Monte Carlo study of ordering processes in fcc-based Ni-Mo alloys

The Monte Carlo simulations were carried out to clarify the ordering mechanisms in fcc-based Ni-Mo alloys of Ni₄Mo, Ni₃Mo and Ni₂Mo. When the pairwise atomic interactions up to the eighth coordinate shells are taken into account, the simulation results are consistent with the experimental changes in electron diffraction pattern during the ordering processes in Ni₄Mo, Ni₃Mo and Ni₂Mo alloys. In the early stage of ordering, subunit cell clusters of D1_a, D0₂₂ and Pt₂Mo structures are first generated to form the short range ordered (SRO) state. The selective growth of stable D1_a and/or Pt₂Mo-type ordered domains is involved in the transition to the long range ordered (LRO) state in the following stage.