Hot Compression Deformation and Activation Energy of Nanohybrid-Reinforced AZ80 Magnesium Matrix Composite

Houyi Li,Mingyang Zhou,Lingling Fan,Yong Chen,Youlong Zhou,Kuan Jiang

doi:10.3390/met10010119

Abstract

The hot deformation test of the nano silicon carbide (nano-SiC) and carbon nano tubes (CNT) hybrid-reinforced AZ80 matrix composite was performed at compression temperatures of 300–450 °C and strain rates of 0.0001–1 s−1. It could be observed that the flow stress of the nanocomposite rose with the reduction of deformation temperature and the increase of strain rate. The hot deformation behaviors of the composite could be described by the sine-hyperbolic Arrhenius equation, and deformation activation energy (Q) was calculated to be 157.8 kJ/mol. The Q values of the extruded nanohybrid/AZ80 composite in this study and other similar studies on extruded AZ80 alloys were compared in order to analyze the effect of the addition of reinforcement, and the effects of deformation conditions on activation energy were analyzed. Finally, the compression microstructure in an unstable condition was carefully analyzed, and results indicated that the phenomenon of local instability was easy to occur at the compression specimen of the nanohybrid/AZ80 composite under deformation conditions of low temperature with high strain rate (300 °C, 0.1–0.01 s−1), and high temperature with low strain rate (450 °C, 0.0001 s−1).

Highlights

Compared with traditional iron and steel materials, magnesium alloys have the advantage of lower density, higher specific strength, and stronger damping capacity
Results can can still still be be explained explained by bythe thecompetition competitionbetween betweenwork-hardening work-hardening and anddynamic-softening dynamic-softening effects [16,17]
The deformation time of the composite was shortened, as was the effective time of dislocation slip and climb, and the softening effect of dynamic recrystallization was suppressed to a certain extent, thereby increasing peak stress and strain, which balanced dynamic recrystallization softening and work hardening

Summary

Introduction

Compared with traditional iron and steel materials, magnesium alloys have the advantage of lower density, higher specific strength, and stronger damping capacity. The AZ80 alloy has attractive combination properties among magnesium alloys, such as high strength, good plasticity, and excellent deformation ability, but their high temperature strength is relatively poor, which limits their development and application [3]. Various types of micro or nano reinforcement, such as SiC [4], CNT [5], and Al2 O3 [6], were introduced into the AZ80 magnesium alloy to combat this limitation. It is greatly important to study the relationship between deformation behavior and deformation conditions (temperature, strain rate, and deformation degree), which could optimize the hot workability and forming processes of composites [7]. The flow behaviors of materials during deformation processes are usually described by the constitution relationship. The deformation mechanism is generally analyzed by deformation activation energy (Q), which directly reflects workability to some extent [8]

Methods

Results

Conclusion