A molecular dynamics study of dislocation-interphase boundary interactions in FCC/BCC phase transformation system

Abstract

Industrial alloys are often strengthened via the formation of second phase during phase transformation due to the strong barrier of the interfaces between the second phase and the matrix, or interphase boundaries (IPBs), for dislocation propagation. In the present work, molecular dynamics simulation was employed to reveal the atomistic processes of the interactions between the lattice dislocations and face-center-cubic (FCC)/body-center-cubic (BCC) IPBs, including the image force on the lattice dislocation, slip transmission and other local reactions between the lattice dislocation and interfacial dislocations. It is found that the image force always attracts BCC lattice dislocation towards the IPB due to the difference in elastic properties of the two phases. With the presence of external force, four dislocation/IPB interaction results were observed among various dislocation-IPB interactions. Detailed analysis were made regarding how influencing factors such as resolved shear stress, continuity of slip systems, local dislocation reaction and dislocation core spread, affect dislocation-IPB interaction results. The present work provides some new insight into an in-depth understanding of how and in what ways IPBs can affect the plastic deformation in alloy systems.