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Ｆｅ－１．８３Ｃ马氏体在室温时效时，超点阵衍射斑点发生分裂，表明产生了长周期有序相。分析确定该相由普通有序相γ′—ＦｅｘＣ（Ⅰ）衍生而来，周期为１０ｃ＿Ｍ（ｃ＿Ｍ为马氏体ｃ轴的长度），称为γ′—ＦｅｘＣ（Ⅱ）（ｘ＝４—１０）．其周期不随时效时间变化，但随温度升高而增加。超点阵斑点的分裂距离所对应的长周期不是ｃ＿Ｍ的整数倍，表明周期为１０ｃ＿Ｍ，１２ｃ＿Ｍ，１４ｃ＿Ｍ的３种长周期有序结构可能同时存在，其衍射线互相干涉使超点阵斑点的分裂距离不为ｃ＿Ｍ的整数分之一。根据本研究确定的长周期有序相的晶体结构，计算出的电子衍射强度与实验观测值完全符合。本文还讨论了普通有序相γ′—ＦｅｘＣ（Ⅰ）与长周期有序相γ′—ＦｅｘＣ（Ⅱ）的相互关系。
At room temperature for the Fe-1.83C martensite, the superlattice diffraction spots were split, indicating that a long period ordered phase was produced. The phase is derived from the normally ordered phase γ’-FexC (Ⅰ) and has a period of 10c_M (c_M is the length of the c-axis of the martensite) and is called γ’-FexC (II) (x = 4-10 ). The cycle does not change with the aging time, but increases with increasing temperature. The long period corresponding to the splitting distance of the superlattice spot is not an integral multiple of c_M, indicating that three kinds of long period ordered structures with periods of 10c_M, 12c_M and 14c_M may coexist. The diffraction lines interfere with each other to split the superlattice spots The distance is not a fraction of an integer c_M. Based on the crystal structure of the long-period ordered phase determined in this study, the calculated electron diffraction intensities are in good agreement with the experimental observations. We also discuss the relationship between the regular ordered γ’-FexC (Ⅰ) and long-period ordered γ’-FexC (Ⅱ).