Morphology of α Phase Transforming from β′ Phase in Cu-41.7% Zn Alloys by Lower Temperature Annealing

The accurate orientation of β′ matrix was determined first by SEM-ECP, and then α phase which transformed from the β′ matrix during lower temperature annealing was observed as an embossed form by a preferential deep etching method. The embossed α phase at (011) matrix plane could be divided into two groups in shape as triangles and bend bars. The center line of the triangular α phase was almost parallel to (200) band of SEM-ECP from β′ matrix, and the sharp corner, at which the centerline was connected, had an angle about 70°. At (001) matrix plane, an embossed α phase also showed a triangular shape and a sharp corner of triangle, which connected with the center line, was embedded into β′ matrix. From SEM-ECP, center line of triangular α phase at (001) matrix plane was parallel to (200) band of SEM-ECP too. At (111) matrix plane, it was clear that the α phase consisted of one pair of two α plates. Such a pair of α plates were frequently combined with other pairs and then the more complex form built up. Especially, at (001) matrix plane, a pyramid like shape which consisted of four pairs of α plates was observed.