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The paper presents a study of the phase selection and microstructure evolution of Fe75B25 alloy subjected to solidification at various undercoolings. The alloy invariably solidifies into a primary Fe2B phase and α-Fe/Fe2B eutectic at all the experimental undercoolings up to 381 K. A metastable Fe3B phase does not precipitate, although its growth in this alloy is favored without large-scale solute diffusion involved. It is shown that the phase selection is nucleation-controlled. Solid sites existing in the alloy melt seem more favorable for the nucleation of the Fe2B phase. As undercooling increases, primary the Fe2B phase changes its morphology complexly. It solidifies into coarse faceted dendrites at low undercoolings, developed non-faceted dendrites at moderate undercoolings, seaweeds with dense branches at higher undercoolings, and refined granular grains at undercooling above 147 K.

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Subcortical brain regions play essential roles in the onset of social anxiety disorder (SAD). While adolescence is the peak period of SAD, the relationships between abnormal development of the subcortical regions during this period and SAD are still unclear. This study investigated the agedependent alterations in structural co-variance among subcortical regions and between subcortical and cortical regions, aiming to re ect aberrant coordination during development in adolescents with SAD.High-resolution T1-weighted images were obtained from 76 adolescents with SAD and 67 healthy controls (HC), ranging from 11.0 to 17.9 years. We found that the SAD group exhibited signi cantly enhanced structural co-variance among key striatum regions (putamen and caudate). While the covariance decreased with age in healthy adolescents, the co-variance in SAD adolescents stayed high, leading to more apparent abnormalities in middle adolescence. Moreover, the striatum's mean structural co-variance with cortical regions decreased with age in HC but increased with age in SAD. The agedependence of the abnormal coordination indicates atypical developmental trajectories of the striatum and its balance with the cortical regions in adolescents with SAD.