Damage mechanisms in selective laser melted AlSi10Mg under as built and different post-treatment conditions
Damage mechanisms in selective laser melted AlSi10Mg under as built and different post-treatment conditions
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DOI：
10.1016/j.msea.2019.138210
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发表时间：
2019-09-09
期刊：
影响因子：
6.4
通讯作者：
Simar, Aude
中科院分区：
文献类型：
--
作者：
Zhao, Lv;Macias, Juan Guillermo Santos;Simar, Aude
选择性激光熔化（SLM）制造的AlSi10Mg合金呈现出精细的富硅网络和析出物，其赋予高机械强度但低延展性。后处理旨在消除与SLM相关的固有缺陷，如残余应力、孔隙度或不均匀性，导致微观结构发生显著变化，并影响后处理材料的硬化和损伤机制。本工作致力于研究SLM AlSi 10 Mg的断裂下建成和三个后处理条件下，即两个应力消除热处理和搅拌摩擦加工（FSP）。结果发现，互连的Si网络在低应变下由于Si相的脆性而促进损伤。损伤的开始将载荷转移到封闭的Al相，然后在高应力下快速断裂，从而导致低的材料延展性。相反，当Si网络球化成Si颗粒时，即使在后处理后仍保持显微组织的孔隙率和不均匀性的情况下，延展性也高度增加。塑性增强的结果从延迟在Si颗粒上的空洞形核，以及从在Al基体中的空洞生长的宽容。
Selective laser melting (SLM) manufactured AlSi10Mg alloys present a fine silicon-rich network and precipitates which grant high mechanical strength but low ductility. Post-treatments, aiming at eliminating inherent defects related to SLM such as residual stresses, porosity or inhomogeneity, result in significant changes in the microstructure and impact both the hardening and the damage mechanisms of the post-treated material. The present work is dedicated to the investigation of the fracture of SLM AlSi10Mg under as built and three post-treatment conditions, namely two stress relieve heat treatments and friction stir processing (FSP). It is found that the interconnected Si network fosters damage at low strain due to the brittleness of the Si phase. The onset of damage transfers load to the enclosed Al phase which then fractures quickly under high stress, thus leading to low material ductility. In contrast, when the Si network is globularized into Si particles, the ductility is highly increased even in the case where the porosity and inhomogeneity of the microstructure remain after the post-treatment. The ductility enhancement results from the delay in void nucleation on the Si particles as well as from the tolerance for void growth in the Al matrix.