Effects of rare earth elements doping on ordered structures and ductility improvement of Fe–6.5wt%Si alloy

Fe–6.5 wt%Si alloy's poor ductility is mainly caused by the large amount of brittle ordered structure, and the significant reduction of Fe–6.5 wt%Si alloy's order degree was found by rare earth elements (yttrium, lanthanum, cerium) doping, hence the average room temperature bending deflection increases to 0.77 mm from 0.62 mm and the average tensile elongation to failure at 400 °C increases to 23.0% from 7.3% by 0.021 wt% cerium doping. The order degree reduction phenomenon was manifested by the obvious decrease of B2 and D03 ordered structure reflection intensity in X-ray diffraction and selected area electron diffraction patterns and the ordered domains refinement in transmission electron microscopy. The rearrangement capability of adjacent atoms during order–disorder transformations is lowered due to the iron and silicon atoms are dragged by rare earth atoms, hence the formation of ordered phases is hindered, which provides a novel order degree reduction mechanism of Fe–6.5 wt%Si alloy.