Change in preferential orientation of α phase transforming from β′ Cu-Zn alloys with zinc concentration

In order to clarify the effect of Zn concentration on the habit planes of a phase in the β′' matrix, an embossing method and SEM-ECP observation were applied to Cu-39.6 mass%Zn alloy and Cu-43.2 mass%Zn alloy. In the both alloys, α phase, which always exists as a pair of plates, had a straight line at the center of the triangular α phase as one of the feature. For the relatively lower Zn content alloy (Cu-39.6 mass%Zn alloy), the habit plane of α phase in β′ matrix was found near {3 17 18} _m plane of the matrix. In this case, four kinds of crystallographically equivalent habit planes, (3 17 18), (3 18 17), (3 17 18) and (3 18 17) existed, and the values of these habit planes were almost equal to those of {5 27 29} _m obtained for Cu -41.7 mass%Zn alloy. For the relatively higher Zn content alloy (Cu-43.2 mass%Zn alloy), the habit plane of α phase inβ′ matrix existed near {3 14 14} _m plane of the matrix. Merely two kinds of crystallografically equivalent habit planes, (3 14 14) and (3 14 14) were found in this alloy.