Thermodynamics-guided alloy and process design for additive manufacturing

In conventional processing, metals go through multiple manufacturing steps including casting, plastic deformation, and heat treatment to achieve the desired property. In contrast, additive manufacturing (AM) requires achieving similar properties in a single fabrication process involving solidification and cyclic remelting. This study addresses the thermal and kinetic differences between solid and liquid phases, which can lead to defects such as hot cracking due to constitutional undercooling and local variations in the solidification interval. We present a thermodynamics-guided approach to solving the hot cracking problem, using IN738LC superalloy as a model material. The findings reveal that the unique challenges presented by AM, notably high cooling rates and solute trapping, require tailored alloy designs that account for these rapid solidification dynamics, providing insights applicable to other alloy systems susceptible to hot cracking. This research contributes to the understanding of material heterogeneity and mechanical properties in metal 3D printing, promoting advances in the field of additive manufacturing.