|About this Abstract
||MS&T21: Materials Science & Technology
||Nucleation of Solid-State Phase Transformations
||Critical Nuclei at Hetero-phase Interfaces
||Rongpei Shi, Tae Wook Heo, Brandon Wood, Yunzhi Wang
|On-Site Speaker (Planned)
Two-step nucleation, wherein a metastable phase acts as a precursor for nucleating a thermodynamically stable phase, has been widely observed in many solid-state reactions. Among the advantages of two-step nucleation is that the stable phase may nucleate heterogeneously at the hetero-phase interface between the original and the precursory phases. Nevertheless, our understanding of HN at these interfaces remains incomplete. This deficiency stems from the discontinuity of the chemical potential across the hetero-phase interface, which profoundly affects the fundamental properties of the nucleus in a way that is not properly captured in existing models. Herein, we incorporate these effects to extend the classical nucleation theory to HN at hetero-phase interfaces and demonstrate that the nucleus shape along the minimum energy path is strongly size-dependent, and this additional degree- -of-freedom can result in the reduction of the critical nucleus volume and associated nucleation barrier by orders of magnitude relative to conventional predictions.