Thermally promoted evolution of open-volume defects and Cu precipitates in the deformed FeCu alloys

Precipitation of supersaturated solute in H ion irradiated Fe-Au and Fe-Au-W alloys studied by positron annihilation spectroscopy

“…The trapping behavior of positron at precipitate is a common feature, because positron will always be captured by near defects, like vacancy, dislocation. Moreover, positrons are trapped by different embedded particles, like Cu clusters/precipitates [34] or Au precipitates [35]. The S parameter represents the fraction of positron annihilations as a result of the interaction with low-momentum electrons and increases for an increasing fraction of open volume defects.…”

“…The increase of S parameter was attributed to the misfit between the precipitates and the matrix, and the peak disappeared due to the growth of precipitates which decreased the S parameters and increased the W parameters [35]. During the initial aging step of 0.5 h, the H-V complexes begin to decompose to form new vacancies, leading to an increase in the S parameter, while the solute Au atoms occupy the vacancies, causing a reduction in the S parameter [34,38]. The new vacancies formed by decomposition of the H n V m clusters will lead to the increase of S parameter, and also the new vacancies partly occupied by thermally activated Au atoms and recovered duo to annealing will cause the decrease of S parameter.…”