Fe－C马氏体室温时效转变的研究Ⅱ－调幅分解

AGING OF Fe-C MARTENSITE Ⅱ─SPINODAL DECOMPOSITION

采用马氏体漫散射的Ｆｏｕｒｉｅｒ分析方法并与显微组织分析相结合，确认Ｆｅ－ｌ．８３Ｃ％（质量）马氏体在时效时发生了调幅分解，其调幅结构由波长为１ｎｍ左右的主波和大于１ｎｍ的次波叠加而成．首次发现铁碳马氏体调幅分解存在一个显著的特点，即调幅结构即使在长达数月之后也未发生长大，其原因是贫富碳区之间的强烈弹性交互作用使得处于分解早期的调幅结构的长大陷于停止，最后，提出了一个重要的问题，即铁碳马氏体中存在的有序化和调幅分解共存的现象对经典的相变理论提出了重大挑战．经典相变理论无法解释有序化与调幅分解共在现象的原因，在于它建立在过于简单的原子最近邻作用假设之上。

This paper deals with the spinodal decomposition of Fe-1.83C martensite during agingat room temperature. Spinodal mechanism is confirmed by using Fourier analysis of diffusescattering from martensite and direct microstructural analysis.It is found that the modulatedstructure is composed of dominant wave of about 1 nm and non-dominant wave of longerwaves.For the first time it is found that the modulated structure of Fe-1.83C martensitedoes not grow even after aging for several months,this is due to the strong elastic interac-tions among carbon enriched and depleted regions prohibiting the further growth of the spin-odal products.The coexistence of ordering and spinodal decomposition found in this studyappears to be a great challenge to the classical theory of phase transformation,and the fail-ure of classical theory in explaining the coexistence of ordering and spinodal decomposition is due to its over-simplified nearest neighbor atomic interaction hypothesis.