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Anisotropy; Aspect ratio; Binary alloys; Copper alloys; Inverse problems; Lithium alloys; Precipitation (chemical), Anisotropic stress field; Chemo-mechanical couplings; Composition dependence; Elastic anisotropy; Interfacial mobility; Interfacial property; Multi-phase field simulations; Precipitation process, Aluminum alloys
Abstract:
The effects of anisotropic interfacial properties and heterogeneous elasticity on the growth and ripening of plate-like θ’-phase (Al2Cu) in Al-1.69 at. Cu alloy are studied. Multi-phase-field simulations are conducted and discussed in comparison with aging experiments. The precipi-tate/matrix interface is considered to be anisotropic in terms of its energy and mobility. We find that the additional incorporation of an anisotropic interfacial mobility in conjunction with the elastic anisotropy result in substantially larger aspect ratios of the precipitates closer to the experimental observations. The anisotropy of the interfacial energy shows comparably small effect on the precip-itate’s aspect ratio but changes the interface’s shape at the rim. The effect of the chemo-mechanical coupling, i.e., the composition dependence of the elastic constants, is studied as well. We show that the inverse ripening phenomenon, recently evidenced for δ’ precipitates in Al-Li alloys (Park et al. Sci. Rep. 2019, 9, 3981), does not establish for the θ’ precipitates. This is because of the anisotropic stress fields built around the θ’ precipitates, stemming from the precipitate’s shape and the interaction among different variants of the θ’ precipitate, that disturb the chemo-mechanical effects. These results show that the chemo-mechanical effects on the precipitation ripening strongly depend on the degree of sphericity and elastic isotropy of the precipitate and matrix phases. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
