Microstructure Features and Superplasticity of Extruded, Rolled and SPD-Processed Magnesium Alloys: A Short Review

Abdul Malik,Umer Masood Chaudry,Kotiba Hamad,Tea-Sung Jun

doi:10.3390/met11111766

Abdul Malik, Umer Masood Chaudry + Show 2 more

Open Access

https://doi.org/10.3390/met11111766

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Abstract

In this study, an overview of microstructure features such as grain size, grain structure, texture and its impact on strain rate sensitivity, strain hardening index, activation energy and thermal stability for achieving superplasticity of Mg alloys are presented. The deformation behavior under different strain rates and temperatures was also elaborated. For high elongation to fracture grain boundary sliding, grain boundary diffusion is the dominant deformation mechanism. In contrast, for low-temperature and high strain rate superplasticity, grain boundary sliding and solute drag creep mechanism or viscous glide dislocation followed by GBS are the dominant deformations. In addition, the results of different studies were compared, and optimal strain rate and temperature were diagnosed for achieving excellent high strain rate superplasticity.

Highlights

The use of lightweight materials is a convenient way to reduce carbon dioxide emissions and increase fuel efficiency so that their use can be enhanced as a structural material in automobile and military industries
Critical resolved shear stresses (CRSS) are very low for basal slip and extension twinning in early stages of deformation [12], whilst the CRSS of non-basal slip is significantly reduced under high-temperature loading; multiple slip activity and no twinning activity are beneficial for the smooth processing of Mg alloys [13]
The grain size ≥10 μm is not recommended for excellent superplasticity;

Summary

Introduction

The use of lightweight materials is a convenient way to reduce carbon dioxide emissions and increase fuel efficiency so that their use can be enhanced as a structural material in automobile and military industries. Superplasticity is intriguing for industrial and academic development due to the ability to manufacture complicated components It can produce uniform elongation without strain hardening, pre-mature failure and necking. The most important parameters for superplasticity, strain rate sensitivity (m-value) and hardening index (n-value) are highly dependent on the aforementioned parameters These feathers are very significant for achieving the superplasticity of Mg alloys. High strain rate and low temperature are the requirements for industrial manufacturing, which can save time and energy. This low temperature and high strain rate can change the rate of deformation, and change the m-value, Q-value and n-value. This study sheds light on the microstructure features of different fabricated Mg alloys and their response/deformation to facilitate superplasticity

Grain Size and m-Value

Elongation to Fracture and Deformation Mechanism

Texture Evolution

Findings

Conclusions