Multi-dimensional quantitative analysis of precipitates in the hot-rolled Al-1%Mn alloy

Precipitates formed during the hot-rolling process of Al-1%Mn alloy were quantitatively characterized by 3-dimensional (3-D) evaluation. The 3-D image was reconstructed using a serial sectioning technique by combining the focused ion beam and scanning electron microscopy (SEM). In the reconstructed 3-D volume, more than 10000 precipitates were extracted, and the log-normal distribution explained the size distribution well. We also quantitatively evaluated the precipitates from the 2-dimensional (2-D) SEM image taken during the serial-sectioning and from the scanning transmission electron microscopy (STEM) observation that the specimen was fabricated from the serial-sectioned sample. According to the data evaluated from the 2-D and the 3-D images, the average size of the precipitation measured by the 3-D image was larger than that of the 2-D images of SEM and STEM. That is presumed by the morphological anisotropy owing to hot rolling. We also discussed the effect of the number of the analyzed precipitates on the average size and distribution. The average size significantly depends on the number of analyzed precipitates. Besides, we evaluated the normality of the logarithmic distribution of the size by the Quantile-Quantile plot.