Related Experiment Video
Updated: Oct 2, 2026

Determining the Mechanical Strength of Ultra-Fine-Grained Metals
Published on: November 22, 2021
Shear instability of gamma-Fe in bulk and in ultrathin films
1Institut für Materialphysik and Center for Computational Materials Science, Universität Wien, Sensengasse 8/12, A-1090 Wien, Austria.
Abstract:
Using ab initio local-spin-density calculations we demonstrate that along the Bain path describing the transformation of face-centered-cubic (fcc) gamma-Fe into body-centered-cubic (bcc) alpha-Fe, tetragonal Fe is unstable against monoclinic shear deformations producing a nearly bcc structure. In the limit of a monolayer adsorbed on a fcc substrate, the epitaxial constraint suppresses the shear instability, but in ultrathin films with three to six monolayers a striped pattern of near-bcc domains develops, confirming recent observations by scanning tunneling microscopy. A strong correlation between the shear instability and the magnetic state is reported.
Related Concept Videos
Elastic Strain Energy for Shearing Stresses
Shearing Strain
Shearing Stress
The average shearing stress can be calculated by dividing the shear by the area of the cross-section.
Problem Solving on Stress and Strain
Shearing Stresses in a Beam: Problem Solving
Shear on the Horizontal Face of a Beam Element

