期刊
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
卷 52, 期 1, 页码 194-210出版社
SPRINGER
DOI: 10.1007/s11661-020-06073-9
关键词
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资金
- European Union's Horizon 2020 Clean Sky 2 research and innovation program [755610]
- KU Leuven [GOA/15/012]
- China Scholarship Council [201706220083]
- H2020 Societal Challenges Programme [755610] Funding Source: H2020 Societal Challenges Programme
The study developed a Si-modified Al7075 alloy to reduce solidification cracking during L-PBF, resulting in crack-free samples with improved microstructure and grain size. The addition of Si, Mg2Si, and Al2Cu phases in the modified alloy contributed to the enhanced mechanical properties and age hardening resistance.
Fabrication of high strength aluminum alloys using laser-based powder bed fusion (L-PBF) encounters challenges, including the occurrence of solidification cracks and the loss of volatile elements, such as Zn and Mg. The current work developed a Si-modified Al7075 alloy aiming at introducing eutectic phases to mitigate the solidification cracking during L-PBF. Based on Kou's model, the addition of Zn and Mg decreased the crack susceptibility from 6504 degrees C to 5966 degrees C, and the addition of 3.74 wt pct of Si further decreased the crack susceptibility to 3960 degrees C. The Al7075 alloy fabricated by L-PBF exhibited a large amount of solidification cracks extending throughout the sample. Crack-free samples with a relative density of 99.94 pct, as inspected by X-ray microcomputed tomography, were achieved for the developed Si-modified Al7075 alloy. The microstructure showed a transition from a coarse columnar microstructure to a refined mixed columnar + equiaxed microstructure after alloy modification, with a concomitant grain size reduction from 59.0 +/- 42.2 to 15.0 +/- 9.4 mu m. Moreover, Si, Mg2Si, and Al2Cu phases were detected in the Si-modified Al7075 alloy. After a direct ageing heat treatment, the Si-modified Al7075 alloy showed minimal age hardening effect with a peak hardness of (146 +/- 3 Hv).
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