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Revealing mechanisms of dynamic recrystallization during laser directed energy deposition of high-entropy Cantor alloy by multimodal melt pool monitoring
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DOI：10.1080/17452759.2026.2711469.png)
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Abstract
En 中文
Physics-informed grain structure engineering in fusion-based laser additive manufacturing offers great promise for producing high-performance high-entropy alloys, especially for low-cost and compositionally-customized laser directed energy deposition (DED). However, detrimental columnar grains prevalently form in DED due to relatively low solidification rates and extremely high temperature gradients, making them difficult to disrupt and still poorly understood. Here, combining in-situ high-speed synchrotron X-ray imaging and diffraction, thermal imaging, and ex-situ electron microscopy approaches, we reveal a dynamic recrystallization (DRX) mechanism associated with the disruption of epitaxial columnar grains during DED of an exemplary high-entropy Cantor alloy. Multimodal melt pool monitoring enables quantitative analysis of solidification parameters and melt flow characteristics with high temporospatial resolution. Experimental observations combined with thermo-kinetic calculations indicate that both intragranular and intergranular DRX can be activated by localised micro-strains. DRX promotes grain refinement and homogeneity by tailoring energy input with optimally increasing laser power and reducing scan speed, and contributes to a tensile-to-compressive strain reversal during real-time deposition. The results of solidification-dependent grain structure evolution down to melt pool scale provide deeper understanding of in-process grain growth kinetics and enable effective methods for disrupting columnar grain growth during DED processing of novel alloys.
Keywords:
Grain growth dynamics
directed energy deposition
high-speed synchrotron X-ray imaging and diffraction
high-entropy cantor alloy
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