Microstructure evolution and mechanical properties of high-performance Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion
(1. National Engineering Research Center of Near-net Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China;
2. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
3. Institute of Advanced Additive Manufacturing, Ji Hua Laboratory, Foshan 528200, China)
2. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
3. Institute of Advanced Additive Manufacturing, Ji Hua Laboratory, Foshan 528200, China)
Abstract: The influence of aging temperatures on the microstructure and mechanical properties of an Al-Mn-Mg- Sc-Zr alloy prepared by laser powder bed fusion (L-PBF) was systematically studied. The results show that the fabricated alloy was a dense and crack-free piece with a fine grain size of 3.51 μm and a yield strength of (547±3) MPa. When the alloy was subjected to aging at 300 °C, a large amount of highly coherent Al3Sc nanoparticles (2-3 nm) precipitated from the Al matrix. The aged sample exhibited a high yield strength of (616±4) MPa, which can be attributed to precipitation strengthening, solid solution strengthening, and grain boundary strengthening. When the alloy was aged at a temperature higher than 300 °C, part of the dissolved Mn and Zr precipitated in the form of Al6Mn and Al3(Sc,Zr). When the alloy was aged at 500 °C, the Al6Mn and Al3(Sc,Zr) precipitates grew to approximately 600 and 30 nm, respectively, in size. Consequently, the yield strength of the alloy decreased to (372±3) MPa.
Key words: laser powder bed fusion; Al-Mn-Mg-Sc-Zr alloy; microstructure evolution; mechanical properties; Al3Sc nanoparticle