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结合Fe-Mn-Si合金中马氏体的相变特点提出一种新的序参量——层错密度,相应建立了马氏体相变的Landau理论.利用这种理论对现有的马氏体相变机制进行了合理的解释,并加以推论,提出一种更为细致的相变机制:层错由不规则堆垛到一种规则堆垛,再经过不规则阶段进行到另外一种规则堆垛,如此循环下去,直到某一温度下的稳定结构.这种机制明确地描述了马氏体的形核及其转变过程.界面可作为孤立子来进行考虑,并将它同序参量联系起来.界面孤立子的作用是完成马氏体不同类型的转变,其运动速度可以借助层错密度的变化率来表达.利用这一序参量合理解释了训练和外界应力对相交点的影响原因,训练改变了层错的堆垛周期,层错密度增加,相变点升高;外界应力使相变点提高.基于这种自由能函数,建立了母相到过渡相的相变热力学,以及过渡相间的转化热力学.
Based on the phase transformation of martensite in Fe-Mn-Si alloy, a new order parameter-layer fault density is proposed, and Landau’s theory of martensitic transformation is established accordingly.Using this theory, Reasonable explanation of the body-phase transformation mechanism is made and deduced. A more detailed phase-change mechanism is proposed: the stacking fault from irregular stacking to a regular stacking, and then to another rule through the irregular phase Stacking, and so on until a stable structure at a certain temperature.This mechanism clearly describes the martensite nucleation and its transformation process.The interface can be considered as a soliton, and it is connected with the order parameter The role of the interface soliton is to complete the different types of martensitic transformation, the velocity of which can be expressed by the rate of change of fault density.Using this sequence parameter reasonably explained the reason of the impact of training and external stress on the intersection point, Training changed the stack stacking cycle, the stacking fault density increased, the transformation point increased, and the external stress increased the transformation point.Based on this free energy function, the phase transition thermodynamics of the parent phase to the transition phase were established, and the transition Phase transformation thermodynamics.