THE STRUCTURE OF METASTABLE (111)(ALPHA) PRECIPITATES IN AN AL-2-CENTER-DOT-5 WT-PERCENT CU-1-CENTER-DOT-5 WT-PERCENT MG-0-CENTER-DOT-5 WT-PERCENT AG ALLOY
Hd. Chopra et al., THE STRUCTURE OF METASTABLE (111)(ALPHA) PRECIPITATES IN AN AL-2-CENTER-DOT-5 WT-PERCENT CU-1-CENTER-DOT-5 WT-PERCENT MG-0-CENTER-DOT-5 WT-PERCENT AG ALLOY, Philosophical magazine letters, 71(6), 1995, pp. 319-324
Electron microdiffraction experiments have been used to study a fine m
etastable precipitate (designated X) that forms as platelets on the {1
11}(alpha) planes of the alloy Al-2.5 wt% Cu-1.5 wt% Mg-0.5 wt% Ag, ag
ed at 513 K. Microdiffraction patterns observed from individual platel
ets indicated that they have a hexagonal structure with the unit-cell
parameters a = 0.496 nm and c = 1.375 nm, and an orientation relations
hip of (0001)(X)\\(111)(alpha) and [<10(1)over bar 0>](X)\\[1(1) over
bar0$](alpha). Although earlier work by Bergman, Waugh and Pauling on
similar alloys suggested that the platelets had a b.c.c. T-phase struc
ture, the present results indicate that X phase is not in fact an isom
orph of the T-phase that has been observed in the ternary Al-Zn-Mg and
Al-Cu-Mg alloy systems.