The properties of modified conventional wrought aluminum alloys cannot be significantly enhanced by normal post-heat treatment in that the fine-grained strengthening,arising from high cooling rate in SLM,is underutilized.In this work,compared with the normal T6 heat treatment,a novel simple direct ag-ing regime was proposed to maintain the grain-boundary strengthening and to utilize the precipitation strengthening of secondary Al3Zr.It was found that a heterogeneous grain structure,which consisted of ultrafine equiaxed(～0.82 μm)and columnar(～1.80 μm)grains at the bottom and top of molten pool,respectively,was formed in the SLM processed sample.After direct aging(DA),the ultrafine grains were maintained and a mass of spherical coherent L12-Al3Zr particles with a mean radius of approximately 1.15 nm was precipitated.In contrast,after solution treatment and aging(STA),a significant grain coars-ening occurred in the equiaxed grain region.Meanwhile,the coarsening L12-Al3Zr particles,nano-sized S'phases and GPB zones were detected in the STA sample.This subsequently induced that the yield strength of the DA sample(～435 MPa)was higher than that of the STA sample(～402 MPa)owing to the grain boundary strengthening and precipitation strengthening.Both the STA and DA samples exhibited a higher strength than that of the other SLMed Al-Cu-Mg series alloys;this was comparable to that of the wrought AA2024-T6 alloy(～393 MPa).Both the STA and DA samples exhibited a higher strength than that of the other SLMed Al-Cu-Mg series alloys;this was comparable to that of the wrought AA2024-T6 alloy(～393 MPa).

State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China;Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design,MIIT China,Northwestern Polytechnical University,Xi'an 710072,China

[1]Yanfang Wang;Xin Lin;Nan Kang;Zihong Wang;Yuxi Liu;Weidong Huang-.Influence of post-heat treatment on the microstructure and mechanical properties of Al-Cu-Mg-Zr alloy manufactured by selective laser melting)[J].材料科学技术（英文版）,2022(16):35-48

coars,SLMed

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