Molecular dynamics simulation study on impact of interface chemistry on pearlite mechanical response

The molecular dynamics (MD) simulation method was adopted to explore impact of interface chemistry on pearlite mechanical response of Bagaryatskii orientation relationship between ferrite and cementite. By changing terminal surface types of cementite at ferrite-cementite interface, this study analyzed influence of interface chemistry on pearlite peak stress and plastic deformation behavior, as well as strain transmission between two phases (ferrite and cementite) during stretching process. Two horizontal directions parallel to pearlite interface were considered as loading directions respectively. The results show pearlite will experience inelastic deformation due to atomic slip in ferrite phase. When terminal surface of cementite at interface is FeC-Fe, the atomic slip in ferrite is the most difficult to occur, and inelastic deformation shall be suppressed. At this time, pearlite produces the largest peak stress. Types of terminal surface and loading direction will affect slip systems activated in ferrite. Stretching along 100 & theta; direction: for pearlite with Fe-FeC and Fe-Fe cementite terminal surfaces at interface, S1 ({112} 111) slip system in ferrite is activated. While terminal surface is FeC-Fe pearlite, what is activated is S2 slip system ({110} 111) in ferrite. Stretching along 010 & theta; direction: regardless of types of terminal surface, slip systems activated are Type S2. Compared with S1 slip system, activation of S2 slip system makes is easier for plastic deformation in ferrite to pass through ferrite-cementite interface to the cementite.