代位原子在Fe3Al亚点阵中的占位与合金的塑性

采用中子衍射法测定了Ｃｒ、Ｍｏ、Ｔｉ、Ｎｉ、Ｍｎ、Ｓｉ等代位原子在ＤＯ３结构Ｆｅ３Ａｌ亚点阵中的原子占位，并从解离能角度探讨了原子对之间的相互作用及合金室温塑性的影响，结果表明：Ｃｒ、ＭＯ、Ｔｉ都占据了Ａｌ原子的次近邻位置，替代Ｆｅ原子；Ｎｉ、Ｍｎ占据Ａｌ原子的最近邻位置，（Ｓｉ＋Ａ）当量成分以内的Ｓｉ原子替代占据Ａｌ原子的位置，由于Ａｌ－Ｃｒ原子对的结合能低于Ｆｅ－Ａｌ，ＡＬ－Ｍｏ用Ａｌ－Ｔｉ对

SITE OCCUPATION OF SUBSTITUTIONAL ATOMS IN Fe_3Al SUBLATTICE AND DUCTILITY OF ALLOYS

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.