Calorimetric Investigation of the Cu3Au Alloy Above the Critical Temperature

Abstract

The amount of heat released in a Cu3Au sample, while undergoing an incremental decrease of 50°C in temperature, has been measured at several temperatures. Apart from the sharp maximum at the critical temperature, the heat release does not decrease monotonically with increasing temperature, as predicted by the theory of the short-range order: it goes up to a maximum at about 600°C. The heat release at the maximum is 1% of the value obtained at the critical temperature.

A structural study of the alloy Cu3Au above its critical temperature

“…Thus there is no information very close to Tc, nor does the available data extend over the entire temperature range. Yet measurements in the literature indicate anomalies in specific heat (Kuczynski, Doyama & Fine, 1956;Guarini & Schiavini, 1965) and other properties (Damask, Fuhrman & Germagnoli, 1961;Benci, Gasparrini & Germagnoli, 1964;Feder & No-wick, 1955;Dugdale, 1956;Schfile, 1957) at approximately 600 and 850°C. While these have been questioned by Hirabayashi, Nagasaki and Kono (1957), who suggested that the effects were due to quenching, they used a much faster heating rate than the others; the sheer body of evidence by several workers whose data was taken at high temperatures strongly suggests that there may well be some abrupt changes in the solid solution, rather than just a steady decrease in short-range order with increasing temperature above Tc.…”