Ab initio study of I2 and T2 stacking faults in C14 Laves phase MgZn2

Based on the synchroshear mechanism, the formation of intrinsic stacking fault I-2 and twin-like stacking fault T-2 in C14 Laves phases has been modeled in detail and the generalised stacking fault energy curve of I-2 and T-2 for C14 Laves phase MgZn2 has been calculated from first-principles. The results demonstrate that the unstable stacking fault energy of I-2 by synchroshear is still very large, and the stable stacking fault energy of I-2 is higher in comparison with pure Mg implying that the formation of I-2 stacking fault in MgZn2 is difficult. Starting with the I-2 configuration, the T-2 stacking fault can be formed by an additional synchroshear. The unstable and stable stacking fault energies of T-2 are only slightly larger than those of I-2, implying that the formation of T-2 may be essentially similar to that of I-2. From the obtained generalised stacking fault energy, the relevant deformation mechanism of MgZn2 is also discussed. Finally, the electronic structure during synchroshear process is further studied.