Accelerating design for additive manufacturing: Experimental investigation and theoretical assessment on microstructure evolution of Al-Yb alloy

Eutectic systems are widely used in additive manufacturing to suppress hot tearing, despite their unsatisfactory mechanical properties. The Al-Yb system demonstrates exceptional potential for high-strength aluminum alloys due to its coherent eutectic/matrix interface and superior age-hardening response. Given the paucity of systematic investigations in Al-Yb system, a detailed investigation of its microstructure under rapid solidification is crucial for accelerating its development. This investigation systematically evaluates the potential microstructure of the compositional-process space via single-track laser remelting experiments. By optimizing the phase-competitive growth model based on non-linear phase diagram, the eutectic coupling zone and the morphology of primary Al and eutectic structure are quantitatively discussed using the experimental results as inputs and corrections. During the process, a new divorced eutectic criterion is proposed by coupling the dendrite and eutectic growth models, suggesting that eutectic Al grows epitaxially on primary Al and the eutectic Al₃Yb phase exhibits complete segregation when the intercellular spacing is equal to the eutectic lamellar spacing. These discoveries are comprehensively mapped within a three-dimensional composition-growth velocity-temperature gradient (C₀-V-G) microstructural selection framework. The proposed methodology provides transformative insights for accelerating alloy development cycles through computational-experimental co-optimization of composition and processing parameters in Al-Yb systems.