Study of order—disorder transformation of copper—gold alloys by means of differential thermal analysis

Several copper-gold alloys, with compositions of between 10 and 80 atomic percent of gold, were examined by quantitative DTA from 25 to 500°C. The results are in good agreement with those obtained by other less rapid, but more accurate, methods. All the reactions observed were first-order transformations. A latent heat (180 ± 40 cal g-at^?1) was measured at 405°C for the α″_I → α″_II transformation of the alloy containing 50% of gold. An endothermic effect, corresponding to an order—disorder reaction, was detected for all alloys, up to a composition of over 90 atomic percent of gold.