Microstructure and Mechanical Properties of Al-Si-Mg-Zr Alloy Fabricated by Selective Laser Melting

Author of the article:ZAI Chunfeng1 , GENG Yaoxiang1 , LUO Jinjie1,2, YU Jiang1 , ZHANG Zhijie1 , JU Hongbo1 , XU Junhua1

Author's Workplace：1. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China; 2. Kunshan Guoli Electronic Technology Co., Ltd., Kunshan 215333, China

Key Words：selective laser melting; Al-Si-Mg-Zr alloy; heat treatment; microstructure; mechanical property

Abstract：Based on a high Mg-content Al-Si-Mg alloy, a Zr-modified Al-8.0Si-2.56Mg-0.41Zr alloy was designed and prepared by selective laser melting (SLM) in this paper. The effects of different laser scanning speeds on the formability of alloy powder and different aging treatment conditions on the microstructure and mechanical properties of SLM-formed samples were systematically studied. The results show that the alloy exhibits good SLM formability with a maximum relative density of approximately 99.5%. The sample is composed of fine equiaxed crystals distributed at the boundary of the molten pool and columnar crystals inside the molten pool. The grain size of the sample is significantly smaller than that of the selective laser melted Al-Si-Mg alloy. The maximum hardness of the SLM-formed samples is (173±2) HV. When the aging temperature is less than or equal to 200 ℃, the Vickers hardness of the sample increases with increasing aging temperature; when the aging temperature is over or equal to 250 ℃, the hardness of the sample decreases rapidly. The hardness and compressive yield strength of the sample gradually increase with prolonged aging time at 150 ℃. The sample after aging treatment at 150 ℃ for 12 h shows the maximum hardness and compressive yield strength, which are (194±2) HV and (512±4) MPa, respectively.