The disorder-order transition of FeCuPt nanoparticles with various Cu content

The effect of adding a third-element on disorder-order transition of FePt has been demonstrated using FeCuPt alloy as a model. The introduction of Cu leads to an increase in the ordering degree, and a moderate amount of Cu enhancing the most. Density Functional Theory calculations indicate that the disorder-order transition in FePt is influenced by the ordering temperature and vacancy formation energy. FePtCu alloy with a moderate Cu content exhibits the lowest vacancy formation energy in the L1₀-phase, which promotes the atom diffusion during annealing and resulting in a higher ordering degree. This study summarizes the annealing temperature, time, and thermodynamic or kinetic conditions required to achieve L1₀-FePtX alloy with superior ordering degrees. The findings offer valuable insights for selecting suitable third-elements and annealing parameters to produce L1₀-FePtX alloy with enhanced ordering degrees.