Deformed Microstructure in Room Temperature Ductile Nb₂Co₇ Intermetallic Compound

Intermetallic compounds exhibit superior strength at elevated temperatures, but they are generally brittle at room temperature, leading to widespread efforts to improve their plasticity for practical applications. Recently, Nb₂Co₇, an intermetallic compound with a layered structure, has attracted attention because of its plastic deformability even at room temperature [1]. In this work, we have investigated a microscopic deformation mechanism of layered Nb₂Co₇ compounds based on electron microscopy observations and first-principles calculations. Transmission electron microscopy (TEM) observations revealed that the deformation of Nb₂Co₇ is mainly carried out by basal dislocations localized between the close-packed (CP) layer. In addition, dislocations with the same signs are aligned to form boundaries with small angle misorientations, termed kink boundaries. A combination of atomic-resolution observations and theoretical calculations demonstrates that the microscopic deformation process is accompanied by partial dislocations with stacking faults and that partial dislocations with specific variants significantly reduce the activation energy of shear deformation.<br/><br/>Reference<br/>[1] L. Siggelkow et al, MSEA 497 (2008) 174–180.