Metal powder bed thermal diffusivity and effects of gas environments on powder flow

A laser flash tri-layered analysis for measuring the thermal diffusivity of nickel-based superalloy Inconel718 (IN718), in laser powder bed fusion (LPBF) additive manufacturing is described. Thermal diffusivities of IN718 powder from two different vendors in two separate gaseous environments (He and N₂) inside the furnace were measured at different temperatures (200 °C, 400 °C, 600 °C). Measurements indicate that the thermal diffusivity of IN718 is nearly independent of the change in temperature and vendor while it is influenced critically by the change in gaseous environment. Thermal diffusivity also changes as a function of powder bed thickness. Thermal diffusivity of solid IN718 was measured to observe the comparison between solid and powder thermal diffusivities. This work also includes simulation using a commercial additive manufacturing simulation software to replicate the powder bed spreading and melting in LPBF and to observe the spreading and melting behavior of powder bed.