Microstructure of PyC dominates interfacial shear failure in SiCf/SiC composites: From localized sliding to uniform plasticity

•SiCf/PyC interface models are established by a novel OA-oriented modelling method.•As the increase of OA of PyC, interfacial shear deformation behavior transforms from localized penetrating sliding into large-scale uniform plasticity.•Trade-off between domain dispersity and pore-like defects of PyC determines the shear strength of SiCf/PyC interface.•Amorphous carbon component weakens shear resistance of SiCf/PyC interface.•The shear strength of SiCf/PyC interface under the experimental strain rate scale can be approximated as 50–60 MPa by extrapolating the relationship between the shear strength and strain rate from the simulation scale.