Feathery structure discovered in the reaction zone of diffusion couple Zn/CuTi2

A new morphology named as feathery structure was firstly discovered in the reaction zone of system Zn/CuTi2 annealed at 663 K for various times. Using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), it was clarified that the rachis of the feathery structure contains the aggregated phases of TiZn3 and CuZn2, while the barb is really the periodic-layered structure of the two phases. The formation mechanism was ascribed to the serrated co-growth of the periodic-layered structure and the aggregate structure at the reaction front corresponding to the different crystal orientations of substrate CuTi2. Very importantly, the discovery of the feathery structure provided a clear and comprehensive pattern for understanding the morphology evolution of the ternary systems from the simple-layered structure to the complicated feathery structure.

Based on the analysis of the bond-breaking energies of Cu and Ti of substrate CuTi2, it can be imagined that, for example, when the polished reaction plane of CuTi2 is located between the two planes (010) and (013), the feathery structure then could be formed as the co-growth result of the periodic-layered structure on the (013) plane and the aggregate structure on the (010) plane, respectively. As an important experimental evidence, the regular serrated interface could be observed clearly at the reaction front during the formation of the feathery structure.Figure optionsDownload as PowerPoint slideHighlights
► This paper reports the discovery of a new product morphology named as feathery structure.
► The discovery is important to the fundamental research of solid-state reaction and diffusion.
► The mechanism is clarified based on the analysis of the bond breaking energies of Cu and Ti.