The α ↔ γ transformation in Fe and Fe–Au thin films, micro- and nanoparticles – an in situ study
Source abstract
Abstract
Abstract We studied the α ↔ γ phase transformation in Fe and Fe–Au thin films and nanoparticles employing in situ X-ray diffraction by varying the temperature (from room temperature up to 1100 °C), film thickness, particle size and composition. In pure Fe particles the transformation did not occur, whereas in the respective thin films a “ reverse size effect ” was observed – only the thinnest and the thickest films underwent the transformation. In contrast, the γ-Fe phase was observed in all Fe–Au samples (bi-particles and thin films), and remained metastable at room temperature. γ-Fe particles as large as 300 nm were observed by electron microscopy. The results are discussed in terms of the difference in available nucleation sites in the particles, bi-particles and films; critical nucleus size and nucleation energy barrier; and the facilitating presence of Fe/Au interfaces. The reverse size effect challenges the paradigm that phase stability at the nanoscale changes monotonously with a decrease of the system’s characteristic dimensions.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: nanoparticles nucleation surface interactions · Microstructure and mechanical properties · Aluminum Alloy Microstructure Properties
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