General existence of ledges on α1 plates in Cu-Zn-Al alloys.

A transmission electron microscopy (TEM) study was made of the interphase boundary structure between the matrix and α₁ plates formed at 250 °C, 300 °C, and 350 °C in three Cu-Zn-Al alloys. The experiments showed that the α₁ plates formed at each temperature studied in all of the alloys are initially free of stacking faults. This observation, confirming the results of previous investigations, shows that these plates cannot have formed by a shear mechanism. Ledges were shown to exist on the broad faces and/or at the growth edges of the α₁ plates. Indirect evidence implies that the ledges are mobile and that they can migrate along different directions on the broad faces. [ABSTRACT FROM AUTHOR]