Simultaneously Enhanced Strength and Ductility of Al⁻Mg⁻Si Alloys during Aging Process Induced by Electro-Pulsing Treatment.

Yitong Wang,Wenqiang Jiang,Xiaofeng Xu,Dong Pan,Yuguang Zhao,Xueying Chong

doi:10.3390/ma12091383

Abstract

Most methods used for strengthening metallic materials, such as thermal-mechanical treatment, will sacrifice the ductility. A novel technology, electric pulsing treatment (EPT), is applied to break this trade-off, which produces an Al–Mg–Si alloy with superior ductility and higher strength within only 560 ms. Systematic electron microscopy characterization and finite element simulation reveal that EPT promotes the formation of clusters Mg2(Si,Cu)3 and sub-grain boundaries. The results of quantitative calculation indicate that the dislocation entanglement is delayed due to the existence of clusters and longer dislocation glide distance, so that ultimate strength is fully improved. Moreover, the superior ductility is mainly governed by sub-grains which lead to higher mobile dislocation density, appearance of new crystal orientations, and prevention of crack propagation. Thereupon, this interesting finding paves the way in developing the Al–Mg–Si alloy with higher mechanical properties efficiently.

Highlights

Al–Mg–Si alloys are promising structural materials to develop automobile manufacturing and railway components because of the combination of lightweight and advanced anti-corrosion [1].The major strengthening approach for this alloy is the Orowan mechanism, namely the strength increment is caused by interactions between dislocations and acicular monoclinic Mg2 Si phase [2].Generally, the strength and ductility of these alloys are mutually exclusive during the aging process i.e., increment of strength usually accompany with decrease in ductility.the comprehensive mechanical properties cannot be simultaneously improved to satisfy the requirements to further develop the technology of transportation industry.The grain refinement strengthening was deemed to be a method which can break the trade-off relationship
The trade-off relationship between strength and ductility of 6061 alloy during aging process was broken by electro-pulsing treatment
Plenty of Mg2 (Si,Cu)3 co-clusters appeared after electro-pulsing treatment

Summary

Introduction

Al–Mg–Si alloys are promising structural materials to develop automobile manufacturing and railway components because of the combination of lightweight and advanced anti-corrosion [1].The major strengthening approach for this alloy is the Orowan mechanism, namely the strength increment is caused by interactions between dislocations and acicular monoclinic Mg2 Si phase [2].Generally, the strength and ductility of these alloys are mutually exclusive (trade-off relationship) during the aging process i.e., increment of strength usually accompany with decrease in ductility.the comprehensive mechanical properties cannot be simultaneously improved to satisfy the requirements to further develop the technology of transportation industry.The grain refinement strengthening was deemed to be a method which can break the trade-off relationship. Al–Mg–Si alloys are promising structural materials to develop automobile manufacturing and railway components because of the combination of lightweight and advanced anti-corrosion [1]. The major strengthening approach for this alloy is the Orowan mechanism, namely the strength increment is caused by interactions between dislocations and acicular monoclinic Mg2 Si phase [2]. The strength and ductility of these alloys are mutually exclusive (trade-off relationship) during the aging process i.e., increment of strength usually accompany with decrease in ductility. The comprehensive mechanical properties cannot be simultaneously improved to satisfy the requirements to further develop the technology of transportation industry. The grain refinement strengthening was deemed to be a method which can break the trade-off relationship. Deformation combined with thermal treatment, as a widely adopted grain refinement approach through dynamic recrystallization, can enhance the mechanical properties effectively

Methods

Results

Conclusion