Simulating cast-like microstructure using laser powder directed energy deposition (LP-DED) – a critical step to enable LP-DED as a high-throughput screening tool for conventional Al alloy development

Laser powder directed energy deposition (LP-DED) additive manufacturing (AM) has been proposed as a high-throughput tool to support combinatorial alloy synthesis. However, this approach cannot directly inform alloy development for traditional cast and wrought Al alloys due to vastly different microstructure and mechanical properties from the laser produced materials. In the present work, we propose a new manufacturing route of LP-DED to simulate cast-like microstructure of Al-Mn-Fe-Si alloy made by direct chill (DC) casting. By utilizing substrate heating and grain refinement, the optimized LP-DED alloy exhibited similar microstructure and mechanical response as DC-cast counterpart, under both as-built and homogenization conditions. The alloy also showed similar recrystallization dynamics and microstructure as DC-cast alloy under the same thermomechanical treatment. The results showed that the optimized LP-DED process can produce materials that share the similar microstructural characteristics and properties as its DC-cast counterpart. This method bridges the gap between laser AM and conventional casting processes, and for the first time makes LP-DED a feasible high-throughput screening tool for DC-cast Al alloy development.