Superplastic Deformation Behavior of Rolled Mg-8Al-2Sn and Mg-8Al-1Sn-1Zn Alloys at High Temperatures.

Shao-You Zhang,Hui-Yuan Wang,Long-Qing Zhao,Cheng Wang,Jin Xu,Jia-Wang Song,Xiu-Ming Cheng,Pin-Kui Ma

doi:10.3390/ma13051074

Shao-You Zhang, Hui-Yuan Wang + Show 6 more

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https://doi.org/10.3390/ma13051074

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Abstract

The high-temperature superplastic deformation behavior of rolled Mg-8Al-2Sn (AT82) and Mg-8Al-1Sn-1Zn (ATZ811) alloys were investigated in this study. During tensile deformation at 573 K, no obvious grain growth occurred in both alloys, because of the high-volume fraction of second phases located at grain boundaries. Meanwhile, texture weakening was observed, suggesting that grain boundary sliding (GBS) is the dominant superplastic deformation mechanism, which agreed well with the strain rate sensitivity (m) and the activation energy (Q) calculations. The microstructural evolution during tensile deformation manifested that there were more and larger cavities in AT82 than ATZ811 during high-temperature tensile deformation. Therefore, superior superplasticity was found in the ATZ811 alloy that presented a tensile elongation of ~510% under a strain rate of 10−3 s−1 at 573 K, in contrast to the relatively inferior elongation of ~380% for the AT82 alloy. Meanwhile, good tensile properties at ambient temperature were also obtained in ATZ811 alloy, showing the ultimate tensile strength (UTS) of ~355 MPa, yield strength (YS) of ~250 MPa and elongation of ~18%. Excellent mechanical performance at both ambient and elevated temperatures can be realized by using economical elements and conventional rolling process, which is desirable for the industrial application of Mg alloy sheets.

Highlights

As the lightest metallic structural materials among those developed far, magnesium (Mg) and its alloys have been developing as one of the promising materials in the aerospace and automotive industries [1,2,3]
The results show that there are no disparities in SRC curves between the two alloys, and the average values of the strain rate sensitivity (m) measured from the SRC tests are quite close, valuing ~0.52 and ~0.50 for AT82 and ATZ811, respectively
Room-temperature tensile properties and high-temperature superplasticity were investigated on the two alloys

Summary

Introduction

As the lightest metallic structural materials among those developed far, magnesium (Mg) and its alloys have been developing as one of the promising materials in the aerospace and automotive industries [1,2,3]. It is of great importance to attain novel Mg alloys with high superplasticity, and study their deformation behaviors at elevated temperatures. The Mg-Al based alloys are currently the most widely used Mg alloys because of their low cost and relevantly good properties [6], in particular for the Mg-Al-Zn alloys consisting of α-Mg matrix and β-Mg17 Al12 strengthening phases [7]. The softening of low melting-point Mg17 Al12 phase at elevated temperatures facilitates the interphase boundary sliding, and assists in developing their superplasticity [8]. Several reported studies have achieved the high-temperature superplasticity in

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Conclusion