In this study,surface mechanical attrition treatment was employed to sucessfully produce a gradient nanostructured layer on WE43 magnesium alloy.X-ray diffraction,energy dispersive X-ray spectrometer,and high-resolution transmission electron microscope observations were mainly performed to uncover the microstructure evolution responsible for the refinement mechanisms.It reveals that the grain refine-ment process consists of three transition stages along the depth direction from the core matrix to the topmost surface layer,i.e.,dislocation cells and pile-ups,ultrafine subgrains,and randomly orientated nanograins with the grain size of～40 nm.Noticeably,the original Mg3RE second phase is also expe-rienced refinement and then re-dissolved into the α-Mg matrix phase,forming a supersaturated solid solution nanostructured α-Mg phase in the gradient refined layer.Due to the cooperative effects of grain refinement hardening,dislocation hardening,and supersaturated solid-solution hardening,the gradient nanostructured WE43 alloy contributes to the ultimate tensile strength of～435 MPa and ductility of～11.0％,showing an extraordinary strain hardening and mechanical properties among the reported se-vere plastic deformation-processed Mg alloys.This work provides a new strategy for the optimization of mechanical properties of Mg alloys via combining the gradient structure and supersaturated solid solu-tion.

Wanting Sun;Bo Wu;Hui Fu;Xu-Sheng Yang;Xiaoguang Qiao;Mingyi Zheng;Yang He;Jian Lu;San-Qiang Shi

State Key Laboratory of Ultra-precision Machining Technology,Department of Industrial and Systems Engineering,The Hong Kong Polytechnic University,Hung Hom,Hong Kong,China;Hong Kong Polytechnic University Shenzhen Research Institute,Shenzhen,China;School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China;Centre for Composite Materials and Structures,Harbin Institute of Technology,Harbin 150080,China;Department of Mechanical Engineering,City University of Hong Kong,Kowloon,Hong Kong,China;Department of Mechanical Engineering,The Hong Kong Polytechnic University,Hung Hom,Hong Kong,China

材料科学技术（英文版）

[1]Wanting Sun;Bo Wu;Hui Fu;Xu-Sheng Yang;Xiaoguang Qiao;Mingyi Zheng;Yang He;Jian Lu;San-Qiang Shi-.Combining gradient structure and supersaturated solid solution to achieve superior mechanical properties in WE43 magnesium alloy)[J].材料科学技术（英文版）,2022(04):223-238

sucessfully,subgrains,Mg3RE

Combining,gradient,supersaturated,solid,achieve,superior,mechanical,properties,WE43,magnesium,In,this,study,surface,attrition,treatment,was,employed,produce,nanostructured,layer,ray,diffraction,energy,dispersive,spectrometer,high,resolution,transmission,electron,microscope,observations,were,mainly,performed,uncover,microstructure,evolution,responsible,refinement,mechanisms,It,reveals,that,consists,three,transition,stages,along,depth,direction,from,core,matrix,topmost,dislocation,cells,pile,ups,ultrafine,randomly,orientated,nanograins,size,Noticeably,original,second,phase,also,expe,rienced,then,dissolved,into,forming,refined,Due,cooperative,effects,hardening,contributes,ultimate,tensile,strength,ductility,showing,extraordinary,strain,among,reported,vere,plastic,deformation,processed,alloys,This,work,provides,new,strategy,optimization,via,combining

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