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When a defect is a pathway to improve stability: a case study of the L12 Co3TM superlattice intrinsic stacking fault

Zhang, Ying, Li, Jinshan, Wang, William Yi, Li, Peixuan, Tang, Bin, Wang, Jun, Kou, Hongchao, Shang, Shunli, Wang, Yi, Kecskes, Laszlo J., Hui, Xidong, Feng, Qiang, Liu, Zi-Kui
Journal of materials science 2019 v.54 no.21 pp. 13609-13618
case studies, chromium, energy, iron, manganese, molybdenum, nickel, phase transition, platinum, rhenium, rhodium, ruthenium, solutes, superalloys, titanium, vanadium, zirconium
Effect of solutes of transition metals (TM = Cr, Fe, Hf, Mn, Mo, Nb, Ni, Pt, Rh, Ru, Re, Ta, Ti, V, W, Y and Zr) on the local phase transition between the L1₂ and D0₁₉ structures in superlattice intrinsic stacking fault (SISF) of Co₃TM has been investigated. All the models employed herein, i.e. (1) the SISF-containing supercell, (2) the axial nearest-neighbor Ising (ANNI) model, and (3) both the L1₂- and D0₁₉-containing (L1₂ + D0₁₉) supercell, yield the same result regarding the stability of SISF in L1₂-type Co₃TM. In the view of bonding charge density, the atomic and electronic basis of local D0₁₉ phase transition in the SISF fault layers of Co₃TM are revealed. Especially, the negative SISF energy predicted by the L1₂ + D0₁₉ model suggests that both the SISF fault layers (i.e. the local D0₁₉ structure) and the L12 phase of Co₃TM can be stabilized through a coupling interaction between the fault layers and the solutes, paving a pathway to stabilize Co-base superalloys via Co₃TM precipitate. Moreover, the consist results of ESISF via the ANNI model with the classical SISF-supercell method utilized in first-principles calculations supports the approach to efficiently distinguish various planar faults and predict their corresponding energies, such as SISF, superlattice intrinsic stacking fault, anti-phase boundaries, and so on.