期刊
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
卷 95, 期 -, 页码 40-56出版社
JOURNAL MATER SCI TECHNOL
DOI: 10.1016/j.jmst.2021.03.069
关键词
Additive manufacturing; Al-Mg-Sc-Zr alloys; Laser powder bed fusion; Heterogeneous microstructure; Deformation behavior
资金
- National Key Research and Development Program of China [2018YFB1106302, 2016YFB1100104]
- National Natural Science Foundation of China [52005411]
By using laser powder bed fusion to process Sc/Zr-modified Al-based alloys, the precipitation behavior of primary Al-3(Sc,Zr) was studied. It was found that the precipitation of primary Al-3(Sc,Zr) could be effectively suppressed in the inner region of the molten pool, inducing the formation of a heterogeneous alpha-Al matrix. Direct aging introduced heterogeneous secondary Al-3(Sc,Zr) precipitates within alpha-Al matrix, resulting in reduced mechanical heterogeneity and improved tensile ductility.
Laser powder bed fusion (L-PBF) of Sc/Zr-modified Al-based alloys has recently become a promising method for developing a new generation of high-performance Al alloys. To clarify the modification roles of Sc/Zr elements, an Al-4.66Mg-0.48Mn-0.72Sc-0.33Zr (wt.%) alloy was processed using L-PBF. The effect of the local solidification condition of the molten pool on the precipitation behavior of primary Al-3(Sc,Zr) was analyzed based on time-dependent nucleation theory. It was found that primary Al-3 (Sc,Zr) inevitably precipitated at the fusion boundary, while its precipitation could be effectively suppressed in the inner region of the molten pool. This subsequently induced the formation of a heterogeneous alpha-Al matrix. After direct aging, the heredity of solidification microstructure introduced heterogeneous secondary Al-3 (Sc,Zr) precipitates within alpha-Al matrix. Owing to the inverse relationship between grain boundary strengthening and precipitation strengthening, the direct-aged sample with dual heterogeneous structures exhibited reduced mechanical heterogeneity, resulting in lowered hetero-deformation-induced hardening. The low strain-hardening capability in the direct-aged sample promoted necking instability while inducing a large Luders elongation, which effectively improved the tensile ductility. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.
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