Ab initio study of stacking faults and deformation mechanism in C15 Laves phases Cr2X (X = Nb,Zr, Hf)

Based on the synchroshear model, the formation of stacking fault and twinning fault in C15 Laves phases is modeled, then the generalized stacking fault energy curves and deformation mechanism in C15 Laves phases Cr₂X (X = Nb, Zr, Hf) alloys are investigated by ab initio calculations based on the density functional theory. The results demonstrate that the unstable stacking fault and twinning fault energies of C15 Laves phases Cr₂X (X = Nb, Zr, Hf) by the synchroshear are still large while the stable stacking fault and twinning fault energies are low, and the deformation modes by extended partial dislocation and twining are feasible in C15 Laves phases Cr₂X (X = Nb, Zr, Hf). Moreover, the Cr₂Nb has the largest deformation twinning tendency, followed by Cr₂Zr and Cr₂Hf. The evolution of electronic structure during the synchroshear process is further studied to unveil the intrinsic mechanism for the formation of stacking fault and twinning fault in C15 Laves phases Cr₂X (X = Nb, Zr, Hf).