Synchrotron white Laue nanodiffraction study on the allotropic phase transformation between hexagonal and monoclinic Cu6Sn5

Abstract

The allotropic phase transformation of Cu6Sn5 from a hexagonal (η) to monoclinic (η′) structure at 186 °C is scientifically interesting and technologically important. As the η′ lattice is crystallographically pseudosymmetrical with η, the identifications of η and η′ and their transformation are extremely difficult via traditional techniques, such as electron backscatter diffraction, transmission electron microscopy, or, X-ray powder diffraction. Herein, a study of the η-to-η′ transformation and phase distribution by Laue diffraction via synchrotron white X-ray radiation with a 70 nm × 70 nm focused beam is conducted. The allotropic species (η and η’) can be well distinguished, and two-stage phase transformation kinetics is proposed.

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