Mechanical response of carbon ion implanted ferrite via atomic simulations

Abstract

Ion implantation plays a nontrivial role in improving the mechanical properties of materials. Unfortunately, the atomic-scale understanding and awareness of the improvement mechanisms remain insufficiently clear and accurate. This paper investigates the nanostructural evolution of carbon ion implanted ferrite and the mechanical response under uniaxial tension leveraging molecular dynamics (MD) simulation, providing direct atomic-scale evidence of alloy strengthening. Regarding nanostructural evolution, grain boundary migration induced by carbon ion implantation becomes significant with increasing doses. However, point defects and amorphous structures caused by collision cascades tend to saturate gradually with increasing implantation doses. Uniaxial tensile test results indicate that the strength of all ion-implanted samples is appreciably enhanced compared to non-implanted samples, especially with an implantation dose of 6.23 × 10¹³ ions/cm², where the strength increases by 39%. The underlying strengthening mechanism is that defects, amorphous structures, and lattice distortions induced by ion implantation collectively act as formidable barriers to dislocation motion during plastic deformation, strongly governing dislocation propagation and multiplication. More importantly, the interaction between carbon atoms from ion implantation and dislocations renders the formation of Cottrell atmospheres, which further enhances solid solution strengthening by pinning dislocations. These results advancing the fundamental understanding of nanostructural evolution and strengthening mechanism under ion implantation suggest a mechanistic strategy for augmenting alloy strength.