Abstract
We present a multi-scale phase field modeling of stationary microstructures produced under 1 MeV krypton ion irradiation in a phase separating concentrated solid solution of silver and copper. We show that the mixture reaches ultimately a stationary micro-structural state made of phase domains with composition and size distribution mapped to the values of the incident flux of particles and of the temperature, variables that help defining a non equilibrium phase-diagram for the irradiated alloy. The modeling predicts the formation of diverse microstructures likely connected to spinodal hardening, thus opening the perspective of the on-purpose tuning of mechanically resistant microstructures and the preparation of metastable alloys with mechanical properties improved by comparison to counterparts obtained via classical thermo-mechanical treatments.
Highlights
Patterned microstructures forming in driven materials have been for long a hot subject of applicative research since it is foreseen that thereby new preparation routes can emerge for industrial materials with desired physical properties, surpassing these obtained via classical preparation routes[1,2]
Little is known about the mechanical strength of the irradiated alloy and the variety of microstructures resulting from changes in the experimental parameters such as, the nominal composition, the temperature, the flux and the energy of incident ions, this knowledge is the prerequisite for effectively operating microstructural engineering[31]
The present work shows that at any value of the nominal composition of a binary alloy, stationary irradiation microstructures are precisely located within a pseudo-phase diagram spanned by the temperature and the irradiation flux, which knowledge allows for identifying the regions triggering spinodal hardening, while enabling the flexible tailoring of microstructural features connected with the macroscopic mechanical behavior
Summary
By comparison to the case above, diameter distributions are enlarged, asymmetric, and heavily tailed, indicating that the relative proportion of large precipitates increases on increasing the temperature (Figs 3 and 4, right column) Considered all together, these results suggest that, under ion irradiation, composition modulations amplifying to form stationary microstructures extend over a pretty narrow range of wavelengths in difference with radiation-induced dissolution of precipitates during annealing, where coarsening is disrupted above a critical size value[51,52]. It must be emphasized here on that only the contribution of the spinodal decomposition to the strength has been considered and that other causes may further harden the alloy as would expectedly happen when the dislocation density increases in response to a flux increase This adds to the possible failure at high temperatures of the CRSS prediction via equation 3 since the concentration profile is not sinusoidal in shape anymore as is shown in the present work. Further effort is required for satisfactorily modeling the evolution of the CRSS under irradiation and for clarifying the origins of hardening regimes observed in irradiated alloys
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