An alternate approach for estimating grain-growth kinetics

Rate of grain growth, which aides in achieving desired properties in polycrystalline materials, is conventionally estimated by measuring the size of grains and tracking its change in micrographs reflecting the temporal evolution. Techniques adopting this conventional approach demand an absolute distinction between the grains and the interface separating them to yield an accurate result. Edge-detection, segmentation and other deep-learning algorithms are increasingly adopted to expose the network of boundaries and the associated grains precisely. An alternate approach for measuring grain-growth kinetics, that curtails the need for advanced image-processing treatment, is presented in this work. Grain-growth rate in the current technique is ascertained by \textit{counting} the number of triple-( and quadruple-) junctions, and monitoring its change during the microstructural evolution. The shifted focus of this junction-based treatment minimises the significance of a well-defined grain-boundary network, and consequently, the involvement of the sophisticated techniques that expose them. A regression-based object-detection algorithm is extended to realise, and count, the number of junctions in polycrystalline microstructures. By examining the change in the number of junctions with time, the growth rate is subsequently determined.Growth kinetics estimated by the present junction-based approach, across a wide-range of multiphase polycrystalline microstructures, agree convincingly with the outcomes of the conventional treatment.Besides offering a novel technique for grain-growth measurement, the analysis accompanying the current work unravels a trend, compatible with the topological events, in the progressive evolution of the triple-junctions count. The present approach, through its underlying algorithm, provides a promising option for monitoring grain-growth during in-situ investigations.

Manoj Prabakar, P G Kubendran Amos · 2024