Cell Area Characterisation of Fe-B-C Cast Alloys with Various Additions of Cr, V, W, Ti, Nb and Mo Measured by Optical Microscopy Method

This study developed an automated workflow for spatially resolved quantitative characterisation of Fe–B–C alloy microstructures across sample cross-sections. Automated high-magnification optical microscopy and image reconstruction generated spatially registered maps exceeding 20 GB per sample, preserving microstructural detail and spatial position. The workflow quantified cell area and core-to-surface gradients, while the maps supported assessment of boride-network distribution and morphology. It was applied to 22 hypoeutectic alloys containing approximately 0.35 wt.% B, prepared under identical casting conditions, and modified with Cr, V, W, Ti, Nb, and Mo. Optical emission spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy complemented full-area image analysis and statistical evaluation. After invalid measurements and geometrically unsuitable regions were excluded, 12,785 figures with valid cell area measurements were analysed. All alloys exhibited a decrease in cell area from the core towards the surface. Alloy-group differences were significant for mean and median cell area according to one-way analysis of variance (ANOVA; p < 0.001) and the Kruskal–Wallis test (p = 0.027 for both parameters), whereas the magnitude of the spatial gradient did not differ significantly among groups. The workflow provides a reproducible link between high-resolution microscopy and sample-scale evaluation of microstructural distributions, gradients, and homogeneity.