马氏体相变时原子的位移

Atomic Displacement Mode During the Martensitic Transformation

理论地综合分析了奥氏体转变为马氏体过程中原子的移动方式。奥氏体转变为马氏体时,在相变驱动力的作用下,原子主要是按照K-S位向关系从奥氏体晶格中直接转移到马氏体晶格上去的。当γ→α马氏体时,以晶体缺陷为起点出现涨落,原子无扩散,集体协同位移,进行了菱形参数的调整,完成了γfcc→αbcc-M的晶格重构。原子移动距离远远小于一个原子间距,比K-S切变位移小1个数量级,耗能少。γ→α转变产生应变能。为了调整应变能和适应晶格匹配,形成相变位错、层错或相变孪晶等缺陷,以完成马氏体转变。

The atomic displacement mode during the transformation from austenite to martensite was synthetically analyzed theoretically. During the transformation, the atoms mainly directly shift from austenitic lattice to martensite lattice according to the K-S orientation relationship under the action of the phase transformation driving force. When γ, transforms to α, the fluctuations first appear in the crystal defects, then the atoms shift by the way of the collective collaborative displacement without diffusion making the adjustment of rhombic parameters. Thus completes the lattice reconstruction from γfcc to αbcc-M. The atomic displacement distance in this mode is much smaller than an atomic spacing, which is smaller than that in the shear displacement an order of magnitude, so it consumes energy smaller. Since the strain energy emerges in the transformation of γ→α, the substructure of the dislocation, stacking fault or twin crystal can form to adiust the strain energy.