Microstructure and High Temperature Tensile Properties of Mg–10Gd–5Y–0.5Zr Alloy after Thermo-Mechanical Processing

Guohua Wu,Xiaoqin Zeng,Dejiang Li,Wencai Liu,Wenjiang Ding,H Jafari Nodooshan

doi:10.3390/met8120980

Abstract

The microstructure, high-temperature tensile properties and fracture behavior of the Mg-10Gd-5Y-0.5Zr alloy after thermo-mechanical processing (pre-tension between solution and aging treatment) were investigated. The pre-deformed alloy shows the accelerated aging kinetics compared to the un-deformed alloy. Microstructure of pre-deformed samples showed not only the homogeneous nucleation of the precipitate but also heterogeneous nucleation of precipitates on the dislocation and twin boundaries. Tensile results show that the pre-deformation enhanced the strength of the alloy, while it deteriorates the ductility of the alloy. The ultimate tensile strength (UTS) of the T6 treated un-deformed and pre-deformed alloy at room temperature are 331 MPa and 366 MPa, respectively. Tensile strength of the T6 treated alloy in both un-deformed and deformed conditions was enhanced by raising the test temperature and then reduced by further raising the test temperature. The higher strength of the pre-deformed alloy could be related to the higher density of the precipitates, which grow on the twin boundaries and can hinder the dislocation movement and strengthen the alloy. The results shows that thermo-mechanical processing can significantly improve the room- and high-temperature mechanical properties and enhance the formation of precipitates in Mg-10Gd-5Y-0.5Zr alloy, which can lead to wider application of the alloy in industries such as aerospace or powertrains that need better room- and high-temperature mechanical properties.

Highlights

IntroductionAddition of rare earth elements is one of the promising ways to enhance the room- and high-temperature mechanical properties and creep resistance of magnesium alloys [2,3,4,5,6,7,8,9]
Magnesium alloys have attracted great interest for applications in the automotive and aerospace industries owing to their strong need for lighter vehicles to reduce fuel consumption [1].Addition of rare earth elements is one of the promising ways to enhance the room- and high-temperature mechanical properties and creep resistance of magnesium alloys [2,3,4,5,6,7,8,9]
Since the solubility of the rear earth elements declines with reducing temperature, the strength of these alloys is essentially enhanced by precipitation strengthening [1,10]

Summary

Introduction

Addition of rare earth elements is one of the promising ways to enhance the room- and high-temperature mechanical properties and creep resistance of magnesium alloys [2,3,4,5,6,7,8,9]. Since the solubility of the rear earth elements declines with reducing temperature, the strength of these alloys is essentially enhanced by precipitation strengthening [1,10]. With the purpose of enhancing the mechanical properties of these alloys, many efforts have been made to optimize the precipitation and microstructure by alloying, by rare earth (RE) elements such as gadolinium (Gd), yttrium (Y), samarium (Sm), erbium (Er), and neodymium (Nd) [2,3,4,8,11]. Addition of rare earth elements to magnesium alloys can improve the strength of the alloy but is costly.

Results

Discussion

Conclusion