Large strain hardening of magnesium containing in situ nanoparticles

Zhongxue Feng,Xianhua Chen,Yuming Chen,Yuhua Zhang,Jun Tan,Jianbo Li,Fusheng Pan,Yiming Chen,Kaihong Zheng

doi:10.1515/ntrev-2021-0074

Abstract

Abstract In this work, in situ magnesium-based composite composed of nanoscale magnesium oxide (MgO), prepared by spark plasma sintering, shows significant plasticity and high strain hardening. During the strain-hardening stage, the incremental work-hardening exponent shows drastic fluctuations due to the pile-up and release of dislocations. The dislocation pile-up at the interface makes it possible to form dislocation cells. Mixed dislocations can be generated within the cells surrounding the MgO particles, which can interact with the stress field and effectively hinder the movement of dislocations, leading to an increase in dislocation density. What is more, grain boundaries have higher elastic modulus and hardness, which may lead to the appearance of microcracks and eventually intergranular fractures. Our results may shed some light on understanding the role of MgO particles in influencing the mechanical properties of Mg alloys and Mg-based composites, especially in work hardening.

Highlights

IntroductionThe phenomenon of strain hardening (or work hardening) refers to the increase in strength and hardness of a material during plastic deformation below the recrystallization temperature (e.g., room temperature), preventing further deformation of the material [1]
The phenomenon of strain hardening refers to the increase in strength and hardness of a material during plastic deformation below the recrystallization temperature, preventing further deformation of the material [1]
One can see that a very small amount of magnesium oxide (MgO) particles is retained within the original Mg powder, as exemplified by some areas marked with red dotted lines

Summary

Introduction

The phenomenon of strain hardening (or work hardening) refers to the increase in strength and hardness of a material during plastic deformation below the recrystallization temperature (e.g., room temperature), preventing further deformation of the material [1]. It improves the strength [3,4], hardness [5,6], and wear resistance [7,8] of metals, which is important for pure metals and certain alloys that cannot be strengthened by heat treatment [9]. Strain hardening can hinder the continued development of plastic deformation and greatly improve the safety of the components. Magnesium (Mg) alloys and their composites are being actively developed and used in many applications, including the automobile, aircraft, and aerospace industries, because of their potential to improve energy efficiency [10,11,12]. Mg-based composites have been developed to improve the engineering strength and elastic modulus by adding reinforcements such as MgO [17], Al2O3 [18,19,20], SiC [21], TiC [22,23], This work is licensed under the Creative Commons Attribution 4.0

Results

Discussion

Conclusion