High Ductility with a Homogeneous Microstructure of a Mg–Al–Zn Alloy Prepared by Cyclic Expansion Extrusion with an Asymmetrical Extrusion Cavity

Zhaoming Yan,Jie Zheng,Qiang Wang,Yong Xue,Zhimin Zhang,Jiaxuan Zhu

doi:10.3390/met10081102

Abstract

In the current work, cyclic expansion extrusion with an asymmetrical extrusion cavity (CEE-AEC), as a relatively novel severe plastic deformation method, was applied to fabricate an AZ31B magnesium alloy plate with a size of 50 × 100 × 220 mm, and the resultant microstructure, texture development, and mechanical properties were systematically investigated. A refined and homogeneous grain structure was achieved after three passes of deformation due to dynamic recrystallization. The grain refinement degree in comparison to as-cast alloys was more than ~96%. With the increasing number of CEE-AEC passes, a basal inclination texture was gradually formed, with the basal planes inclined ~45° from the transverse direction to the extrusion direction, which could be attributed to the introduction of an asymmetrical extrusion cavity that led to an increasing Schmid factor for the activation of basal <a> slip systems. The comprehensive mechanical properties were improved by successive multi-passes of CEE-AEC processing, especially due to the ductility reaching to 30.0 ± 1.3% after three passes of deformation. The competition between the grain refinement and texture modification were the main strengthening mechanisms.

Highlights

Magnesium (Mg) and its alloys, which have the advantages of a low density, a high specific strength, easy recyclability, etc., have broad application prospects in national defense, aerospace, automobile, and 3C communication [1,2,3,4]
Grain refinement and texture modification have been proven to be effective ways to improve the ductility of Mg alloys [1,7]
We propose a novel severe plastic deformation (SPD) method entitled cyclic expansion extrusion with an asymmetrical extrusion cavity (CEE-AEC) to fabricate thick plate 50 × 100 × 220 mm

Summary

Introduction

Magnesium (Mg) and its alloys, which have the advantages of a low density, a high specific strength, easy recyclability, etc., have broad application prospects in national defense, aerospace, automobile, and 3C communication [1,2,3,4]. Due to their poor strength and low ductility at room temperature, the development and application of Mg alloys are still limited [5]. Severe plastic deformation (SPD) has attracted more and more attention in the Mg alloy field, because it is believed to be a practical and promising technology to prepare high strength/toughness Mg alloys by modifying their microstructures and textures.

Results

Discussion

Conclusion