The kinetics of atomic ordering in a series of alloys in the
Pt1Co1−xNix ternary system where
0<x<0.5 were investigated by magnetic measurements. For all the
alloys, the ordering kinetics as monitored by the saturation magnetization
as a function of isothermal ordering time at a series of specified ordering
temperatures, were found to be exponentially time dependent. The associated
time constant was found to have an Arrhenius temperature dependence
characterized by an activation energy that, with increasing nickel
concentration, initially increased to maximum value at a nickel composition
of x ∼.2 and then systematically decreased. This result for the activation
energy as a function of nickel content was found to correlate roughly with
the behavior of the saturation magnetization of the ordered alloys,
suggesting that the kinetics of the transformation in this alloy system is
sensitive to the magnetic properties of the ordered state.