Interface Segregation in α⁄β Brass

Abstract

Interface segregation behavior in α(fcc)⁄β(bcc) brass two-phase bicrystals and polycrystals was investigated by means of EPMA. The following facts were made clear from the results of this work.
(1) Segregation profile in polycrystals was recognized as both the enrichment of Zn in β phase and the depletion of Zn in the α phase adjoining to the α⁄β interface. In two-phase bicrystals, however, the depletion of Zn in the α phase adjoining to the α⁄β interface was not observed.
(2) The width and height of these segregation in two-phase bicrystals increased with increasing annealing temperature. More pronounced segregation was observed in the bicrystals than in the polycrystals.
(3) It was explained by the crystallographic considerations that the segregation profile mentioned above was due to the character of the plane-matched interface structure. Furthermore, the interfacial energy and the lattice strain energy before and after the segregation were estimated. The energetic consideration also explained the experimental results reasonably.
(4) A lack of the depletion of Zn in α phase adjoining to the interface in two-phase bicrystals was considered to result from the higher mobility of the interface than that of Zn atoms in the α phase.