Time-evolution of L10-type ordering in CuAuPd ternary alloys at 573 K has been studied in terms of change in long-range order (LRO) parameters Si's determined experimentally by an electron diffraction technique IKL-ALCHEMI. The results clearly show that the ordering rates are different among the three elements. In alloys of Cu50Au35Pd15 and Cu50Au25Pd25, the LRO parameters of three elements Si's are enhanced monotonically with time, showing inequality |SAu| > |SCu| > |SPd| in the early stage, but |SPd| ≥ |SCu| ≥ |SAu| in the late stage. When the Cu content deviates from 50 at% to 45 at%, such as in Cu45Au40Pd15 and Cu45Au40Pd15, SAu once increases and then slightly decreases after reaching a peak, while SPd and SCu continuously approach the equilibrium values. The overshooting of SAu disappears in a less Cu-content alloy of Cu42.5Au42.5Pd15. The master equation approach has been employed to understand the kinetic behavior as a function of the ordering energies Vij's, the mobilities of atoms Wi's and alloy composition. The ordering kinetics in CuAuPd alloys is thoroughly explained in terms of VCuPd > VCuAu > VAuPd, and WCu, WAu > WPd.
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