High-pressure mechanochemistry: Conceptual multiscale theory and interpretation of experiments

Valery I. Levitas
Phys. Rev. B 70, 184118 – Published 19 November 2004

Abstract

Fifteen mechanochemical phenomena observed under compression and plastic shear of materials in a rotational diamond anvil cell (RDAC) are systematized. They are related to strain-induced structural changes (SCs) under high pressure, including phase transformations (PTs) and chemical reactions. A simple, three-scale continuum thermodynamic theory and closed-form solutions are developed which explain these phenomena. At the nanoscale, a model for strain-induced nucleation at the tip of a dislocation pile-up is suggested and studied. At the microscale, a simple strain-controlled kinetic equation for the strain-induced SCs is thermodynamically derived. A macroscale model for plastic flow and strain-induced SCs in RDAC is developed. These models explain why and how the superposition of plastic shear on high pressure leads to (a) a significant (by a factor of 3–5) reduction of the SC pressure, (b) reduction (up to zero) of pressure hysteresis, (c) the appearance of new phases, especially strong phases, which were not obtained without shear, (d) strain-controlled (rather than time-controlled) kinetics, or (e) the acceleration of kinetics without changes in the PT pressure. Also, an explanation was obtained as to why a nonreacting matrix with a yield stress higher (lower) than that for reagents significantly accelerates (slows down) the reactions. Some methods of characterization and controlling the SCs are suggested and the unique potential of plastic straining to produce high-strength metastable phases is predicted.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
9 More
  • Received 30 May 2003

DOI:https://doi.org/10.1103/PhysRevB.70.184118

©2004 American Physical Society

Authors & Affiliations

Valery I. Levitas*

  • Texas Tech University, Center for Mechanochemistry and Synthesis of New Materials, Department of Mechanical Engineering, Lubbock, Texas 79409-1021, USA

  • *Email address: valery.levitas@coe.ttu.edu; Fax: (253) 679 8926.

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 70, Iss. 18 — 1 November 2004

Reuse & Permissions
Access Options

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×