SITE OCCUPATION OF SUBSTITUTIONAL ATOMS IN Fe_3Al SUBLATTICE AND DUCTILITY OF ALLOYS
代位原子在Fe3Al亚点阵中的占位与合金的塑性

The site occupation of substitutional atoms Cr, Mo, Ti, Ni, Mn, Si at sublattice in DO3 type stoichiometric Fe3Al intermetallics has been determined by means of neutron difractometry. On the basis of dissociation energy, the effect of atom interaction on the room temperature ductility is discussed. The experimental results indicate that Cr. Mo and Ti atoms all occupy the next nearest neighbour of Al atom, Ni and Mn atoms the nearest neighbour, while Si atom substitutes for the position of Al atom. Since the interaction energy of Al-Cr pair is lower than that of Fe-Al. Al-Mo and Al-Ti pair, the corresponding APB energy decreases and this explains why the addition of Cr improves the room temperature ductility of DO3 type Fe3Al intermetallics.