期刊
MATERIALS & DESIGN
卷 198, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.matdes.2020.109339
关键词
Aluminum alloy; Additive manufacturing; Laser powder bed fusion (LPBF); Neutron diffraction; Residual stress; Dislocation density
资金
- project CustoMat_3D - German Federal Ministry of Education and Research (BMBF) [03XP0101I]
- Fraunhofer Cluster of Excellence Programmable Materials
In-situ neutron diffraction was used to investigate the residual strains, stresses, and dislocation density in LPBF AlSi10Mg during loading-unloading-reloading deformation. The study revealed that the AlSi10Mg alloy exhibits notable dislocation annihilation phenomenon in the Al matrix during unloading stages, driven by compressive residual stresses.
The plastic deformation of the AlSi10Mg alloy manufactured via laser powder bed fusion (LPBF) is incompatible at the microscale, which causes residual strains/stresses and dislocation pile-ups at the Al/Si interfaces and grain boundaries. Hence, it is of fundamental significance to clarify these microscopic properties during plastic deformation. Here, in-situ neutron diffraction is employed to explore the residual strains, stresses, and dislocation density in the LPBF AlSi10Mg during loading-unloading-reloading deformation. It is found that the maximum residual stresses of the Al and Si phases in the loading direction reach up to about -115 (compressive) and 832 (tensile) MPa, respectively. A notable dislocation annihilation phenomenon is observed in the Al matrix: the dislocation density decreases significantly during unloading stages, and the amplitude of this reduction increases after experiencing a larger plastic deformation. At the macroscale, this dislocation annihilation phenomenon is associated with the reverse strain after unloading. At the microscale, the annihilation phenomenon is driven by the compressive residual stress in the Al matrix. Meanwhile, the annihilation of screw dislocations during unloading stages contributes to the reduction in total dislocation density. (C) 2020 The Author(s). Published by Elsevier Ltd.
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