Suzuki Asuka, Sasa Yusuke, Kobashi Makoto, Kato Masaki, Segawa Masahito, Shimono Yusuke, Nomoto Sukeharu
Department of Materials Process Engineering, Graduate School of Engineering, Nagoya University, 1, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Aichi Center for Industry and Science Technology, 1267-1 Akiai, Yakusa-cho, Toyota 470-0356, Japan.
Materials (Basel). 2023 Nov 18;16(22):7228. doi: 10.3390/ma16227228.
The laser powder bed fusion (L-PBF) process provides the cellular microstructure (primary α phase surrounded by a eutectic Si network) inside hypo-eutectic Al-Si alloys. The microstructure changes to the particle-dispersed microstructure with heat treatments at around 500 °C. The microstructural change leads to a significant reduction in the tensile strength. However, the microstructural descriptors representing the cellular and particle-dispersed microstructures have not been established, resulting in difficulty in terms of discussion regarding the structure-property relationship. In this study, an attempt was made to analyze the microstructure in L-PBF-built and subsequently heat-treated Al-12Si (mass%) alloys using the persistent homology, which can analyze the spatial distributions and connections of secondary phases. The zero-dimensional persistent homology revealed that the spacing between adjacent Si particles was independent of Si particle size in the as-built alloy, whereas fewer Si particles existed near large Si particles in the heat-treated alloy. Furthermore, the first principal component of a one-dimensional persistent homology diagram would represent the microstructural characteristics from cellular to particle-dispersed morphology. These microstructural descriptors were strongly correlated with the tensile and yield strengths. This study provides a new insight into the microstructural indices describing unique microstructures in L-PBF-built alloys.
激光粉末床熔融（L-PBF）工艺在亚共晶Al-Si合金内部形成了胞状微观结构（初生α相被共晶硅网络包围）。在约500℃进行热处理时，微观结构转变为颗粒弥散型微观结构。这种微观结构的变化导致抗拉强度显著降低。然而，表征胞状和颗粒弥散型微观结构的微观结构描述符尚未建立，这使得在讨论结构-性能关系时存在困难。在本研究中，尝试使用持久同调分析L-PBF制备并随后进行热处理的Al-12Si（质量%）合金的微观结构，持久同调可以分析第二相的空间分布和连接情况。零维持久同调表明，在铸态合金中相邻硅颗粒之间的间距与硅颗粒尺寸无关，而在热处理合金中，大尺寸硅颗粒附近存在的硅颗粒较少。此外，一维持久同调图中的第一主成分将代表从胞状到颗粒弥散型形态的微观结构特征。这些微观结构描述符与抗拉强度和屈服强度密切相关。本研究为描述L-PBF制备合金中独特微观结构的微观结构指标提供了新的见解。
