Early Career Researcher: Student (poster and 2-minute poster pitch) at Digital Twin Symposium 2019, presented by Hongmei Zhang
Laser additive manufacturing has demonstrated a promising capability in the simultaneous formation of high-performance nanocomposites with unique microstructures. The present work studied the influence of scan speed (v) on microstructure growth, evolution mechanism and mechanical properties of TiC/Inconel 718 nanocomposites by selective laser melting (SLM) with experiments and mesoscopic simulations. The results showed that the low temperature gradient, high cooling rate, short lifespan and small velocity of molten liquid flow were obtained under a high scan speed. Accordingly, the surface morphology transformed from relatively smooth to hierarchical rough structures, and the nano-TiC experienced severe agglomeration to uniform distribution with the increase of v. Besides, the columnar dendrites spacing of γ matrix were refined due to the significant reduction of temperature and weak thermodynamic driving force. Especially, at an optimal v of 800 mm/s, a microhardness of 369.5 HV0.2, ultimate strength (σb) of 1030.5 MPa and elongation (δ) of 26.92% were obtained. The excellent performances were benefited from the high densification, uniform microstructures and nano reinforcements.