In-situ study of rules of nanostructure evolution, severe plastic deformations, and friction under high pressure

TL;DR

This study presents the first in-situ analysis of nanostructure evolution, yield strength, and friction during severe plastic deformation under high pressure, revealing steady-state behaviors and challenges in plasticity theory.

Contribution

It introduces a novel in-situ experimental approach using rough diamond anvils to study nanostructure evolution under high pressure, providing new insights into steady-state parameters and plasticity.

Findings

{}-Zr reaches steady states independent of pressure and strain.

Steady states for -Zr and -Zr differ with different anvil types.

In-situ measurements reveal pressure-dependent yield strength evolution.

Abstract

Severe plastic deformations under high pressure are used to produce nanostructured materials but were studied ex-situ. We introduce rough diamond anvils to reach maximum friction equal to yield strength in shear and perform the first in-situ study of the evolution of the pressure-dependent yield strength and nanostructural parameters for severely pre-deformed Zr. {\omega}-Zr behaves like perfectly plastic, isotropic, and strain-path-independent. This is related to reaching steady values of the crystallite size and dislocation density, which are pressure-, strain- and strain-path-independent. However, steady states for {\alpha}-Zr obtained with smooth and rough anvils are different, which causes major challenge in plasticity theory.