Abstract
In the specific heat curve of Cu3Au ordered alloy, an unexpected bump is shown at about 320°C in addition to the order-disorder transition at 390°C. A similar anomaly has also been found in FeCo alloy at about 550°C, the origin of which is clarified by Yokoyama et al. We applied the same procedure as employed in FeCo alloy to Cu3Au alloy with a face-centered cubic structure and investigated in detail the disordering process by measurements of electrical resistivity. Changes in resistivity as a function of temperature at the heating rates, 2°C/min and 20°C/35 hr (very slow rate), were also obtained by applying Bragg-Williams’ equation for the rate of approach to the equilibrium state. The anomaly at about 320°C does not occur in the equilibrium state, and it is considered to be caused by the heating rate too high compared with the diffusion rate, just as in the case of FeCo alloy.
