INVITED: Solidification and microstructural evolution in additively manufactured metallic alloys

Metallic alloys with high printability and superior properties are desired to be used in additive manufacturing (AM), e.g., laser powder bed fusion (LPBF). Understanding the phase equilibrium and microstructural evolution is essential to the development of AM-specific alloys. Two strategies toward developing printable aluminum alloys are presented and examined using several modeled alloys. The first approach is to in-situ refine the grain structures upon solidification, as demonstrated by LPBF Zr/Sc modified aluminum alloys. The effect of Zr/Sc on solidification and microstructure is revealed by comparing to the LPBF conventional aluminum alloys that exhibited solidification cracks. The second approach is to utilize the eutectic aluminum compositions with minimum solidification range, as demonstrated by AlSi10Mg and Al-10Ce alloys. Post heat treatment is applied to the as-printed alloys to tailor the microstructure and optimize the mechanical property. Effectiveness of the strategies is verified by the outstanding tensile property compared to the conventional counterpart.