Exploring atomic occupation of ternary alloy elements at L1₂-Ni₃Al sub-lattice

The Ni 3 Al phase of L1 2 crystal lattice is the most important strengthening phase for nickel-base super-alloy of an aero-engine. The configuration of atomic occupation of alloy elements at the L1 2 -Ni 3 Al sub-lattice plays a key role in its serving properties in the thermal-mechanic condition. Through establishing the phase-field model of a ternary alloy system and solving the micro-diffusion dynamic functions, the spatial-temporal information on the atomic occupation of different L1 2 -Ni 3 Al sub-lattices is tracked, the occupation capability of ternary alloy elements is assessed and the atomic density distribution at single-lattice points is obtained. The atomic occupation of Ni-Al-V and Ni-Al-Cr precipitation phases in the L1 2 -Ni 3 Al sub-lattice after the phase transformation path of FCC→L1 2 +D0 22 is studied. The results show that through the time-related order process, the atomic occupation removes the competitive growth in the homogeneous or heterogeneous phase in the early phase transformation and the random fluctuation that interface migration causes to the sub-lattices. The Ni 3 Al phase is in fact a compound metal alloy phase. The antisite and substitution site are the functions of the binary solute ratio. The addition of Cr and V has an obvious difference in affecting the antisite and substitution site in different sub-lattices, which is related to sub-lattice type, defect type and alloy element type.