Microscopic phase-field study on aging behavior of Ni_(75)Al_(17)Zn_8 alloy

The precipitating kinetics of Ni75Al17Zn8 alloy was studied at both 873K and 973K by microscopic phase-field model. The calculation results show that the order-disorder transformation experiences the matrix → lowly-ordered L10 phase → L12 phase at 973 K. And the nucleation of L12 particles belongs to the spinodal decomposition mechanism. As temperature increases, orderings of Al and Zn atoms are resisted, but coarsening of L12 particles is promoted. The value of coarsening kinetic exponents approaches to 1/2. In addition, the discussions about Ni-Al anti-site defect and Zn substitutions for Ni site and Al site exhibit that the higher the temperature, the more distinctive the Ni-Al anti-site defect, but the less the Zn substitution.