Cr原子在Fe_3Al金属间化合物亚点阵中占位测定

SITE OCCUPATION OF Cr ATOMS AT SUBLATTICE IN Fe_3Al-BASED INTERMETALLICS

利用中子衍射方法确定了Ｃｒ原子在Ｄ０_３有序结构的Ｆｅ－２８Ａｌ一５Ｃｒ合金亚点阵中的占位．结果表明：Ｃｒ原子仅替代Ｆｅ原子的位置，并占位于与Ａｌ原子次近邻的亚点阵，由于次近邻反相畴界能的降低，该合金四分位错组态中次近邻反相畴界的宽度变大，从而使交滑移变得容易，材料的变形能力得到改善，这一分析已分别为本工作对合金拉伸试样的表面滑移线金相观察和位错组态的ＴＥＭ研究所证实．

Based on the fact that the scattering lengths of Fe and Cr atoms to neutron are quite different,the site occupation of Cr in D0_3 type Fe-28Al-5Cr alloy has been determined by means of neutron difractometry.The experimental results indicate that Cr atoms are only substituted for Fe atoms and occupy the sublattice of the next nearest neighbour of Al atoms.Decrease in NNNAPB energy leads widening of NNNAPB in the superlattice dislocation and,therefore,cross slip becomes easier and the deformation ability is improved.This is confirmed by the investigation of the surface slip line and dislocation configuration under optical and transmission electron microscope respectively.