This study investigates the effect of C on the deformation mechanisms in Fe–C alloys by molecular dynamics simulations. In uniaxial tensile simulations, the face-centered-cubic (fcc) structures of Fe–C alloys undergo the following deformation processes: (i) fcc→body-centered-cubic (bcc) martensitic transformation, (ii) deformation of bcc phase, and (iii) bcc→hcp martensitic transformation, which are significantly influenced by the C concentration. For the low C concentrations (0–0.8 wt%) fcc phase, the fcc→bcc phase transformation accords a two-stage shear transformation mechanism based on the Bain model, the deformation mechanism of the bcc phase is the first migration of twinning structures and then elastic deformation, and the bcc→hcp phase transformation follows Burgers relations resulting from the shear of the bcc close-packed layers. However, for the fcc phase with high C concentrations (1.0–2.0 wt%), the fcc→bcc phase transformation follows a localized Bain transformation mechanism impeded by the C atoms, the bcc phase only experiences elastic deformation, and the bcc→hcp phase transformation also conforms to Burgers relations but become localized due to the addition of more C atoms. Because of the different phase transformation mechanisms between the high C and low C supercells, the dislocation generation mechanism is also different.

本研究通过分子动力学模拟研究了C对Fe–C合金变形机制的影响。在单轴拉伸模拟中，Fe-C合金的面心立方（fcc）结构经历以下变形过程：（i）fcc→体心立方（bcc）马氏体相变；（ii）bcc相变形， （iii）bcc→hcp马氏体转变，这受C浓度的影响很大。对于低碳浓度（0–0.8 wt％）的fcc相，fcc→bcc相变符合基于贝恩模型的两阶段剪切转变机制，bcc相的变形机制是孪生结构的首次迁移，然后进行弹性变形，并且bcc→hcp相变遵循由bcc紧密堆积层的剪切产生的Burgers关系。然而，对于高C浓度（1.0–2.0 wt％）的fcc相，fcc→bcc相变遵循受C原子阻碍的局部贝恩变换机理，bcc相仅经历弹性变形，bcc→hcp相变也符合Burgers关系，但由于添加了更多的C原子而变得局部化。由于高碳超级电池和低碳超级电池之间的相变机制不同，位错产生机制也不同。