Microstructure and mechanical properties of Al-Mg-Sc-Zr alloy prepared by selective laser melting
ZHU Xi1, YUNA Tiechui1,2, WANG Minbu1,2, HUANG Lan1, LI Ruidi1,2, LÜ liang3, YI Chushan3, LUO Qiang3
1. State key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. Shenzhen Research Institute, Central South University, Shenzhen 518057, China; 3. AECC South Industry Company Limited, Zhuzhou 410000, China
Abstract：Al-Mg-Sc-Zr alloy were prepared by selective laser melting (SLM) technology with gas atomization powders as raw materials. The effects of processing parameters on metallurgical defects, microstructure, and tensile properties of SLM-fabricated samples were investigated through optical microscope analysis, scanning electron microscopy analysis, and unidirectional tensile test at room temperature, etc. The results show that SLM-fabricated Al-Mg-Sc-Zr alloy is characterized with mixed grains structure in which fine equiaxed grains and coarse columnar grains alternate. It can be obviously found that element segregation in fine equiaxed grain region and precipitated Al3(Sc,Zr) particles pin at the grain boundary. When the laser power increases from 260 W to 380 W, the porosity of the sample decreases first and then increases, while the changing trend of mechanical property is opposite. When the laser power is 300 W, the optimum parameter is obtained with the relative density reaching 99.4%. There are only a few small shrinkage pores in the sample due to the insufficient supply of liquid metal. The ultimate tensile strength, yield strength, and fracture elongation are 429.7 MPa, 363.5 MPa and 17.7%, respectively. After aging treatment at 325 ℃ for 10 h, the ultimate tensile strength, yield strength, and fracture elongation are 530.1 MPa, 506.4 MPa and 9.0%, respectively.
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2022, Vol. 27 
