Strain-induced suppression of the miscibility gap in nanostructured Mg₂Si–Mg₂Sn solid solutions

Abstract

Strain-induced suppression of the miscibility gap in solid solutions of Mg2Si and Mg2Sn was studied to reduce lattice thermal conductivity.

Uncertainty propagation in a multiscale CALPHAD-reinforced elastochemical phase-field model

“…Recently, the present authors and collaborators investigated the effect of non-equilibrium processing on the microstructure evolution (and transport properties) in the Mg 2 Si 0.7 Sn 0.3 system and found that instead of phase-separating, the system tended to form a solidsolution with superior TE performance, contrary to expectations and prior works [56,65]. This was ascribed to (elastic) coherency effects and was verified via quantitative multi-physics phase field simulations [39].…”

“…Many of these approaches have been inspired by metallurgy and thus the time is ripe to translate much of what has been learned on ICME-enabling microstructure-sensitive (structural) alloy design to the problem of designing (self-assembled) TE microstructures for optimal performance. While the modeling framework via PFM has shown to result in (semi-)quantitative predictions that compare well with experiments [39], a robust ICME research program on microstructure design of TE materials requires reliable and efficient UQ/UP frameworks. Figure 2 illustrates an schematic phase diagram in which the material shows an inherent instability in certain regions of the composition space.…”

“…Similarly, Mg 2 X{Sn,Si} system has a miscibility where the uncertainties in the Sn-rich and Si-rich boundaries (Refer to Fig. 3 of [39]) has been the center of discussions in several articles [38,39,62,63,70]. As a consequence, these uncertainties impact the chemical free energy and (the predicted) microstructure of this system.…”

“…As mentioned above, the motivating example is the propagation of uncertainty in microstructure evolution simulations in nanostructured composite thermoelectrics (TE) [42][43][44][45] via direct coupling of CALPHAD thermodynamic assessments [46] with multi-physics phase field models (PFM) [28,39] that account for both chemical and elastic driving forces for structure formation. The example is motivated by recent work by some of the present authors [39] on the dramatic effect that processing has on the microstructure (and TE performance) in Mg 2 Si-Mg 2 Sn alloys, but has a much broader applicability as CALPHAD/PFM-based microstructure simulations are pervasive in ICME-based frameworks for microstructure-sensitive materials design [47][48][49][50][51], and properly accounting for uncertainty is necessary to make design choices with proper confidence bounds.…”

“…including the exploitation of spontaneous self-assembly or nonequilibrium processing of nanostructures to enhance phononscattering [39,42].…”