The Al-Mn-Sc-based alloys specific for additive manufacturing(AM)have been recently developed and can reach ultrahigh strength and adequate elongation.However,these alloys commonly exhibit non-uniform plasticity during tensile deformation,which is a critical issue hindering their wider application.In this work,the origin of this non-uniform plasticity of the alloys produced by laser powder bed fusion(LPBF)has been systematically investigated for the first time.The results show that the loss of uniform plasticity in the alloy originates from microstructural regions containing equiaxed fine-grains(FGs)(～650 nm in size)at the bottom of the melt pools.In micro-tensile tests,the strength of these FG regions can reach a peak of～630 MPa.After this,an apparent yield drop occurs,followed by rapid strain softening.This FG behavior is associated with intermetallic particles along grain boundaries and a lack of uniform mobile dislocations during deformation.The columnar coarse-grain(CG)regions in the remaining melt pools show uniform plasticity and moderate work hardening.Furthermore,the quantitative calculations indicate that the solid solution strengthening in these two regions is similar.Nevertheless,secondary Al3Sc precipitates contribute to～260 MPa strength in the FG,compared to 310 MPa in the CG due to their different number density.In addition,grain boundary strengthening can reach 230 MPa in the FG region;nearly double the CG region value.

Dina Bayoumy;Kwangsik Kwak;Torben Boll;Stefan Dietrich;Daniel Schliephake;Jie Huang;Junlan Yi;Kazuki Takashima;Xinhua Wu;Yuman Zhu;Aijun Huang

Monash Centre for Additive Manufacturing,15-17 Normanby Rd,Notting Hill,VIC 3168,Australia;Department of Materials Science and Engineering,Monash University,Clayton,VIC 3800,Australia;Department of Materials Science and Engineering,Kumamoto University,2-39-1 Kurokami,Chuo-ku,Kumamoto 860-8555,Japan;Karlsruhe Nano Micro Facility(KNMF),Karlsruhe Institute of Technology(KIT),Hermann-von-Helmholtz-Platz 1,76344,Eggenstein-Leopoldshafen,Germany;Institute for Applied Materials(IAM-WK),Karlsruhe Institute of Technology(KIT),Engelbert-Arnold-Stra?e 4,76131 Karlsruhe,Germany;Aeronautical Manufacturing Technology Institute,Shanghai Aircraft Manufacturing Co.,Ltd.,Shanghai 201324,China

材料科学技术（英文版）

[1]Dina Bayoumy;Kwangsik Kwak;Torben Boll;Stefan Dietrich;Daniel Schliephake;Jie Huang;Junlan Yi;Kazuki Takashima;Xinhua Wu;Yuman Zhu;Aijun Huang-.Origin of non-uniform plasticity in a high-strength Al-Mn-Sc based alloy produced by laser powder bed fusion)[J].材料科学技术（英文版）,2022(08):121-133

Origin,uniform,plasticity,Mn,produced,by,laser,powder,bed,fusion,alloys,specific,additive,manufacturing,AM,have,been,recently,developed,can,reach,ultrahigh,adequate,elongation,However,these,commonly,exhibit,during,tensile,deformation,which,critical,issue,hindering,their,wider,application,In,this,work,LPBF,has,systematically,investigated,first,results,show,that,loss,originates,from,microstructural,regions,containing,equiaxed,fine,grains,FGs,size,bottom,melt,pools,tests,peak,After,apparent,yield,drop,occurs,followed,rapid,strain,softening,This,behavior,associated,intermetallic,particles,along,boundaries,lack,mobile,dislocations,columnar,coarse,CG,remaining,moderate,hardening,Furthermore,quantitative,calculations,indicate,solid,solution,strengthening,two,similar,Nevertheless,secondary,Al3Sc,precipitates,contribute,compared,due,different,number,density,addition,boundary,nearly,double,value

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