日本金属学会誌

J. Japan Inst. Metals, Vol. 40, No. 11 (1976),
pp. 1117-1122

Effect of the Moving Direction of the Interface on Morphological Stability of α/β Phase Interfaces in the Cu-Zn System

Isao Itoh1

1Faculty of Engineering, Gumma University, Kiryu

Abstract:

An experimental investigation into the morphological stability of α/β phase interfaces in the Cu-Zn system at 700°C was undertaken. Using two-phase infinite diffusion couples, all with the same α terminal composition but with various β terminal compositions, the transition from a planar to a nonplanar α/β interface was indexed. The transition corresponded to the reversion of the direction in which the interface moved. The nonplanar interfaces were formed in the diffusion couples with initial zinc contents of β -brasses lower than that of about 44.5 wt%Zn and the interfaces moved in the direction of β -phase.
It is well known fact that ignoring the effects of preferential grain boundary diffusion and anisotropic crystal growth, it is impossible for a binary isothermal diffusion couple to sustain a nonplanar interface. The experimental results showed that the formation of the nonplanar α/β interface in the Cu-Zn system originated in the preferential growth of needle-like α -phase crystal in the < 111 > direction into a matrix of β -phase. Such occurrence of the preferential growth was supposed to be associated with the special characteristic of β -phase crystal which had a large elastic anisotoropy.


(Received 1975/12/9)

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