Experimental Description of the Al-Cu Binary Phase Diagram

摘要

The phase diagram of the Al-Cu binary system was reinvestigated experimentally. The current study was designed to contribute to a better description of those parts of the phase diagram which are disputed in the current scientific literature, and in addition, to study the phase equilibria at 300 degrees C. The melting behavior of the -phase was confirmed to be peritectic. A metastable congruent solidification of the -phase was observed from the microstructural examination of as-cast samples. The location of the liquidus curve in this region of the phase diagram was more accurately defined using DSC measurements taken at slow-heating rates (1 degrees C min(-1)). The temperature stability of the -phase was reevaluated and was found to lie in the range 373-597 degrees C. The phase boundaries of the + epsilon two-phase field were experimentally defined. Difficulties in defining the / transition were addressed by a combined EDX/XRD investigation of more than ten samples that had been annealed in the temperature range of 500 to 750 degrees C. The ( + ) two-phase field was postulated from XRD studies of quenched samples. The temperature of the ordering reaction within the () + phase field was experimentally determined to be 779.6 degrees C. All other parts of the Al-Cu phase diagram studied here were found to be in very good agreement with the most recent previous descriptions.