Stress-driven phase transformation and the roughening of solid-solid interfaces

TL;DR

This paper introduces a model explaining how stress induces morphological instabilities and roughening at solid-solid interfaces, specifically in porous materials under compression, leading to finger-like structures and stylolite formation.

Contribution

It presents a novel phase transformation model for interface roughening driven by stress in porous solids, linking free energy jumps to morphological instability.

Findings

Instability caused by free energy density jump across interface

Formation of finger-like structures aligned with compression

Explanation for stylolite roughening in sedimentary rocks

Abstract

The application of stress to multiphase solid-liquid systems often results in morphological instabilities. Here we propose a solid-solid phase transformation model for roughening instability in the interface between two porous materials with different porosities under normal compression stresses. This instability is triggered by a finite jump in the free energy density across the interface, and it leads to the formation of finger-like structures aligned with the principal direction of compaction. The model is proposed as an explanation for the roughening of stylolites - irregular interfaces associated with the compaction of sedimentary rocks that fluctuate about a plane perpendicular to the principal direction of compaction.