Formation and growth of cu3auii in a deformed matrix

Abstract Copper-gold alloys containing 30 at.% gold were converted into powder, by filing at room temperature and at 77K, and into plates by rolling at room temperature (reduction in area 90%). The ordering was studied by means of X-ray diffraction techniques. The powder samples in the as-deformed or recrystallized condition were annealed at different temperatures and iced-brine quenched. In filings, prepared at room temperature, the satellites and the central superstructure reflection grew at about the same rate, implying the direct formation of Cu 3 Au II from the SRO-state and not via the Cu 3 Au I-I phase. The degree of order was lower in the cold-worked samples, whereas the Cu 3 Au II -content appears to be little affected by cold-work. Of the plates, annealed for various times at 361°C, the microhardness vs time curve displays two maxima, the texture parameter T 220 , i.e. the ratio of peak intensities, varies in phase with the 111 microhardness curve and recrystallization occurs immediately beyond each maximum. In between the two maxima, the original texture of the cold-worked sample reappears and from the second maximum on a cube texture develops. Cu 3 Au II is definitely present in a cold-worked plate after 32 hr annealing, whereas in an initially recrystallized plate, this phase is already clearly visible after 8 hr annealing.