitates with radii 2.5-20 nm form after one rotation.

Little change in precipitate size or volume fraction after 20 rotations.

Different Mg-Zn phases identified at various deformation stages.

Abstract

Microstructural analysis of a Mg-Zn alloy deformed at room temperature by high-pressure torsion (HPT) indicates that fine-scale precipitation occurs even without post-deformation heat treatment. Small-angle X-ray scattering detects precipitates with radii between 2.5-20 nm after one rotation, with little increase in particle size or volume fraction after 20 rotations. High resolution electron micrographs identify grain boundary precipitates of monoclinic Mg$_4$Zn$_7$ phase after three rotations and MgZn$_2$ after 20 rotations.