纯铁离子渗氮扩散层中α″→γ′氮化物的转变

INVESTIGATION ON α"→γ′ NITRIDE TRANSFOR-MATION IN THE DIFFUSION LAER OF ION-NITRIDED PURE IRON

利用透射电子显微镜对纯铁离子渗氮扩散层中的γ′－Ｆｅ４Ｎ氮化物进行微观分析时发现，组织中存在两种类型的γ′－Ｆｅ４Ｎ 通过其内部是否含有高密度的单方向平行层错片可以将二者区分开来、实验中观察到了直接生长在α″－Ｆｅ１６Ｎ２上的 γ′－Ｆｅ４Ｎ氮化物，证实组织中存在α″→γ′氮化物的转变．通过此氮化物转变生成的γ′－Ｆｅ４Ｎ，其内部含有单方向排列的平行层错片，根据 α″－Ｆｅ１６Ｎ２和γ′－Ｆｅ４Ｎ的晶体结构讨论了氮化物转变的结构条件，转变过程中二者保持如下的取向关系：（１１１）γ′／／（１１０）α″，［１１０］γ′／／［１１１］α″．

Two kinds of γ'-Fe4N nitrides precipitated from the diffusion layer of ion-nitrided pure iron during the furnace cooling process. One kind is full of finely spaced parallel striations, which are identified as stocking faults, while the other does not have such parallel stacking faults. α''→γ' nitride transformation was directly observed in the diffusion layer, which gives definite evidence for the in situ nucleation of γ'-Fe4N on α'－Ｆe16N2 nitride. The interior of the γ'-Fe4N nitride transformed from α'-Fel6N2 nitride has parallel stacking faults. This nitride transformation was discussed according to their crystal structures. There is a orientation relationship of (111)γ' // (110)α', [110]γ' // [111]α' during the transformation.