Atomistic investigation into the mechanical properties of the ferrite-cementite interface: The Bagaryatskii orientation

Abstract Atomistic modeling is used to investigate the mechanical response to compressive and tensile straining of the Bagaryatskii orientation relationship between ferrite and cementite within pearlite. A range of interlamellar spacings and ferrite to cementite ratios are considered and values for important mechanical properties, including elastic modulus, yield stress, flow stress, and ductility, are determined. These values are fit to simple elasto-plastic models, thus allowing for the easy interpolation of states not simulated. Transverse loading can be described using simple 1-D composite theory, while longitudinal loading requires the consideration of the strain compatibility of the interface. The mechanical properties are shown to be largely dependent on the volume ratios of the cementite and ferrite, with the interlamellar spacing having an increasing role as it reaches smaller values. Additionally, the effect of the interface is discussed and characterized, including its role as a nucleation site for dislocations in both the ferrite and cementite.