Positioning of interstitial carbon atoms in the deformed Fe-C system

Y Yang and XQ Ou and H Zhang and M Song, MATERIALS TODAY COMMUNICATIONS, 34, 105377 (2023).

DOI: 10.1016/j.mtcomm.2023.105377

As a principal alloying element, carbon plays a key role in enhancing the mechanical properties of steels. Understanding the interstitial sites occupied by carbon atoms is crucially important to grasp the corresponding solution strengthening mechanism even when phase transformation occurs. However, the interstitial sites in crystals are difficult to observe experimentally, especially during the transformations that happen with a very high speed. Here on the basis of previous first-principles calculations, the interstitial sites for carbon atoms in different phases during deformation-induced phase transformations in Fe-C alloys are investigated by molecular dynamics simulations, which enables the observation of the microstructural evolution at the atomic scale and also the calculation of the energy of the systems. Carbon atoms are found to have a specific distribution among the Fe lattice and this can be changed when loading from another direction. The formation energies of the interstitial sites indicate that carbon atoms can not only locate at the most stable octahedral interstitial sites, but also can occupy the interstitial sites with relatively higher formation energies during phase transformations. A specific arrangement of carbon atoms can lead to the formation of stacking faults during the BCC & RARR;HCP phase transformation. Further, carbon atoms at different interstitial sites of the BCC structure have varied pinning effects on the movement of dislocations.

Return to Publications page