Mixing instabilities during shearing of metals

Area of Science:

• Materials Science
• Solid Mechanics
• Physics of Deformation

Background:

• Severe plastic deformation (SPD) is crucial in materials processing and tribology, causing microstructural changes like refinement and mixing.
• The dynamic mechanisms governing morphological evolution during SPD remain poorly understood due to experimental limitations.

Purpose of the Study:

• To experimentally and numerically investigate the morphological evolution of metallic multilayers subjected to severe plastic deformation.
• To elucidate the underlying physical mechanisms driving microstructural changes during ultrahigh strain shearing.

Main Methods:

• Experimental shearing of metallic multilayers up to ultrahigh strains.
• Numerical simulations treating material phases as nonlinear viscous fluids.
• Analysis of morphological changes including folding, delamination, and mixing.

Main Results:

• Mechanically stronger layers exhibit distinct behaviors: quasi-regular folding into periodic vortices or delamination into finer layers before mixing.
• Numerical simulations successfully replicate experimental observations, validating the model.
• The study identifies a common instability mechanism driving morphological evolution across different length scales, from micro- to geological.

Conclusions:

• A comprehensive strategy combining experiments and simulations reveals the dynamics of morphological evolution during severe plastic deformation.
• The findings highlight the role of interfacial instabilities in dictating microstructural outcomes in deforming solids.
• The research bridges the understanding of deformation mechanisms in materials science and geophysics.