|About this Abstract
||7th World Congress on Integrated Computational Materials Engineering (ICME 2023)
||Composition-microstructure Control of in-situ Alloying Using Laser Powder-bed Fusion Additive Manufacturing: High-fidelity Thermal-chemical-fluid-microstructure Modelling
||Junji Shinjo, Chinnapat Panwisawas
|On-Site Speaker (Planned)
Nucleation and grain growth during metal additive manufacturing (AM) remain debatable since the nature of rapid melting and solidification induced by laser-powder interaction during AM may cause heterogeneous mixing liquid metal behaviour especially when in-situ alloying is used. Coupled thermal-chemical-fluid-microstructure modelling is developed for simulating in-situ AM to understand the chemistry-induced solidification, re-melting and microstructure development. The results indicate that thermal fluid flow and chemical mixing play an important role in rapidly solidified microstructure. The heterogeneous nucleation resulting from undercooling due to large thermal gradient and large cooling rate initiates grain nuclei forming equiaxed grains, and with the extent of thermal gradient, more anisotropic columnar grain growth occurs in AM. The keyhole serves as a strong stirrer to enhance chemical species mixing by inducing convective flow motion, which determines the local chemical composition and microstructure in in-situ alloying while melting newly fed powders and re-melting part of the previous layer.