Phase equilibria in the Cu-rich portion of the Cu-Al binary system

The phase equilibria in the Cu-Al binary system over the temperature range 500 similar to 1000 degrees C and the composition range 15-60 at. % Al have been determined using diffusion couple technique, differential scanning calorimetry (DSC) and high temperature X-ray diffraction (XRD) methods. While the results from this study pertaining to the phase equilibria alpha/beta and epsilon(1)(epsilon(2))/liquid are in agreement with those reported in previous works, significant differences have been found between the earlier results and the present work in the composition range 25 similar to 40 at.% Al. They are: (a) In the composition range 32 similar to 38 at.% Al only a second order reaction, gamma(1)(D8(3)) --> gamma(0) (D8(2)), is seen to occur and not a two-phase equilibrium gamma(0)/gamma(1) reaction as reported before (b) The beta(0) phase is absent at high temperature near 1000 degrees C and compositions near 30 at.% Al. (c) The equilibrium eutectoid gamma(0) --> beta + gamma(1) and peritectoid gamma(0) + epsilon(1) --> gamma(1) reactions do not occur in this system. (C) 1998 Elsevier Science S.A.