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| Microstructure and mechanical properties of high strength Al-Mg-Sc-Er-Zr alloy fabricated by laser powder bed fusion |
| WANG Yangbo1, LI Ruidi1, ZHI Shengxing1, YUAN Tiechui1, KE Linda2, HOU Yaping3 |
1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Shanghai Aerospace Precision Machinery Institute, Shanghai 201600, China;
3. Hunan institute of metrology and test, Changsha 410000, China |
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Abstract Al-Mg-Sc-Zr alloy fabricated by laser powder bed fusion (LPBF) technology is not easy to crack and has good mechanical properties. However, Sc is expensive, it is necessary to find some elements that can replace Sc. This article used gas atomized powder as raw material and prepared Al-Mg-Sc-Er-Zr alloy by LPBF technology. Density was measured using hydrostatic balance and defects were observed using a metallographic microscope to optimize laser process parameters; the hardness was measured using a Vickers hardness tester and tensile tests were conducted using a universal mechanical testing machine to optimize the aging process parameters; scanning electron microscope and transmission electron microscope were used to characterize the alloy structure and study its strengthening mechanism. The results indicate that the optimized LPBF process parameters are: laser power of 300 W, scanning speed of 900 mm/s; the optimized aging process parameters are: aging temperature of 325 ℃ and aging time of 4 h. Al-Mg-Sc-Er-Zr alloy prepared by LPBF exhibits a typical bimodal grain structure, with fine equiaxed grains at the boundary of the melt pool and coarse columnar grains inside the melt pool. After aging treatment at 325 ℃/4 h, the tensile strength of the alloy reaches 565 MPa, the yield strength reaches 520 MPa, the elongation rate is 14.5%, and the hardness (HV) increase from 118 before aging to 163. Mg2Si particles and nano Al3(Sc,Zr) particles formed after aging treatment can synergistically nail grain boundaries and improve alloy strength.
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Received: 22 August 2024
Published: 05 February 2025
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2024, Vol. 29 
