Nontrivial nanostructure, stress relaxation mechanisms, and crystallography for pressure-induced Si-I → Si-II phase transformation
Abstract
Crystallographic theory based on energy minimization suggests austenite-twinned martensite interfaces with specific orientation, which are confirmed experimentally for various materials. Pressure-induced phase transformation (PT) from semiconducting Si-I to metallic Si-II, due to very large and anisotropic transformation strain, may challenge this theory. Here, unexpected nanostructure evolution during Si-I → Si-II PT is revealed by combining molecular dynamics (MD), crystallographic theory, generalized for strained crystals, and in situ real-time Laue X-ray diffraction (XRD). Twinned Si-II, consisting of two martensitic variants, and unexpected nanobands, consisting of alternating strongly deformed and rotated residual Si-I and third variant of Si-II, form$$\{111\}$${111}interface with Si-I and produce almost self-accommodated nanostructure despite the large transformation volumetric strain of$$-0.237$$−0.237. The interfacial bands arrest the$$\{111\}$${111}interfaces, leading to repeating nucleation-growth-arrest process and to growth by propagating$$\{110\}$${110}interface, which (as well as$$\{111\}$${111}interface) do not appear in traditional crystallographic theory.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 21, 2022
- Source ID
- 10.1038/s41467-022-28604-1
Entities
People
- Dmitry Popov
- Hao Chen
- Nenad Velisavljevic
- Valery I. Levitas
Organizations
- Iowa State University
- National Science Foundation
- Office of Naval Research