Additive manufacturing exhibits great potentials for the fabrication of novel materials due to its unique non-equilibrium solidification and heating process.In this work,a novel nano-oxides dispersion strength-ened Co28Cr9W1.5Si(wt.％)alloy,fabricated by laser powder bed fusion(LPBF),was comprehensively in-vestigated.During the layer-by-layer featured process,in-situ formation of Si rich,amorphous,nano-oxide inclusions was observed,whose formation is ascribed to the high affinity of Si to oxygen.Meanwhile,distinctive body-centered cubic(BCC)Co5Cr3Si2 nano-precipitates with an 8-fold symmetry were also confirmed to appear.The precipitates,rarely reported in previous studied Co-Cr alloys,were found to tightly bond with the in-situ oxidization.Furthermore,the morphologies,the size distributions as well as the microstructure of the interface between the matrix and the inclusions were investigated in detail and their influence on the tensile deformation was also clarified.The existence of transition boundaries be-tween these inclusions and the matrix strongly blocked the movement of dislocations,thereby increasing the strength of the alloy.It was understood that when the plastic deformation proceeds,the fracture oc-curs in the vicinity of the oxide inclusions where dislocations accumulate.A quantitative analysis of the strengthening mechanism was also established,in which an additional important contribution to strength(～169 MPa)caused by the effects of in-situ formed oxide inclusions was calculated.

Kefeng Li;Zhi Wang;Kaikai Song;Khashayar Khanlari;Xu-Sheng Yang;Qi Shi;Xin Liu;Xinhua Mao

Institute of New Materials,Guangdong Academy of Sciences,Guangzhou 510650,China;National Engineering Research Center of Powder Metallurgy of Titanium and Rare Metals,Guangzhou 510650,China;Guangdong Key Laboratory for Advanced Metallic Materials Processing,South China University of Technology,Guangzhou 510641,China;School of Mechanical,Electrical and Information Engineering,Shandong University,Weihai 264209,China;Advanced Manufacturing Technology Research Center,Department of Industrial and Systems Engineering,The Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong,China;Hong Kong Polytechnic University Shenzhen Research Institute,Shenzhen 518000,China

材料科学技术（英文版）

[1]Kefeng Li;Zhi Wang;Kaikai Song;Khashayar Khanlari;Xu-Sheng Yang;Qi Shi;Xin Liu;Xinhua Mao-.Additive manufacturing of a Co-Cr-W alloy by selective laser melting:In-situ oxidation,precipitation and the corresponding strengthening effects)[J].材料科学技术（英文版）,2022(30):171-181

Co28Cr9W1,Co5Cr3Si2

Additive,manufacturing,selective,laser,melting,In,situ,oxidation,precipitation,corresponding,strengthening,effects,exhibits,great,potentials,fabrication,novel,materials,due,unique,equilibrium,solidification,heating,process,this,work,nano,oxides,dispersion,ened,5Si,wt,fabricated,powder,fusion,LPBF,was,comprehensively,During,layer,featured,rich,amorphous,inclusions,observed,whose,ascribed,high,affinity,oxygen,Meanwhile,distinctive,body,centered,cubic,BCC,precipitates,fold,symmetry,were,also,confirmed,appear,rarely,reported,previous,studied,alloys,found,tightly,bond,oxidization,Furthermore,morphologies,size,distributions,well,microstructure,interface,between,matrix,investigated,detail,their,influence,tensile,deformation,clarified,existence,transition,boundaries,these,strongly,blocked,movement,dislocations,thereby,increasing,It,understood,that,when,plastic,proceeds,fracture,curs,vicinity,where,accumulate,quantitative,analysis,mechanism,established,which,additional,important,contribution,caused,formed,calculated

0.577561