The construction and application of traditional high-strength 7075 aluminum alloy(A17075)through selective laser melting(SLM)are currently restricted by the serious hot cracking phenomenon.To address this critical issue,in this study,Si is employed to assist the SLM printing of high-strength A17075.The laser energy density during SLM is optimized,and the effects of Si element on solidification path,relative density,microstructure and mechanical properties of A17075 alloy are studied systematically.With the modified solidification path,laser energy density,and the dense microstructure with refined grain size and semi-continuous precipitates network at grain boundaries,which consists of fine Si,β-Mg2Si,Q-phase andθ-A12Cu,the hot cracking phenomenon and mechanical properties are effectively improved.As a result,the tensile strength of the SLM-processed Si-modified A17075 can reach 486±3 MPa,with a high relative density of～99.4％,a yield strength of 291±8 MPa,fracture elongation of(6.4±0.4)％and hardness of 162±2(HV0.2)at the laser energy density of 112.5 J/mm3.The main strengthening mechanism with Si modification is demonstrated to be the synergetic enhancement of grain refinement,solution strengthening,load transfer,and dislocation strengthening.This work will inspire more new design of high-strength alloys through SLM.

Junwei Sha;Meixian Li;Lizhuang Yang;Xudong Rong;Bowen Pu;Dongdong Zhao;Simi Sui;Xiang Zhang;Chunnian He;Jianglin Lan;Naiqin Zhao

School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials,Tianjin University,Tianjin 300350,China;Collaborative Innovation Center of Chemical Science and Engineering,Tianjin 300350,China;Key Laboratory of Advanced Ceramics and Machining Technology,Ministry of Education,Tianjin 300350,China;Central Iron and Steel Research Institute(CISRI),Beijing 100081,China

金属学报（英文版）

[1]Junwei Sha;Meixian Li;Lizhuang Yang;Xudong Rong;Bowen Pu;Dongdong Zhao;Simi Sui;Xiang Zhang;Chunnian He;Jianglin Lan;Naiqin Zhao-.Si-Assisted Solidification Path and Microstructure Control of 7075 Aluminum Alloy with Improved Mechanical Properties by Selective Laser Melting)[J].金属学报（英文版）,2022(09):1424-1438

A17075,A12Cu

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